Neurexan by Heel, Inc. (formerly known as BHI)

LIKELY EFFECTIVE

• Mental alertness. Consumption of caffeinated coffee attenuates changes in alertness and cognitive capacity that occur throughout the day. It also improves mental performance and alertness following sleep deprivation. Details: Consumption of coffee and other caffeinated beverages seems to prevent a decline in alertness and cognitive capacity when consumed throughout the day (4221,4224). Caffeine can improve mental performance and alertness following prolonged sleep deprivation (10205). With respect to mental alertness while driving, some research shows that drinking a single cup of coffee containing 80 mg caffeine in 180 mL during a 15-minute rest after simulated driving for 2 hours reduces the amount of weaving and increases speed consistency in the 3rd and 4th hours of driving when compared with drinking decaffeinated coffee. Overall, the mental effort needed to drive, driving quality, and feelings of sleepiness appear to improve with caffeine consumption (93875).

POSSIBLY EFFECTIVE

• Diabetes. Population research has found that consumption of caffeinated coffee is associated with a reduced risk of developing type 2 diabetes. Consumption of coffee also seems to be associated with a reduced risk of mortality in patients with type 2 diabetes. Details: Population research suggests that consumption of caffeinated coffee is associated with a dose-dependent reduced risk of developing type 2 diabetes (11353,11731,14313,38174,91040,91055,111040). Some research suggests that increasing coffee consumption by 1 cup daily is associated with a 6% to 9% reduction in the incidence of type 2 diabetes (91040,91055). In North American adults, consuming 6 or more cups of coffee daily is associated with a 29% lower risk of developing diabetes in females and a 54% lower risk in males (11353). Research in European adults suggests that drinking 5-6 cups of coffee daily appears to reduce diabetes risk by 61% in females and 30% in males. Drinking 10 or more cups daily reduces diabetes risk by 79% in females and 55% in males (11731). Additional research suggests that drinking 3-4 cups of coffee daily reduces the risk of diabetes by 23% to 42% when compared with drinking just 1 cup daily (14343,38174). An analysis of these and other cohort studies involving over 457,000 patients suggests that drinking 3-4 cups of coffee or decaffeinated coffee daily is associated with a 25% to 35% reduced risk of type 2 diabetes when compared with drinking 2 cups or less daily. Each additional cup of coffee consumed each day is associated with a 5% to 10% reduction in the incidence of type 2 diabetes (97368). Some population research in patients with previous gestational diabetes has also investigated the association between consumption of coffee and risk of developing type 2 diabetes. Research suggests that consumption of at least 4 cups of caffeinated coffee daily is associated with a 54% reduced risk of type 2 diabetes when compared with drinking no coffee. There is no association between consumption of decaffeinated coffee and type 2 diabetes risk (111040). Coffee consumption has also been evaluated in patients with type 2 diabetes, with mixed findings. Most population research suggests that coffee consumption is associated with a reduced risk of mortality in patients with type 2 diabetes. In one meta-analysis of observational studies, drinking high amounts of coffee was associated with a 24% reduction in mortality risk, with a 9% reduction for each additional cup of coffee (104595). In another meta-analysis, drinking up to 4 cups of coffee daily was associated with a 19% reduction in all-cause mortality and a 34% reduction in coronary heart disease (CHD) mortality when compared with not drinking coffee. Reductions in cardiovascular disease (CVD) mortality were only significant when one large study was excluded during sensitivity analyses (107836). Results of individual studies are conflicting (37805,97374,104589,104594). Additionally, a cross-sectional study in older adults with type 2 diabetes has examined the relationship between coffee consumption and CVD risk factors. This study suggests that higher coffee consumption is associated with lower fasting plasma glucose and diastolic blood pressure and higher high-density lipoprotein (HDL) cholesterol and triglyceride levels (107825). Population research has examined the relationship between coffee consumption and change in kidney function in patients with type 2 diabetes. One study in patients with normal kidney function suggests that drinking any coffee is associated with up to a 25% prevention in kidney function decline when compared with no coffee consumption. Kidney function decline was based on estimated glomerular function rate (eGFR) measurements (111043).
• Heart failure. Consumption of caffeinated coffee seems to reduce the long-term risk of heart failure in those without cardiovascular disease (CVD) at baseline. Details: A meta-analysis of three large population studies, the Framingham Heart Study (FHS), Cardiovascular Heart Study (CHS), and Atherosclerosis Risk in Communities (ARIC) study, has found that increased daily coffee consumption is associated with a reduced long-term risk of heart failure in individuals without CVD at baseline. Drinking at least 2 cups of coffee daily is associated with a 29% to 31% reduced risk of heart failure. In the analysis, total caffeine intake, but not decaffeinated coffee intake, was associated with a reduced risk of heart failure (104597).
• Overall mortality. Consumption of coffee seems to reduce all-cause mortality. The effects of coffee on specific causes of mortality are variable. Details: Population research conducted in almost 4 million international individuals suggests that long-term, daily consumption of coffee is associated with an 8% to 28% reduction in all-cause mortality when compared to low or no coffee consumption (97373,97374,103997,103998,104594,104595,105308,105311,105314,107826)(107833,107839,111033), though not all research agrees (107822). The strongest association is seen for individuals consuming 2-4 cups of coffee daily and in never smokers. Most research suggests that consuming ground, instant, or decaffeinated coffee is associated with similar reductions in mortality (97373,97374,103997,103998,104594,104595,105308,105311,105314,107833)(111033). The use of sweeteners might affect the association of coffee consumption with all-cause mortality. Population research suggests that consumption of unsweetened coffee, in amounts ranging from any to up to 4.5 cups daily depending on type of coffee, is associated with a reduction in mortality of 14% to 39% when compared with no coffee consumption. Consumption of 1.5 to 3.5 cups of sugar-sweetened coffee is associated with a reduction in mortality of approximately 30%; however, this association does not occur with higher coffee intakes or the consumption of decaffeinated coffee. Any association between the consumption of artificially sweetened coffee and mortality is unclear. When subgroup analyses were conducted to determine the association of coffee consumption with cause-specific mortality, coffee consumption was associated with a reduction in cardiovascular mortality. In some analyses, this association is for ground or decaffeinated, but not sweetened, instant, or unfiltered, coffee (97373,97374,103997,103998,104594,104595,105308,105311,105314,107833)(111032). In another analysis, consumption of coffee was inversely associated with deaths from chronic respiratory diseases, diabetes, pneumonia and influenza, and intentional self-harm. There were no associations between coffee consumption and deaths from accidents, Alzheimer disease, or kidney disease (105311). The association between coffee consumption and cancer-related mortality is less clear. Although one large meta-analysis of population research suggests that consumption of approximately 2 cups of coffee daily is associated with a 4% decrease in cancer-related mortality, the results of individual studies are mixed. One large population cohort suggests that ground or instant caffeinated coffee consumption is associated with up to a 27% reduction in cancer mortality (97374), while other analyses show no association (97373,103994,105308,105311,107822). The reasons for this discrepancy are not clear but may be related to smoking status or use of sweeteners. In one meta-analysis, consumption of each additional cup of coffee daily is associated with a 2% decrease in cancer-related mortality in non-smokers, as opposed to an increased risk in smokers (105308). Other population research suggests that only intake of unsweetened coffee, and not sugar-or artificially-sweetened coffee, is associated with a reduced risk of cancer-related mortality (111032).
• Parkinson disease. Consumption of coffee seems to reduce the risk of developing Parkinson disease. This effect seems to be dose related in males, but not in females. Details: There is evidence that the risk of Parkinson disease is lower in people who consume caffeinated beverages such as coffee, tea, and cola. For males, the effect seems to be dose related. Males consuming the greatest amount of caffeinated coffee, 28 ounces (three to four cups) or a total of 421-2716 mg of caffeine from any source daily, seem to have the greatest reduction in risk. However, a significant reduction in risk exists even with consumption of as little as approximately 1-2 cups of coffee, or 124-208 mg of caffeine, daily (6022). In females, the effect does not seem to be dose related. Moderate consumption of caffeinated coffee, 1-3 cups daily, provides the greatest reduction in risk (1238). Coffee does not appear to provide additional protection from Parkinson disease in cigarette smokers (9236).
• Postoperative ileus. Consumption of coffee seems to decrease the time to first stool and first flatus, and possibly time to discharge, after gynecological or colorectal surgeries. Details: Meta-analyses of mainly small clinical trials in patients who have undergone gynecological or colorectal surgeries show that drinking coffee decreases the time to the first stool and time to tolerating solid food by about 10-15 hours when compared with no treatment or drinking water or tea (103991,111035,112732). Although one meta-analysis found that drinking coffee does not reduce the length of hospital stay (103991), other research shows that hospital stay is reduced by up to 1.5 days; however, the validity of these results are limited by high heterogeneity. In addition, sub-analyses suggest that benefit is limited to gynecological surgery and not colorectal surgery or caesarian section (97386,111035,112732). Sub-analyses also suggest that drinking coffee does not improve bowel function after caesarian section (103991,111035). Caffeinated coffee has been most commonly consumed as 100 mL three times daily starting after surgery and until the first stool. Some studies have used decaffeinated coffee (93876,97386,103991,111035,111039).

POSSIBLY INEFFECTIVE

• Esophageal cancer. Consumption of coffee does not seem to be associated with a reduced risk of esophageal cancer. Details: Population research has found that coffee intake is not associated with the incidence of esophageal cancer (9222,90186,100874). However, subgroup analyses have found coffee consumption may be associated with a reduced risk of esophageal cancer in patients from East Asia (100874).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Attention deficit-hyperactivity disorder (ADHD). Although there has been interest in consuming coffee for ADHD, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Atherosclerosis. It is unclear if consuming coffee is beneficial for atherosclerosis. Details: Population research has found that drinking coffee is not associated with prevalent coronary-artery calcium, a subclinical marker of atherosclerosis, in patients without known coronary heart disease (97371).
• Atrial fibrillation. It is unclear if consuming coffee affects the risk of atrial fibrillation. The available research is conflicting. Details: A meta-analysis of observational research suggests that coffee intake is not associated with the incidence of atrial fibrillation (100860). However, a more recent observational study suggests that drinking at least 1 cup of coffee per week is associated with a 40% increased risk of atrial fibrillation, with the highest incidence of atrial fibrillation occurring in adults consuming at least 6 cups daily. A sub-analysis found that this association remained only for White participants and not other ethnicities (111042). This study was limited by its relatively small sample size and a higher than general proportion of smokers. Some observational research in elderly persons following the Mediterranean diet suggests that consuming 4-28 cups of coffee monthly (up to 1 cup daily) is associated with a lower risk of atrial fibrillation when compared with 3 cups or less monthly. Consuming more than 1 cup of coffee daily was not associated with reduced risk (103988). However, it is unclear if this association was due to moderate coffee consumption, the Mediterranean diet, or other, unidentified factors.
• Bladder cancer. Population research suggests that coffee consumption does not reduce the risk of bladder cancer. Details: Although earlier evidence has been conflicting (97375,97376), the most comprehensive analysis of cohort and case control studies has found that coffee consumption is not associated with bladder cancer risk. In subgroup analyses of females, males, or non-smokers, coffee did not affect risk (103992).
• Brain tumor. It is unclear if consuming coffee reduces the risk of brain cancer. Details: Observational research has found that consumption of coffee is associated with a lower risk of brain cancer in Asian populations, but not in American populations (100870).
• Breast cancer. Population research suggests that coffee consumption does not reduce the risk of breast cancer. Details: Population research has found that consumption of coffee is not associated with a reduced incidence of breast cancer (9235,97377,107823).
• Cancer. Although there has been interest in using rectal coffee enemas for the treatment of cancer, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Cardiovascular disease (CVD). Some population research has found that drinking coffee is associated with a reduced risk of heart failure, but not with a reduced risk of major adverse cardiac events, coronary heart disease, or CVD in general. In patients with a history of CVD, coffee consumption may reduce CVD-related mortality. However, at least some evidence suggests that there is a J-shaped association between coffee consumption and the risk of acute coronary syndromes. Details: A meta-analysis of three large population studies, the Framingham Heart Study (FHS), Cardiovascular Heart Study (CHS), and Atherosclerosis Risk in Communities (ARIC) study, suggests that increased daily coffee consumption is associated with a reduced long-term risk of heart failure in individuals without CVD at baseline. Drinking at least 2 cups of coffee daily is associated with a 29% to 31% reduced risk of heart failure. However, there was no association between coffee consumption and risk of stroke, coronary heart disease, or CVD in general. In the analysis, total caffeine intake, but not decaffeinated coffee intake, was associated with a reduced risk of heart failure (104597). In one cohort study, there was no association between past coffee-drinking and the prevalence of having coronary heart disease as determined by a coronary angiography (104588). However, a large population study suggests that drinking up to 5 cups daily of instant, ground, or decaffeinated coffee is associated with a reduced risk of incident CVD, including coronary heart disease, cardiac failure, and/or ischemic stroke, of approximately 11% (111033). The association between coffee consumption and arrhythmia has also been investigated. In one population study, there was a 3% reduced risk of arrhythmia for each additional cup of habitual coffee consumed. Similar effects were seen when atrial fibrillation and supraventricular tachycardia, but not ventricular tachycardia, were independently analyzed (105310). More recent population research suggests that consuming 1-5 cups daily of ground or instant coffee, but not decaffeinated coffee, is associated with up to a 17% reduced risk of arrhythmia when compared with not consuming coffee. Intake of more than 5 cups was no longer associated with a reduced risk of arrhythmia (111033). Some population research suggests a J-shaped association between regular coffee consumption and the risk of developing acute coronary syndromes. Moderate consumption of less than 300 mL daily (about 1.3 cups) was associated with a lower risk of developing acute coronary syndromes, whereas regular consumption of 300 mL daily or more was associated with an increased risk (11318). However, other population research in people without a history of CVD suggests that drinking more than 6 cups of coffee daily does not appear to be associated with an increased risk of developing coronary heart disease (14343). The association between coffee consumption and CVD-related mortality has also been evaluated in people with CVD. Population research suggests that coffee consumption is associated with a reduction in CVD-related mortality. In some analyses, this association is for ground or decaffeinated coffee only (97373,97374,103997,103998,104594,104595,105308,105311,105314). A meta-analysis of a small number of population studies suggests that consuming coffee for at least 1 year after a myocardial infarction (MI) is associated with a small reduction in risk of CVD-related mortality and no increased risk of all-cause mortality or major cardiac events, such as a recurrent MI or stroke (104882). In patients with a history of acute coronary syndrome, including acute MI or unstable angina, consumption of 1-3 cups of coffee daily is associated with a reduced risk of overall mortality over a 4-year period, especially in never or former smokers. However, in those who are current smokers, consuming more than 3 cups daily is associated with a more than 2-fold increased risk of overall mortality (8533,105313). A large observational study which followed patients with stable coronary artery disease for 5 years also suggests that there is no association between coffee consumption and CVD-related mortality, myocardial infarction, or stroke (112735).
• Chronic kidney disease (CKD). It is unclear if consuming coffee is beneficial for the prevention or management of CKD. Details: A small meta-analysis of population research has found that coffee consumption is associated with a 14% reduced incidence of CKD; drinking at least 2 cups daily seems to have the most benefit. Coffee consumption is also associated with an 18% reduced incidence of progression to kidney failure, as well as lower odds of having albuminuria. In addition, coffee consumption is associated with a reduced risk of CKD-related death, with at least 4 cups daily providing the most benefit when compared with drinking no coffee (104586). The validity of these findings is limited by the heterogeneous definitions of CKD, kidney failure, and albuminuria in the individual studies, as well as the comparisons of coffee consumption.
• Cognitive function. It is unclear if consuming coffee is beneficial for cognitive function. Details: Some population research has found that higher lifetime coffee consumption might positively affect cognitive function among females aged 80 years or older (10620). Additionally, a small clinical study in healthy adults shows that consuming a single dose of regular coffee 220 mL containing 100 mg of caffeine improves reaction time and working memory, but not episodic memory, when compared with placebo (100864).
• Colorectal cancer. It is unclear if consuming coffee is beneficial for the prevention or treatment of colorectal cancer. Details: A meta-analysis of cohort studies conducted in North America and Europe suggests that there is no association between coffee intake and the incidence of colorectal cancer (97385). However, population research conducted in Japan and Korea suggests that drinking coffee is associated with a lower risk of colorectal cancer, with the greatest reduction seen in patients consuming 3 or more cups of coffee daily (9222,97384,107832,111041). In one study, risk reduction increased from 32% to 78% when adjusted for the use of coffee additives, including cream and sugar (107832). In addition, drinking coffee is associated with a reduced risk of disease progression and death in patients with advanced or metastatic colorectal cancer. Each additional cup daily is associated with a 5% reduced risk of cancer progression and a 7% reduced risk of death. The greatest benefits were associated with drinking at least 4 cups daily when compared with no coffee consumption (104591).
• Constipation. Although there has been interest in consuming coffee for constipation, there is insufficient reliable information about the clinical effects of coffee for this purpose.
• Dementia. It is unclear if consuming coffee is beneficial for preventing dementia. Details: One meta-analysis of observational studies including nearly 329,000 adults has found that drinking coffee is not associated with a lower risk of dementia or Alzheimer disease (100866). Conversely, other observational research has found evidence of benefit, but results are conflicting. A meta-analysis of observational studies in nearly 334,000 adults has found a reduced risk of any cognitive deficit (including mild cognitive impairment and dementia) or dementia alone in those drinking less than 2.8 or 2.3 cups of coffee daily, respectively, when compared with not drinking coffee (107829). The validity of these findings is limited by a lack of discussion of heterogeneity and variability in sensitivity analyses. An individual observational study in nearly 14,000 adults has found that coffee and caffeine consumption is associated with dose-dependent reductions in dementia risk, especially in males, and that drinking at least 3 cups of coffee daily is associated with a 50% lower risk of dementia when compared with not drinking coffee (107841). Coffee consumption has also been studied in combination with tea. An observational study has found that drinking 0.5-1 cup of coffee with at least 4 cups of tea or 2-3 cups of coffee and tea each daily is associated with a 28% to 30% reduced risk of dementia when compared with not drinking coffee and tea (107204).
• Depression. It is unclear if consuming coffee is beneficial for reducing the risk of depression. Details: Observational research has found that higher coffee consumption is associated with a 24% lower risk of depression when compared with lower coffee consumption. Drinking 400-600 mL of coffee daily is associated with 16% lower risk of depression when compared with not consuming coffee (100863).
• Endometrial cancer. It is unclear if consuming coffee is beneficial for the prevention of endometrial cancer; the available research is conflicting. Details: One meta-analysis of prospective cohort studies suggests that drinking coffee is associated with a dose-dependent reduction in the risk of endometrial cancer. Increasing coffee consumption by 4 cups daily is associated with a 20% reduction in endometrial cancer risk (97381). Another meta-analysis of population research suggests that the highest intake of caffeinated coffee, but not decaffeinated coffee, is associated with a 34% reduced risk of endometrial cancer when compared with the lowest. A sub-analysis suggests that this association is limited to individuals with a high body mass index (111036). In contrast, earlier meta-analyses and one large prospective cohort study conducted in the United Kingdom suggests that drinking coffee is not associated with a reduced risk of endometrial cancer in general; however, there may be some protection in obese females drinking at least 2 cups of caffeinated coffee daily (93873,97381,97382).
• Fractures. It is unclear if consuming coffee is beneficial for fracture prevention. Details: Multiple meta-analyses of observational research suggest that the highest intake of coffee is not associated with a difference in the odds of fracture when compared with the lowest intake. However, any association may be dependent on the dose of coffee and/or the location of research (111034,112734). A dose-response analysis in one meta-analysis suggests that consuming 0.5 to 4 cups daily, but not higher amounts, is associated with a small reduction in the incidence of hip fracture when compared with no coffee consumption. Additional sub-analyses suggest that while the highest coffee consumption was associated with a 25% reduced risk of fracture in studies conducted in Europe and North America, the opposite is true in studies conducted in Asia where the risk is increased by 37% (111034).
• Gallbladder disease. Population research suggests that consuming coffee may reduce the risk of developing symptomatic gallstone disease. Details: Population research has found that the consumption of caffeinated beverages, including coffee, that provide at least 400 mg of caffeine (two or more cups of coffee) daily is associated with a significantly reduced risk of developing symptomatic gallstone disease (3345,8032). The effect seems to be dose-dependent; consumption of 800 mg caffeine (four or more cups of coffee) daily is associated with the greatest reduction in risk (3345).
• Gastric cancer. It is unclear if consuming coffee reduces the risk of gastric cancer. Details: Overall, meta-analyses of observational research suggest that coffee consumption does not affect gastric cancer risk. However, subgroup analyses of patients living in the United States suggest that consuming coffee is associated with an increased risk of gastric cancer (100873,111038). One sub-analysis suggests that consuming 6.5 or more cups of coffee daily was associated with a 36% greater risk of gastric cancer (100873).
• Gout. It is unclear if consuming coffee is beneficial for preventing gout. Details: Epidemiological research has found that the risk of developing gout over a 12-year period is 40% lower in males aged 40-75 years who drink 4-5 cups of caffeinated coffee daily, compared with those who don't drink coffee. In people who drink 6 cups or more daily, the risk of developing gout is 59% lower. Drinking decaffeinated coffee is also associated with a reduced risk of developing gout, but the risk reduction is more modest than with caffeinated coffee (15540).
• Headache. Although caffeine is an established treatment for certain types of headache, there is insufficient reliable information about the clinical effects of coffee, specifically, for this purpose.
• Hearing loss. It is unclear if consuming coffee is beneficial for hearing loss. Details: Population research has found that consuming at least one cup of coffee daily is associated with a reduced risk of hearing impairment in males, but not females, when compared with less than one cup of coffee daily. In males, each additional cup consumed daily was associated with a 15% lower risk of hearing impairment (104592).
• Hepatitis B. It is unclear if consuming coffee is beneficial for hepatitis B. Details: Population research in patients being treated for chronic hepatitis B suggests that drinking at least 3 cups of coffee a day is associated with a reduced risk of having liver fibrosis when compared to not consuming coffee. However, this association was not present in untreated patients (111044). This study is limited by its cross-sectional design and use of blood markers, rather than the gold standard liver biopsy, for diagnosing fibrosis.
• Hyperlipidemia. It is unclear if consuming caffeinated coffee is beneficial for hyperlipidemia. Details: A meta-analysis of small, randomized, controlled trials shows that consuming caffeinated coffee for up to about 11 weeks reduces total cholesterol by 8 mg/dL, low-density lipoprotein (LDL) cholesterol by 5 mg/dL, and triglycerides by 13 mg/dL when compared with a control group. These effects appear to be dose-dependent, with the greatest reduction observed in individuals consuming 6-8 cups of coffee daily. Every additional cup of caffeinated coffee consumed daily is associated with a 3-4 mg/dL additional reduction in total and LDL cholesterol and a 6-7 mg/dL additional reduction in triglyceride levels. Decaffeinated coffee had no effect on any markers of cholesterol (97370). However, population research has found that coffee consumption is associated with slightly higher total cholesterol, LDL cholesterol, and triglyceride levels when compared with no coffee consumption (104590).
• Hypertension. Epidemiologic research suggests that consuming coffee reduces the risk of developing hypertension. Details: Some epidemiological research suggests that coffee consumption might reduce the risk of developing hypertension. A meta-analysis of epidemiologic research suggests that long-term coffee intake is associated with a modest 9% reduction in the risk of developing hypertension. However, smoking may diminish any potential benefit (97372). This analysis did not investigate the likelihood of a dose-response relationship and did not adjust for smoking status. Another epidemiologic study in a Brazilian population that did adjust for sociodemographic factors such as smoking suggests that drinking 1-3 cups of coffee daily is associated with a reduced risk of hypertension by about 18% when compared with never or almost never drinking coffee. Drinking more than 3 cups of coffee did not impact risk (103993). However, this study defined 1 cup of coffee as 50 mL; it is unclear how this intake compares with typical use in other countries. The best evidence comes from a meta-analysis of observational research which suggests that coffee intake was not associated with hypertension risk. However, coffee intake was associated with a modest reduction in hypertension risk in studies conducted in the United States (111037). In patients with hypertension, a meta-analysis of epidemiologic research suggests that habitual coffee intake is not associated with the risk of developing CVD (105312). However, other prospective population research in patients with severe hypertension, but not mild hypertension, suggests that drinking at least two cups of coffee daily is associated with a 2-fold increase in CVD mortality compared with non-coffee drinkers (111027).
• Hypotension. It is unclear if consuming caffeinated coffee is beneficial in older adults with postprandial hypotension. Details: Preliminary clinical research in older adults with postprandial hypotension shows that consuming caffeinated beverages like coffee seems to increase blood pressure (11835).
• Irritable bowel syndrome (IBS). It is unclear if consuming coffee is beneficial for preventing IBS. Details: A meta-analysis of mostly small, low-quality, observational and population research suggests that coffee consumption is associated with a modestly lower odds of developing IBS when compared with no coffee consumption. However, the validity of this result is limited by high heterogeneity (112739).
• Kidney failure. It is unclear if consuming coffee is beneficial for preventing progression to kidney failure or reducing the risk of chronic kidney disease (CKD)-related death. Details: A small meta-analysis of population research has found that coffee consumption is associated with an 18% reduced incidence of progression from CKD to kidney failure. Coffee consumption is also associated with a reduced risk of CKD-related death, with at least 4 cups daily providing the most benefit when compared with not drinking coffee (104586). This analysis is limited by the heterogeneous definitions of CKD and kidney failure in the individual studies, as well as the comparisons of coffee consumption.
• Liver cancer. It is unclear if consuming coffee reduces the risk of liver cancer. Details: A meta-analysis of observational research in approximately 2.5 million adults in Asia, North America, and Europe suggests that consuming at least 1 cup of coffee daily is associated with a 27% to 48% reduced risk of liver cancer (111016). An earlier meta-analysis of observational research suggests that regular coffee consumption is associated with a 31% lower risk of hepatocellular carcinoma when compared with no consumption. Higher coffee consumption seems to have a greater preventative effect when compared with lower coffee consumption (103989).
• Liver disease. It is unclear if consuming coffee reduces the risk of chronic liver disease. Details: Observational research has found that regular coffee consumption is associated with a 38% lower risk of chronic liver disease when compared with no consumption. Higher coffee consumption seems to have a greater preventative effect when compared with lower coffee consumption (100862).
• Lung cancer. It is unclear if consuming caffeinated coffee reduces the risk of lung cancer; the available research is conflicting. Details: Epidemiological research has found that males who consume a higher amount of dietary phytoestrogens, such as the lignan precursors found in coffee and tea, have up to a 27% lower risk of developing lung cancer when compared with those who consume smaller amounts (13190). However, conflicting evidence suggests that people who consume 2-4 or more cups of caffeinated coffee daily have a significantly increased risk of developing lung cancer (13191,90177). But drinking decaffeinated coffee seems to be associated with a decreased risk of lung cancer (13191).
• Melanoma. It is unclear if consuming coffee reduces the risk of malignant melanoma. Details: Population research has found that high coffee intake is associated with a 19% to 25% reduction in the risk of malignant melanoma when compared with low consumption. However, after adjusting for confounders, most data show no significant reduction. Drinking decaffeinated coffee is not associated with a reduced incidence of malignant melanoma (97378,97379).
• Metabolic syndrome. It unclear if consuming decaffeinated coffee is beneficial in patients with metabolic syndrome. Details: A meta-analysis of mostly small randomized controlled studies in patients with metabolic syndrome shows that consumption of decaffeinated coffee modestly reduces systolic and diastolic blood pressure when compared with control. The validity of these findings is limited by the high heterogeneity and small size of the included studies (107830).
• Nonalcoholic fatty liver disease (NAFLD). Observational research suggests that consuming coffee may reduce the risk of NAFLD. Observational and clinical research on liver fibrosis is conflicting. Details: A meta-analysis of observational research in over 50,000 patients has found that drinking 1-2 cups of coffee daily does not affect NAFLD incidence when compared with drinking less than 1 cup of coffee. However, drinking more than 3 cups of coffee daily was associated with a reduced risk of NAFLD when compared with less than 2 cups daily (103990). Other observational research has found a reduced risk of NAFLD and/or fibrosis in those who drink coffee when compared with those who do not drink coffee (100872,107831). However, the validity of these findings is limited by a relatively small population size and the lack of dose-response analyses. Two of the primary bioactive constituents of coffee, caffeine and chlorogenic acid, also have been evaluated. A small study in patients with NAFLD and type 2 diabetes shows that taking caffeine 200 mg and/or chlorogenic acid 200 mg for 6 months has no effect on the reduction of hepatic fat and fibrosis when compared with placebo (107835).
• Nonmelanoma skin cancer. It is unclear if consuming caffeinated coffee reduces the risk of nonmelanoma skin cancer. Details: Population research has found that the highest intake of coffee or caffeine is associated with an 18% reduction in nonmelanoma skin cancer risk when compared with the lowest intake. However, the benefit appears to be limited to the incidence of basal cell carcinoma. Drinking decaffeinated coffee is not associated with a reduced incidence of nonmelanoma skin cancer. The effect, if any, appears to be due to caffeine rather than coffee (97380).
• Obesity. It is unclear if consuming coffee is beneficial for weight loss in patients who are overweight or obese; the available research is conflicting. Details: Some clinical research in males who are overweight or obese and are receiving dietary counseling shows that taking coffee mannooligosaccharides 2 grams twice daily for 12 weeks reduces body weight by 6%, compared with 2.3% with placebo. The product also reduces body fat in males, but not females (93877). Additional clinical research in patients with pre-obesity shows that drinking a dark roast coffee 500 mL daily, enriched with N-methylpyridinium ions, for 4 weeks results in weight loss of 3.5%, compared with 0% with a light roast coffee enriched in chlorogenic acids. The dark roast coffee appears to reduce caloric intake (93874). However, other clinical research in adults who are overweight or obese shows that drinking caffeinated or decaffeinated coffee 885 mL daily for 8 weeks does not appear to improve glycemic control or reduce weight (93879).
• Osteoporosis. It is unclear if consuming coffee is beneficial for osteoporosis prevention. Details: A meta-analysis of observational research suggests that the highest coffee consumption is associated with a 21% reduced odds of osteoporosis when compared with the lowest (111034).
• Pancreatitis. It is unclear if consuming coffee reduces the risk of pancreatitis. Details: Observational research has found that drinking three or more cups of coffee daily is associated with a 22% lower risk of pancreatitis when compared with drinking less coffee (100871).
• Pharyngeal cancer. It is unclear if consuming coffee reduces the risk of pharyngeal cancer. Details: Observational research has found that high coffee consumption is associated with a 28% reduced odds of pharyngeal cancer when compared with low coffee consumption (100869).
• Pregnancy-induced hypertension. It is unclear if consuming coffee reduces the risk of pregnancy-induced hypertension. Details: A large prospective cohort study in pregnant patients in Japan has found that the highest total caffeine intake is associated with a 26% increased risk of pregnancy-induced hypertension when compared with no intake, but that a higher coffee intake (at least 2 cups daily) is associated with a 21% reduced risk of pregnancy-induced hypertension when compared with no intake, even when adjusted for total caffeine intake (107827). The validity of these findings may be limited by the fact that detailed information on proteinuria and hypertension were unavailable.
• Pneumonia. It is unclear if consuming coffee is beneficial for reducing the risk of pneumonia. Details: A case-control study in elderly patients has found a 50% reduced risk of pneumonia in those consuming 2 or more cups of coffee daily over the past month (107840). The validity of this finding may be limited by differences in the baseline characteristics between the matched control subjects and the cases, specifically the higher prevalence of hypertension and diabetes in the control group.
• Prostate cancer. Population research has found that coffee consumption is associated with a modestly reduced risk of prostate cancer. Details: Although some individual studies disagree (107834), population research has found that the highest coffee consumption is associated with a small reduction in the risk of prostate cancer when compared with the lowest consumption (97383,97384,104587). Sub-analyses show that coffee consumption is associated with a 7% reduced risk of localized, but not advanced or fatal, prostate cancer (97383,97384,104587).
• Stroke. It is unclear if coffee consumption, alone or in combination with tea, is beneficial for stroke, post-stroke dementia, all-cause mortality, or stroke-related mortality. The available research is conflicting. Details: Several meta-analyses of population research in patients with and without cardiovascular disease (CVD) have found no association between coffee consumption and risk of stroke (104597,104882). However, another meta-analysis of population research and an individual observational study have found that coffee consumption (e.g., 2-3 cups of coffee daily) is associated with an 8% to 12% reduced risk of stroke, especially ischemic stroke, when compared with no consumption (107204,107828). The validity of the findings from the meta-analysis is limited by the lack of a dose-response analysis. Additionally, this analysis found that consumption of 2-3 cups of coffee daily is associated with a 20% reduced risk of post-stroke dementia when compared with not drinking coffee (107204). The consumption of coffee in combination with tea has also been evaluated. An observational study has found that consumption of 2-3 cups daily each of coffee and tea, including black tea, is associated with a 32% reduced risk of stroke when compared with not drinking coffee and tea. Additionally, consumption of 0.5-1 cup of coffee and 2-3 cups of tea, including black tea, daily is associated with a 50% reduced risk of post-stroke dementia when compared with not drinking coffee and tea (107204). Coffee consumption has also been evaluated for its effects on stroke-related and all-cause mortality. One observational study has found that consumption of 1-2 cups of coffee daily is associated with a 50% reduced risk of stroke-related mortality (107822). However, another observational study in patients with a history of stroke has found no association between coffee consumption and all-cause mortality (107839).
• Thyroid cancer. It is unclear if consuming coffee reduces the risk of thyroid cancer. Details: Population research has found that high coffee consumption is associated with a 25% lower risk of thyroid cancer when compared with low consumption. Every additional cup of coffee was associated with a 5% reduction in risk (103996). More evidence is needed to rate coffee for these uses.

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LIKELY EFFECTIVE

• Coronary heart disease (CHD). A diet high in soluble fiber, such as that found in oats, reduces the risk of CHD. Details: Clinical research shows that a diet containing foods high in fiber, such as oats, oat bran, or whole oat flour, reduces the risk of CHD (2737,4960,4962,4963,4964,4965,4966,4967,4968). In 1993, the US Food and Drug Administration (FDA) approved a health claim stating that consuming at least 3 grams of soluble fiber per day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of CHD (102336). However, clinical studies show that at least 3.6 grams of soluble fiber daily is needed to reduce the risk of CHD (5786,5787,5788,5794,5795,5796).
• Dyslipidemia. A diet rich in soluble fiber, such as that found in oats, can reduce cholesterol by a moderate amount. Details: Oats, oat bran, and other soluble fibers can modestly reduce total and low-density lipoprotein (LDL) cholesterol, especially when consumed as part of a diet low in saturated fat. Consuming 56-150 grams of whole oat products such as oatmeal and oat bran, containing 3.6-10 grams of soluble fiber daily, can significantly lower total and LDL cholesterol levels. For each gram of soluble fiber consumed, total cholesterol decreases by about 1.4 mg/dL and LDL by about 1.2 mg/dL. Eating 3-10 grams of soluble fiber daily can reduce total cholesterol by about 4-14 mg/dL (4976,4977,5786,5788,5792,5794,5795,8521,107749,113488,113495). For example, eating 3 bowls of oatmeal (28 gram servings) daily, providing a total of 3 grams of soluble fiber daily, can decrease total cholesterol by about 5 mg/dL (5788). However, consuming more than 10 grams of soluble fiber daily doesn't seem to increase effectiveness (5788). A meta-analysis comparing the effects of oats and isolated beta-glucans shows that both products similarly impact lipid profiles, suggesting that the bioactive component of oats are beta-glucans (113488). Oat bran products, such as oat bran muffins and oat bran flakes, may vary in their ability to lower cholesterol, depending on the total soluble fiber content and other dietary variables (6188). Whole oat products might be more effective for lowering LDL and total cholesterol than foods containing oat bran plus soluble fiber (10145). Although oats are shown to lower total and LDL cholesterol, a meta-analysis and a small clinical study in adults with and without dyslipidemia shows that consuming oatmeal or oat products does not reduce triglycerides or increase high-density lipoprotein (HDL) cholesterol when compared with controls (113488,113495).

POSSIBLY EFFECTIVE

• Diabetes. A diet rich in whole grains, such as oats, may help prevent diabetes or improve blood glucose control in patients with type 1, type 2, or gestational diabetes. Details: Population research shows that for every 16 gram daily serving of whole grains, including oats, there is a 7% to 11% lower risk of developing type 2 diabetes (100622). There is also evidence that consuming oats can decrease blood glucose and insulin levels, as well as lipid levels, in patients with diabetes. The glycemic effects of oats depend on the level of processing of the oat products. Consuming intact oat kernels or thick-cut oats (>0.6 mm) reduces postprandial blood glucose and insulin, but consuming thin-cut, or "quick", oats has no effect (105536). Clinical research shows that consuming oats and oat bran for 4-8 weeks decreases pre-prandial blood glucose, 24-hour plasma glucose, glycated hemoglobin (HbA1c), insulin levels, and low-density lipoprotein (LDL) cholesterol in people with type 2 diabetes (4980,4982,6266,103345). Various doses have been used, including 3 grams of soluble fiber daily, or bread providing 34 grams of total fiber daily (9 grams of soluble fiber) (4961,4980). Additional clinical research in obese adults with type 2 diabetes shows that eating whole grain oats 50-100 grams daily in place of other carbohydrates reduces postprandial blood glucose by 19-27 mg/dL when compared with other carbohydrates in a healthy diet. After 1 year, the groups consuming 50 grams and 100 grams of oats had an additional 0.48% and 0.64% reduction in HbA1c, respectively, when compared with the regular healthy diet group (97520). There is also some evidence that consuming oats 50 grams daily, containing 25 grams of soluble fiber, might be more effective for improving glycemic control and decreasing hyperinsulinemia than the standard moderate fiber diet recommended by the American Diabetes Association (ADA) (6266). Oats have also been evaluated in adolescents with type 1 diabetes. One very small clinical study shows that taking 50 grams of a specific oat product (Betaglucare), providing beta-glucans 6 grams, in three divided doses daily for one week is beneficial for glycemic control and variability when compared with a standard diet without beta-glucans or with taking only 25 grams of the product daily. Maximal, mean, and pre- and post-meal blood glucose levels were modestly lower, and minimal blood glucose levels were modestly higher. Most measures of glycemic variability were statistically different, although there were no differences in the duration of hypoglycemia or hyperglycemia between groups (105261). Oats have also been evaluated in patients with gestational diabetes. A randomized, controlled trial shows that taking 30 grams of a specific oat bran product (OAB; Golden Light Cup Company) orally twice daily at lunch and dinner for 4 weeks improves mean fasting blood glucose and two-hour postprandial glucose when compared with a control group. After 4 weeks, the mean fasting blood glucose and 2-hour postprandial glucose in the treatment group were 85 mg/dL and 104 mg/dL, respectively, compared with 93 mg/dL and 117 mg/dL, respectively, in the control group (107751). The validity of this study is limited by the short treatment duration and lack of follow-up.
• Gastric cancer. A diet rich in soluble fiber, such as that found in oats, might reduce the risk of gastric cancer. Details: Observational research has found that consuming a diet that includes cereal fiber, such as oats and oat bran, might reduce the incidence of gastric cancer (10435).

POSSIBLY INEFFECTIVE

• Colorectal cancer. Regular consumption of oats does not seem to reduce the risk of colorectal cancer. Details: Observational research has found that consuming oat bran or oats orally doesn't seem to reduce the risk of colon cancer. Additionally, consuming fiber, including oat-bran fiber, is not associated with a reduction in the risk for recurrence of colorectal adenomas (4820,5104).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. Although there is interest in using topical oats for acne, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Anxiety. Although there is interest in using oral oats for anxiety, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Atopic dermatitis (eczema). Topical colloidal oatmeal cream may be beneficial in patients with atopic dermatitis. Details: Preliminary clinical research shows that applying a cream containing colloidal oatmeal 1% daily for 2 weeks moderately reduces the severity of atopic dermatitis when compared with baseline (103344). The validity of this finding is limited by the lack of a comparator group. Other research suggests that colloidal oatmeal may be beneficial when used in combination with topical steroids. Clinical research shows that the benefits obtained from applying an ointment containing fluocinolone 0.025% to the hands for 2 weeks were better maintained in the patients who also used a cream containing colloidal oatmeal 1% during this time period and for an additional 4 weeks when compared with patients using fluocinolone and the cream base without colloidal oatmeal. Quality of life was also improved in the patients using colloidal oatmeal (103340).
• Breast cancer. Observational research suggests that regular oatmeal intake may be associated with reduced mortality from breast cancer. Details: Population research in postmenopausal patients has found that those who have eaten 50 grams of oatmeal daily prior to a breast cancer diagnosis have a 20% reduced risk of all-cause mortality in the 7 years following the diagnosis when compared with patients who have not eaten oatmeal. However, no benefit was seen when post-diagnostic oatmeal intakes were examined (103343).
• Burns. Although there is interest in using topical oats for burns, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Chronic fatigue syndrome (CFS). Although there is interest in using oral oats for CFS, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Cognitive function. It is unclear if oral oats are beneficial in healthy adults with mild memory impairment. Details: Preliminary clinical research in healthy middle-aged adults with self-reported memory decline shows that consuming a specific wild green-oats extract (Neuravena, Frutarom) 800 mg as a single dose improves overall speed, but not overall accuracy, of cognitive performance when compared with placebo. However, a higher dose of 1600 mg was ineffective (97519).
• Dry skin. It is unclear if applying lotion containing colloidal oat extract improves dry skin to a greater extent than other lotion products. Details: Preliminary clinical research shows that applying a lotion containing colloidal oat extract (Aveeno Active Naturals Skin Relief 24Hr Moisturizing Lotion, Johnson & Johnson) twice daily for 2 weeks improves itchiness, cracking, scaling, dryness, and roughness when compared to baseline in females with dry skin (91458). Additional preliminary clinical research shows that applying a colloidal oatmeal lotion to the legs twice daily for three weeks reduces skin dryness and improves skin integrity when compared to baseline in adults with dry skin (97518). The validity of these findings is limited by the lack of a comparator group.
• Exercise-induced muscle soreness. It is unclear if oral oats are beneficial for exercise-induced muscle soreness. Details: A small clinical trial shows that eating two cookies containing oat flour 60 grams daily for 8 weeks reduces muscle soreness 48 or 72 hours after downhill running when compared with baseline (103341).
• Fat redistribution syndrome. It is unclear if oral oats are beneficial for fat redistribution syndrome. Details: Consumption of a high fiber diet, including oats, with adequate energy and protein might prevent fat deposition in patients with HIV. A one-gram increase in total dietary fiber may decrease the risk of fat deposition by 7% (12517).
• Gallbladder disease. Although there is interest in using oral oats for gallbladder disease, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Hypertension. It is unclear if oral oats are beneficial for hypertension. Details: A meta-analysis of 21 clinical studies in healthy adults and those with a variety of metabolic conditions including hypertension shows that consumption of oat products reduces systolic blood pressure (SBP) by 3 mmHg but has no effect on diastolic blood pressure (DBP) when compared with control. Subgroup analysis suggests that consuming oat products reduces SBP by 10 mmHg in patients with hypertension at baseline. An additional subgroup analysis suggests that consuming at least 5 grams of beta-glucan-enriched oats daily or consuming oats for a duration at least 8 weeks reduces SBP and DBP (113494). Observational research has found that consumption of oats as oatmeal or oat cereal does not seem to reduce DBPor SBP in males with minor elevations in blood pressure or patients with dyslipidemia (2956,113495). A randomized, controlled trial in patients with stage 1 hypertension receiving dietary guidance shows that taking 30 grams of oat bran, providing 8.9 grams of dietary fiber, once daily with breakfast or in between meals for 3 months improves various blood pressure measures when compared with dietary guidance alone. After 3 months of treatment, 24-hour maximum SBP and DBP decreased by 14 mmHg and 11 mmHg, respectively, and office SBP and DBP decreased by 15 mmHg and 10 mmHg, respectively. Oat consumption may also have impacted antihypertensive medication use. Two patients in the control group increased doses of antihypertensive medications, whereas 6 patients in the treatment group decreased doses and 1 patient discontinued use (107750). The effect of oral oat bran on patients with stage 2 hypertension or pre-hypertension is unknown.
• Irritable bowel syndrome (IBS). Although there is interest in using oral oats for IBS, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Metabolic syndrome. Limited research suggests that oats may not be beneficial for metabolic syndrome. Details: Preliminary clinical research in adults with metabolic syndrome shows that adding oat bran 40 grams daily for 6 weeks to a low-calorie diet does not reduce the incidence of metabolic syndrome. Oat bran also does not improve body weight, blood pressure, low-density lipoprotein (LDL) cholesterol, triglycerides, or blood glucose levels when compared with a low-calorie diet alone in patients with metabolic syndrome (103342).
• Osteoarthritis. Although there is interest in using oral oats for osteoarthritis, there is insufficient reliable information about the clinical effects of oats for this condition.
• Pruritus. Applying oat lotion topically may improve some types of pruritus. Details: Preliminary clinical research shows that applying an oat lotion (Espanol) twice daily for up to 2 weeks can decrease itching intensity by about 20% when compared to baseline in patients with pruritus associated with chronic kidney disease (uremic pruritus). This decrease is similar to the effects of applying vinegar 5% solution or taking hydroxyzine 10 mg orally. However, applying the oat lotion does not appear to decrease the frequency of itching (91457).
• Psoriasis. Although there is interest in using topical oats for psoriasis, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Rheumatoid arthritis (RA). Although there is interest in using oral oats for RA, there is insufficient reliable information about the clinical effects of oats for this purpose.
• Stroke. It is unclear if oral oats are beneficial for reducing the risk of stroke. Details: Population research suggests that consuming oatmeal for breakfast once weekly might reduce the incidence of stroke by a small amount when compared with consuming white bread or eggs for breakfast (103337).
• Ulcerative colitis. Oral oats have only been evaluated in combination with other ingredients; their effect when used alone is unclear. Details: Preliminary clinical research shows that taking a specific oat-based product (Profermin, Nordisk Rebalance) containing fermented oat flour, Lactobacillus plantarum, barley malt flour, and lecithin, 250 mL orally twice daily for 8 weeks, reduces disease activity and increases remission in about two-fold more patients with relapsing ulcerative colitis, when compared with treatment with a specific nutritional beverage (Fresubin Original, Fresenius Kabi) (90271).
• Wound healing. Although there is interest in using topical oats for wound healing, there is insufficient reliable information about the clinical effects of oats for this purpose. More evidence is needed to rate oats for these uses.

(Read more about OATS)

POSSIBLY EFFECTIVE

• Anxiety. Oral passion flower has a long history of use as a sedative and may improve symptoms of anxiety in some patients. Details: Preliminary clinical research shows that taking a specific dried alcoholic extract of passion flower (Sedanxio, Tilman SA) 400 mg orally twice daily for 2-8 weeks reduces the severity of non-specific anxiety when compared to baseline (88198). The validity of this finding is limited by the lack of a placebo group. Passionflower has also been evaluated as an adjunct to conventional medication. One clinical small study in patients with generalized anxiety disorder shows that taking a specific passion flower extract (Pasipay, Iran Darouk Pharmaceutical Company) 15 drops three times daily along with sertraline 50-100 mg daily for one month reduces anxiety when compared with taking sertraline alone (95036). Passion flower has also been compared to conventional treatments. One preliminary clinical study shows that taking passion flower extract 90-180 mg daily reduces symptoms of non-specific anxiety when compared to baseline, and seems to be comparable to taking mexazolam (15391). A small clinical study in patients with generalized anxiety disorder shows that taking a specific passion flower extract (Pasipay, Iran Darouk Pharmaceutical Company) 45 drops orally once daily for 28 days reduces anxiety similarly to oxazepam 30 mg daily. However, passion flower appears to have a slower onset of action than oxazepam (8007). This finding is limited because it did not utilize a therapeutic dosing regimen for oxazepam, which is given 3-4 times daily to account for its short half-life. Passion flower has also been studied in combination with other ingredients. A small clinical study in healthy adults shows that taking a combination of herbal extracts containing passion flower 40 mg, valerian root, black horehound, and hawthorn (Euphytose, Bayer HealthCare) 6 times daily with meals for 14 days reduces anxiety and sympathetic and autonomic nervous system activation in response to a psychosocial stressor when compared with placebo (111222). It is unclear if these effects are due to valerian, other ingredients, or the combination.
• Insomnia. Moderate-sized clinical studies suggest that oral passion flower may modestly improve total sleep time in patients with insomnia; however, its effects on sleep latency and maintenance are mixed. Details: A moderate-sized clinical study in adults in India with insomnia and stress shows that taking passion flower extract 600 mg daily at bedtime for 30 days increases total sleep time by about 30 minutes and reduces both the time to fall asleep and wake time after sleep onset by about 10 minutes when compared with placebo (114529). The validity of these findings is limited by lack of reporting on baseline use of medications or other substances which may impact sleep and exclusion of patients with severe insomnia. Another moderate-sized clinical study in adults with insomnia shows that taking passion flower extract 60 mg every evening before bedtime for 2 weeks increases total sleep time by around 23 minutes, but doesn't seem to improve sleep efficiency, sleep latency, or awakening after sleep onset, when compared with placebo (102866). Additionally, a smaller clinical study in young adults with mild fluctuations in sleep quality shows that drinking tea prepared by steeping passion flower aerial parts 2 grams in 250 mL of boiling water for 10 minutes every evening, about an hour before bedtime for 7 nights, improves subjective ratings of sleep quality, but not other sleep parameters, when compared with placebo (parsley tea) (17374). Passion flower has also been studied in combination with other ingredients. One small clinical study in adults with primary insomnia shows that taking a specific combination product containing passion flower 80 mg, valerian 300 mg, and hops 30 mg (NSF-3, M/s Tablets India) orally at bedtime for 2 weeks yields similar effects on subjective measures of sleep as zolpidem 10 mg nightly (88193).
• Pre-procedural anxiety. Oral passion flower modestly reduces preoperative anxiety. Details: Two small clinical studies in adults awaiting dental surgery or inguinal hernia repair surgery shows that taking a specific passion flower extract (Pasipay, Iran Darouk Pharmaceutical Company) reduces preoperative anxiety when compared with placebo. Passion flower extract was given as 20 drops or 500 mg 90 minutes prior to surgery, with or without another dose on the evening before surgery (88195,88196). Another small clinical study shows that drinking 5 mL of syrup containing passion flower aqueous extract (Passiflora syrup, Sandoz) 700 mg orally 30 minutes before epidural catheter insertion for inguinal hernia repair surgery seems to attenuate anxiety; the placebo group experienced a significant increase in anxiety (88194). This finding is limited because there were no statistical comparisons conducted between groups. Passion flower has also been compared with conventional medications. Three clinical studies show that taking passion flower prior to dental surgery decreases preoperative anxiety similarly to oral midazolam 15 mg. One study used passion flower 260 mg, administered 30 minutes prior to the surgery (95038), the second used 500 mg, administered 60 minutes prior (104206), and the third used 600 mg, administered 45 minutes prior (110014). Of the two studies that evaluated patient preference, patients in one study preferred midazolam, possibly due to its ability to cause perioperative amnesia (95038), whereas there was no preference in the other study (110014). Another clinical study shows that taking passion flower 1000 mg one hour prior to elective minor or moderate surgery reduces preoperative anxiety similarly to melatonin 6 mg; however, passion flower seems to cause more cognitive impairment than melatonin (95037).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Adjustment disorders. Oral passion flower has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One clinical study in patients with adjustment disorder with anxious mood shows that taking two tablets of a specific combination product (Euphytose, Bayer Healthcare) three times daily seems to decrease anxiety symptoms when compared with placebo. One tablet contains the dry extracts of passion flower 40 mg, valerian 40 mg, hawthorn 10 mg, and black horehound 10 mg, as well as the caffeine-containing stimulant herbs kola nut 15 mg and guarana 15 mg (6250). It is unclear if this effect is due to passion flower, other ingredients, or the combination.
• Alcohol use disorder. Oral passion flower has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults experiencing alcohol withdrawal symptoms shows that taking one capsule of a combination product (Relief) three times daily for 15 days reduces the frequency of excessive sweating, reduces serum liver enzyme levels, and improves appetite and quality of life when compared to baseline. One capsule contains passion flower extract 30 mg, black seed extract 100 mg, cocoa extract 90 mg, radish extract 165 mg, and saffron extract 15 mg (97280). The validity of these findings is limited by the lack of a comparator group.
• Attention deficit-hyperactivity disorder (ADHD). It is unclear if oral passion flower is beneficial in patients with ADHD. Details: A small clinical trial in children aged 6-13 years with ADHD shows that taking tablets of passion flower (Pasipay, Iran Darouk Pharmaceutical Company) 0.02 mg/kg orally twice daily for 8 weeks reduces parent and teacher ratings of ADHD symptoms no better than taking methylphenidate (0.5 mg/kg twice daily) (88197).
• Benzodiazepine withdrawal. It is unclear if oral passion flower is beneficial for benzodiazepine withdrawal. Details: A moderate-sized observational study in adults with depression or anxiety on antidepressants undergoing a benzodiazepine taper after chronic benzodiazepine use suggests that taking a specific dry extract of passion flower (Tractana, Baldacci) 200-600 mg daily for 3 months is associated with a faster benzodiazepine dose reduction and greater percentage of patients with at least 50% reduction or complete benzodiazepine discontinuation after 1 and 3 months from taper initiation when compared with control (111651). The validity of these effects is limited by a lack of placebo group and the retrospective observational study design.
• Congestive heart failure (CHF). Oral passion flower has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in patients with mild CHF shows that taking a combination of passion flower and hawthorn extracts 2 mL three times daily for 6 weeks increases six-minute walking distance when compared with placebo. However, it does not appear to improve exercise capacity on a bicycle ergometer test (19201). It is unclear if this effect is due to passion flower, hawthorn, or the combination. Additionally, hawthorn has been evaluated alone for the management of CHF, with some research suggesting that although it may improve symptoms, it may also be associated with worsened clinical outcomes.
• Fibromyalgia. Although there is interest in using oral passion flower for fibromyalgia, there is insufficient reliable information about the clinical effects of passion flower for this condition.
• Menopausal symptoms. Although there is interest in using oral passion flower for menopausal symptoms, there is insufficient reliable information about the clinical effects of passion flower for this purpose.
• Muscle cramps. Although there is interest in using oral passion flower for muscle cramps, there is insufficient reliable information about the clinical effects of passion flower for this purpose.
• Neuropathic pain. Although there is interest in using oral passion flower for neuropathic pain, there is insufficient reliable information about the clinical effects of passion flower for this condition.
• Opioid withdrawal. It is unclear if oral passion flower helps to prevent opioid withdrawal. Details: A small preliminary clinical study in adults who are completing an inpatient withdrawal program for opioid addiction shows that taking passion flower liquid extract 60 drops, in combination with clonidine 0.8 mg daily, is better than clonidine alone when used for reducing symptoms such as anxiety, irritability, insomnia, and agitation. However, the combination is no better than clonidine alone for reducing physical symptoms such as tremor and nausea (2303).
• Seizures. Although there is interest in using oral passion flower for seizures, there is insufficient reliable information about the clinical effects of passion flower for this condition.
• Stress. It is unclear if oral passion flower reduces stress. Details: A moderate-sized clinical study in adults in India with stress and insomnia shows that taking passion flower 600 mg daily at bedtime for 30 days modestly reduces stress when compared with placebo (114529). It is unclear how changes in stressors over the course of the study may have affected results. Additionally, a small clinical study in healthy adults shows that taking a specific combination product (Relaxane, Max Zeller Söhne AG) containing passion flower 90 mg, lemon balm 50 mg, valerian 90 mg, and butterbur 90 mg three times daily for 3 days modestly reduces subjective anxiety scores during social stress testing when compared with placebo or no treatment (97276). It is unclear if this effect is due to passion flower, other ingredients, or the combination. More evidence is needed to rate passion flower for these uses.

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EFFECTIVE

• Zinc deficiency. Orally or intravenously, zinc is effective for treating and preventing zinc deficiency. Details: Taking zinc orally or intravenously prevents and treats zinc deficiency (2619). However, routine zinc supplementation is not recommended (403). Zinc deficiency requiring supplementation may occur in patients with severe diarrhea, malabsorption syndromes, liver cirrhosis, and alcoholism; after major surgery, renal failure, and dialysis; or during long-term administration of total parenteral nutrition (3900,24321). Zinc supplementation (136 mg of elemental zinc per day) in patients with cirrhosis and zinc deficiency seems to improve liver function and glucose tolerance, possibly by increasing insulin-like growth factor (8624,87520).

LIKELY EFFECTIVE

• Diarrhea. Oral zinc reduces duration and severity of acute diarrhea in malnourished children. Doses of 5-20 mg seem to be effective, while 5-10 mg daily is less likely to cause vomiting. Details: Most research, including meta-analyses and over 30 clinical trials, show that taking zinc orally reduces the duration and severity of acute and persistent diarrhea in malnourished or zinc-deficient children, but not in well-nourished children (87236,96074). Most studies have been conducted in Bangladesh and India, so it is unclear if these findings are generalizable to other geographic locations. The most comprehensive meta-analysis of clinical studies in children older than 6 months shows that zinc supplementation reduces the duration of acute diarrhea by about 11 hours and the duration of persistent diarrhea by about 16 hours when compared with placebo. However, zinc does not seem to reduce the duration of acute diarrhea in children younger than 6 months. Zinc supplementation seems to have the greatest benefit in children with clear malnutrition and diarrhea. In these children, zinc reduces diarrhea duration by about 26 hours and reduces the risk of diarrhea persisting through days 3, 5, and 7 by 18% to 24% when compared with placebo. There was no clear benefit of using zinc in a specific dose or salt form. The most common dose of zinc was 20 mg daily and salt forms included zinc sulfate, gluconate, and acetate (96074). Also, a large clinical trial in children with acute diarrhea shows that taking zinc 5 or 10 mg daily for 14 days is non-inferior to taking 20 mg. Furthermore, zinc 5 or 10 mg results in a respective 29% and 19% lower risk of vomiting within the first 30 minutes when compared with zinc 20 mg (104045). It's unclear whether zinc supplementation reduces mortality in children with diarrhea. A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of mortality from diarrhea by 15% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). However, many studies were conducted in hospitals where rates of mortality are low and were not adequately powered to determine whether zinc has an effect on mortality in children with acute diarrhea (87210,96074,106239).
• Wilson disease. Taking zinc orally improves symptoms of this condition. Details: Zinc acetate (Galzin) is an FDA-approved orphan drug for treating this condition. Zinc blocks copper absorption and increases copper elimination in the stool of people with Wilson disease (2692,2693,87327). Small clinical studies suggest that taking zinc after 8 weeks of treatment with tetrathiomolybdate alone can improve Kayser-Fleischer rings, urine copper levels, and neurological symptoms for up to 6 years post-treatment (63588,87491).

POSSIBLY EFFECTIVE

• Acne. Orally, zinc might help to reduce symptoms of acne. However, it's unclear how oral zinc compares to conventional acne treatments. Topical zinc doesn't seem to be beneficial if used alone. Details: Observational research has found that people with acne seem to have lower zinc levels in the serum and skin (104056). A meta-analysis of small, low quality clinical trials suggests that taking zinc sulfate or zinc gluconate 137-300 mg 2-3 times daily by mouth can modestly improve acne when compared with placebo (104056). However, not all individual trials show benefit (87002,104056). So far, it is not clear how oral zinc compares to other treatments. Trials comparing zinc sulfate with various tetracyclines have yielded conflicting results (6505,6506,86946,106233). One large open-label clinical trial shows that taking zinc sulfate 200 mg twice daily for 12 weeks is at least as effective as lymecycline 300 mg daily for reducing acne severity. Quality of life related to acne was modestly improved in the patients using zinc sulfate (106233). However, in another clinical trial, a 3-month treatment of oral zinc gluconate 30 mg daily reduced the number of acne lesions from baseline, but was not as effective as minocycline (86946). When applied topically, clinical research shows that zinc does not help treat acne when compared with placebo (87297,104056). However, when used in combination with erythromycin, topical zinc seems to result in improvement (819,820,2687,2688).
• Acrodermatitis enteropathica. Oral zinc seems to improve symptoms of this rare genetic disorder. Details: Multiple case reports have found that taking oral zinc seems to help improve symptoms of acrodermatitis enteropathica, a rare disorder (821,2689,2690,2691). One case report in a female with necrolytic acral erythema and hepatitis C suggests that adding oral zinc sulfate 225 mg twice daily to interferon alfa-2b for 6 months contributed to resolving all lesions. Necrolytic acral erythema is categorized in the family of necrolytic erythemas that includes acrodermatitis enteropathica (6192).
• Age-related macular degeneration (AMD). Oral zinc, especially in combination with antioxidant vitamins, seems to slow the progression of AMD. Details: Clinical research shows that taking elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily reduces the odds of progression to advanced AMD by 28%. In patients with more severe AMD, this combination reduced the odds of progression to advanced AMD by 34%. This combination also reduced the odds of visual acuity loss by 27% in patients with severe AMD (7303,11326). However, there is contradictory evidence about the effects of zinc plus antioxidants on visual acuity loss or the progression to advanced AMD in low-risk patients with AMD (6583,6584,7303). Some clinical evidence shows that, when taken without antioxidant vitamins, zinc supplementation does not slow the progression of existing AMD (6580,90069). However, a subgroup analysis of results from a large clinical trial that included patients with intermediate or advanced AMD suggests that the effect of zinc on AMD progression might vary depending on a patient's genetic predisposition. Complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) are two genes for which specific variations (i.e., risk alleles) have been associated with an increased risk of AMD. Results from the retrospective subgroup analysis suggest that zinc supplementation may DECREASE the progression of AMD in patients with ARMS2 risk alleles and INCREASE the progression of AMD in patients with CFH risk alleles (90193). However, some experts question the results from this analysis due to the retrospective nature of the study (93045). Another retrospective analysis of similar data found that only zinc plus antioxidants, but not zinc alone, was beneficial for slowing the progression of AMD, regardless of the patient's genotype (93046). Consequently, the American Academy of Ophthalmology does not currently recommend routine genetic screening to determine which patients would benefit from zinc, antioxidants, or the combination. Instead, patients with intermediate or advanced AMD are recommended to take an antioxidant and zinc supplement similar to those used in the Age-Related Eye Disease Study (AREDS) and the Age-Related Eye Disease Study 2 (AREDS2) (93047). Large scale population studies suggest that increasing dietary intake of zinc might reduce the risk of developing AMD (6579,14257).
• Child growth. Oral zinc seems to increase growth when taken by children and improve infant growth in the first year of life when taken by pregnant adults. Details: A meta-analysis of 8 clinical studies in healthy children over 2 years old shows that taking supplemental zinc 5-15 mg daily for 6-56 weeks modestly increases height and weight when compared with placebo. This analysis also shows that taking zinc may improve height for age, but not weight for age when compared with placebo (112474). Most of these studies were conducted in developing countries; results may not apply elsewhere. Another clinical study in pregnant adults in Peru shows that taking zinc 15 mg daily in addition to iron and folic acid, starting during the first or second trimester and continuing up to one month after delivery, modestly improves growth measures of infants at one year when compared with taking iron and folic acid alone. Improved growth measures include body weight, calf and chest circumference, and calf muscle area (87130).
• Common cold. Oral zinc seems to help treat cold symptoms in adults. However, it is unclear if zinc is beneficial for common cold prevention. Details: Using zinc oral lozenges seems to be beneficial in helping TREAT the common cold in adults. The majority of clinical trials and analyses of clinical research show a significant decrease in the duration of symptoms of the common cold when adults take zinc gluconate or zinc acetate lozenges providing 9-24 mg of elemental zinc per dose. It is recommended that lozenges be taken every 2 hours while awake, starting within 48 hours of symptom onset for a total daily dose of at least 75 mg in order to attain a mean cold duration reduction of 3 days (333,334,335,337,6703,6705,87501,92212,106902). However, not all studies have been positive (333,338,339,6522,6700,87512). The reasons for these different findings are not clear, but might be due to differences in zinc formulations and doses and study methodologies. In some cases, flavoring agents such as citric acid, mannitol, and sorbitol might chelate zinc and decrease zinc ionization. Since ionization is thought to be necessary for zinc activity, a decrease in zinc ionization could decrease effectiveness (300,340,6522). Some of the positive studies have also been criticized for inadequately blinding the unpleasant, distinctive taste of zinc (6522,6706). Allergy and smoking status do not appear to impact the efficacy of zinc acetate lozenges (92212). Overall, zinc products may be beneficial for modestly reducing the duration of symptoms of the common cold in adults, but adverse effects such as bad taste and nausea may limit their usefulness (18216). There is conflicting evidence for the use of oral zinc products to PREVENT colds. Some clinical research suggests that taking zinc prophylactically does not prevent the common cold in adults (10780,10784) or children (341). However, other clinical research suggests that administering zinc gluconate lozenges can reduce the incidence of colds in children and adolescents (10803,86972). In a meta-analysis of 28 randomized controlled trials with a total of 5446 participants, oral zinc prevented 5 viral upper respiratory tract infections per 100 person months of zinc use when compared with placebo, with a number needed to treat (NNT) of 20 (106902). Intranasal zinc is not recommended for the prevention or treatment of the common cold due to the risk for anosmia. See the Adverse Effects section for more information. Some research shows that zinc nasal spray (as a sulfate, gluconate emulsion, or gluconium gel) reduces the severity and duration of cold symptoms; however, other research has found no effect (6471,8628,8629,10247,87035). Zinc nasal spray does not seem to prevent experimentally-induced colds (8628).
• Coronavirus disease 2019 (COVID-19). While oral zinc does not seem to speed recovery from COVID-19 in non-hospitalized patients, an analysis of a small number of studies suggests that oral or intravenous zinc might reduce the risk of death in hospitalized patients with COVID-19. Details: A small observational study in patients with COVID-19 has found that lower serum zinc levels are associated with worse clinical outcomes, such as admission to the intensive care unit (ICU) and death, when compared with higher zinc levels (105681). Another small observational study has found that 96% of patients with confirmed COVID-19 were zinc-deficient based on plasma levels of zinc, and that these patients had lower plasma zinc levels than a group of individuals without COVID-19. However, plasma zinc concentrations were only weakly correlated with length of hospital stay and there was no correlation with morbidity or mortality (106236). One clinical study in adult outpatients with COVID-19 shows that taking zinc gluconate 50 mg daily at bedtime, alone or with vitamin C (ascorbic acid) 8000 mg daily, for 10 days does not reduce symptom severity when compared with standard care (104450). This study was terminated prior to complete enrollment due to a lack of effect with zinc and/or vitamin C supplementation. Limitations of this study include a lack of placebo control and blinding. Zinc supplementation also does not appear to enhance the clinical efficacy of hydroxychloroquine in patients with confirmed COVID-19 infection. Taking zinc sulfate 220 mg twice daily during a 6-day course of hydroxychloroquine does not improve the clinical recovery rate, reduce the mortality rate, or reduce the need for mechanical ventilation when compared with hydroxychloroquine alone (104818). Other research has evaluated zinc in hospitalized patients. Multiple meta-analyses of small and low-quality clinical studies, including randomized controlled trials and retrospective studies, involving hospitalized patients with COVID-19 shows that supplementation with oral or intravenous zinc is associated with a 29% to 43% reduction in the odds of in-hospital mortality when compared with control (109451,110631). However, in one meta-analysis, the odds of 30-day mortality were not different between groups (110631). These meta-analyses did not elevate the most effective form, dose, frequency, or duration of zinc supplementation (109451,110631). Additionally, a retrospective study in adults admitted to the ICU with COVID-19 has found that those who received oral zinc sulfate, 220 mg daily for a median of 11 days, had a lower 30-day mortality rate when compared with those who did not receive zinc. However, there was no difference in hospital length of stay or in-hospital mortality (106903).
• Depression. Oral zinc seems to be beneficial when used in combination with antidepressant treatments. Details: Population research has found that higher zinc levels and higher dietary intake of zinc are associated with a 28% lower incidence of depression (90227,97139,104057). Oral zinc seems to be beneficial as an adjunct therapy in depression. A meta-analysis of small, low-quality studies in patients with major depression shows that taking zinc in addition to antidepressant therapy is associated with modestly improved depression symptoms when compared with antidepressant therapy alone (104044). Clinical studies used zinc doses of 7-25 mg daily for up to 12 weeks (86985,90221,104044). One small clinical study also shows that adding zinc to imipramine therapy might improve depression that was previously resistant to antidepressant treatment (87158). One clinical guideline also provisionally recommends use of zinc 25 mg elemental orally daily to treat patients with depression based on low-quality evidence. This guideline recommends use of chelated or picolinate zinc products over other forms of zinc (110318).
• Diabetes. Oral zinc might modestly improve glycemic control in some patients. Details: A meta-analysis of 12 clinical studies in patients with diabetes shows that taking zinc supplements reduces fasting blood glucose by up to 20 mg/dL and glycated hemoglobin (HbA1c) by 0.35% when compared with control. However, when only high quality studies were included, the reduction in fasting blood glucose dropped to 12 mg/dL. Zinc seems to only have glycemic benefit in patients living in the Eastern hemisphere, and not the Western hemisphere. Also, glucose reduction seems to be higher with inorganic zinc formulations at doses of at least 30 mg daily taken for at least one month (104080). Zinc has also been evaluated for improving lipid parameters in patients with diabetes. A meta-analysis of nine studies in patients with diabetes shows that taking zinc reduces triglycerides by 17 mg/dL, but does not seem to affect low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol levels, when compared with placebo (104041). The findings from these meta-analyses are limited by the high heterogeneity and small size of the included studies. Zinc has also been studied for gestational diabetes. Some clinical research in patients with gestational diabetes shows that taking zinc gluconate for 6 weeks, starting at 24-28 weeks' gestation, reduces fasting plasma glucose levels by about 10% and improves insulin resistance by 14% when compared to baseline (96072). However, taking zinc gluconate does not reduce the need for caesarean section or insulin therapy, or improve infant outcomes, such as size or health at birth, in these patients (96073).
• Diaper rash. Topical and oral zinc seem to reduce the incidence and severity of diaper rash in infants. Details: Clinical research shows that administering oral zinc gluconate 10 mg daily for 4 months can reduce the incidence of diaper rash in infants when compared with placebo (87281). Other clinical research shows that applying 47% zinc oxide paste to affected areas for 5 days can improve the healing of diaper rash. However, the effect of zinc oxide paste is inferior to eosin 2% solution (86918).
• Gingivitis. Topical zinc seems to reduce the development of gingivitis. Details: While some clinical research shows that zinc, in combination with triclosan, does not prevent plaque and gingivitis (24093,87020), most clinical research shows that using zinc toothpaste or mouthwash, alone or in combination with triclosan, can prevent plaque accumulation, gingivitis, or the formation of calculus (6523,6524,6525,6526,6527,6528,6529,87418,87507). However, most studies used zinc citrate in combination with triclosan, which is not available in the US (6523). For treating existing plaque, calculus, and gingivitis, some clinical research suggests that using zinc citrate 0.5% toothpaste three times daily for 3 months reduces calculus scores by 14% when compared with placebo (87205). However, other evidence suggests that stannous fluoride 0.454% toothpaste is more effective than zinc citrate 0.75% toothpaste for reducing plaque levels (87136).
• Halitosis. Oral zinc seems to reduce halitosis when taken as a gum, mouth rinse, or candy. Details: Clinical research shows that chewing zinc-containing gum reduces volatile sulfur compounds and related odor levels when compared with placebo gum in patients with moderate to severe halitosis (87538). Clinical research also shows that using one of two mouth rinses (Halita, which contains 0.05% chlorhexidine and 0.14% zinc lactate, or Meridol, which contains 0.025% fluoride plus 0.2% zinc lactate) improves breath odor and volatile sulfur compounds by approximately two-fold when compared with mouth rinse containing only 0.05% fluoride or chlorhexidine 0.12% (90206). Additional clinical research shows that sucking a candy containing abrasive substances and zinc gluconate 0.5% or candy containing abrasive substances plus zinc 0.25% and propolis 1% improves breath malodor two- to three-fold when compared with sucking placebo candy (90196).
• Herpes labialis (cold sores). Topical zinc seems to reduce the severity and duration of cold sores. Details: Applying zinc topically seems to help treat herpes simplex infection (6538,6539,8623,11051). Zinc sulfate seems to reduce the severity and duration of symptoms in both orolabial and genital herpes (6538,6539). Zinc oxide (0.3%) in combination with glycine cream applied topically every 2 hours to facial and circumoral herpes seems to reduce symptoms such as blistering, soreness, itching, and tingling. It can also reduce the duration of lesions from 6.5 days to 5 days when treatment is begun within 24 hours of onset of symptoms (8623). A specific combination product containing zinc oxide and L-lysine plus 14 other ingredients (Super Lysine Plus +) also seems to help decrease symptoms and duration of herpes lesions when applied topically every 2 hours (11051). However, zinc may not be effective for recurrent herpes simplex infections. In one clinical study, applying zinc sulfate 0.0025% or 0.05% solution to affected areas did not reduce the frequency, severity, or duration of herpes episodes when compared with a placebo solution in patients experiencing more than five episodes per year (87330).
• Hypogeusia. Oral zinc might improve taste disturbance and taste acuity in people with hypogeusia of various etiologies. Details: A meta-analysis of low-quality studies in patients with taste disorders that are idiopathic or due to zinc deficiency shows that taking oral zinc modestly improves taste acuity when compared with placebo (104055). Studies tested zinc gluconate, zinc sulfate, zinc acetate, and zinc-carnosine as Polaprezinc (Promac, Zeria Pharmaceutical Co., Ltd.), containing 17-68 mg elemental zinc, daily for up to 12 weeks (104055). Zinc also might improve hypogeusia conditions unrelated to zinc deficiency, such as gustin/carbonic anhydrase VI deficiency, captopril-induced taste disturbances, hypogeusia due to chronic renal failure, and post-traumatic olfactory disorder (6543,6544,104055). It also seems be beneficial in radiation-induced dysgeusia. A meta-analysis of three small clinical trials shows that oral zinc reduces the risk of radiation-induced dysgeusia by 28%, but does not improve taste acuity when compared with placebo (104043). However, patients with hypogeusia from other causes may not benefit. Zinc supplementation does not seem to improve taste perception when compared with placebo in patients with acetazolamide-induced taste dysfunction or chemotherapy-induced taste dysfunction (87388,90214).
• Leishmania lesions. Oral zinc and intralesional injections of zinc might improve healing of these lesions. Details: Clinical research shows that taking zinc sulfate 2.5-10 mg/kg orally in three divided doses daily, improves the cure rate of cutaneous leishmania lesions after 45 days when compared with no treatment (86935). Other clinical research shows that intralesional injections of zinc sulfate 2% solution for 6 weeks improves cure rates of cutaneous leishmania lesions when compared with no treatment (6587). However, intralesional injections with zinc sulfate solution does not appear to be more effective than intralesional injections of meglumine antimoniate (Glucantime), hypertonic saline, or sodium stibogluconate (6587,86996,87008).
• Leprosy. Oral zinc seems to be beneficial when used in combination with anti-leprosy drugs. Details: Zinc levels appear to be reduced in people with leprosy. Early clinical research suggests that the addition of zinc improves tolerance of the anti-leprosy drug regimen and might allow for lowering or eliminating steroid doses in erythema nodosum leprosum, a severe form of leprosy (6534,6535,6536,6537).
• Low birth weight. Oral zinc supplementation seems to improve growth in low birth weight infants. Whether oral zinc can improve other outcomes, including mortality, is unclear. Taking oral zinc during pregnancy does not seem to reduce the risk of having a low birth weight infant. Details: While there is some mixed evidence regarding the effects of zinc supplementation on weight gain and length in infants born with low birth weight (87172,87452,90229), a meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, increases weight by around 380 grams, length by around 3 cm, and head circumference by around 0.6 cm when compared with control (109455). There is also mixed evidence regarding the effect of zinc supplementation on other outcomes in low birth weight infants. A large clinical trial in full-term, underweight infants aged 1-6 months in developing countries shows that adding zinc to nutritional supplementation reduces the risk of mortality by about 68% when compared with nutritional supplementation not containing zinc (8920). A small clinical trial in very low birth weight preterm infants born in an industrialized country shows that adding zinc to multivitamin supplementation appears to reduce the occurrence of necrotizing enterocolitis and mortality. However, adding zinc does not appear to prevent late-onset sepsis, bronchopulmonary dysplasia, or retinopathy of prematurity (90229). A meta-analysis of these trials and two other studies in low birth weight infants shows that supplementation with zinc reduces the risk of all-cause mortality by 52% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). Another small clinical study in low birth weight and preterm infants born in a developing country shows that zinc supplementation seems to improve alertness and attention when compared with placebo (97140). However, a meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, does not improve mental or psychomotor development or reduce the risk of mortality, hospitalization, acute respiratory infection, or sepsis when compared with control (109455). Some of these discrepant findings may be due to differences in patient populations (hospitalized, non-hospitalized), milk sources (breastfed, formula-fed, or both), and duration of follow-up. The effect of zinc intake or supplementation during pregnancy has also been evaluated. Population research has found that low dietary intake of zinc during pregnancy is associated with low birth weight in infants; similarly, zinc supplementation is associated with increased infant weight at birth (87471,105678). However, a meta-analysis and a large clinical study show that zinc supplementation during pregnancy does not reduce the risk of having a low birth weight infant (97142,105679). Reasons for the discrepancies may be due to differing zinc status prior to supplementation. Also, numerous factors contribute to the risk of low birth weight, which may confound research on the use of zinc supplementation alone.
• Peptic ulcers. Oral zinc seems to treat and prevent peptic ulcers. Details: Taking zinc orally seems to help treat and prevent peptic ulcers (6588,6589,6591). Some clinical research shows that zinc acexamate improves peptic ulcers when compared with placebo (6589,87285), and seems to be as effective as H2-receptor antagonist drugs (6589,87533). It is not known if other zinc salts are effective.
• Pneumonia. Oral zinc might reduce the risk for pneumonia in children, but it doesn't seem to improve symptoms in children that already have pneumonia. Details: A meta-analysis of four clinical studies shows that giving zinc supplements to children, ages 3 months to 5 years living in developing countries, some of whom were undernourished, reduces the risk of pneumonia incidence by 21% when compared with placebo (104047). Another meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of pneumonia mortality by 21% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). The research on TREATING existing pneumonia in children is inconsistent. Most meta-analyses and clinical studies in children ages 2 months to 5 years with severe pneumonia show that taking elemental zinc in addition to antibiotic therapy does not improve symptom resolution or the time to recovery when compared with antibiotic therapy alone. Zinc also does not seem to reduce mortality in these patients (87248,90197,96080,98131,104042). However, two clinical studies in children in the same age group with pneumonia suggest that adding zinc to standard antibiotic therapy improves symptom resolution and decreases hospital stay when compared with placebo (11052,87242). Reasons for these discrepancies are not clear, but may be related to zinc status prior to treatment.
• Prematurity. Analyses of clinical studies suggest that oral zinc improves growth in premature infants. Whether zinc improves development or reduces the risk of mortality in these patients is unclear. Details: A meta-analysis of small clinical trials in hospitalized infants born prematurely suggests that receiving enteral zinc supplementation at a dose of up to 10 mg daily reduces mortality and might improve short-term weight gain when compared with placebo (105687). Another meta-analysis of small clinical studies in preterm infants shows that adding zinc to formula or to a multivitamin seems to modestly increase infant weight and height and improve motor development when compared with control (105676). A larger meta-analysis of 14 clinical trials in preterm or low birth weight infants receiving breastmilk shows that zinc supplementation, typically 5-7 mg daily started at birth and continued for up to 12 months with or without other micronutrients, increases weight by around 380 grams, length by around 3 cm, and head circumference by around 0.6 cm when compared with control. However, zinc supplementation did not improve mental or psychomotor development or reduce the risk of mortality, hospitalization, acute respiratory infection, or sepsis when compared with control (109455). These analyses are limited by imprecision as well as a high risk of bias in some of the included studies. Some of the discrepant findings may be due to differences in patient populations (hospitalized, non-hospitalized), milk sources (breastfed, formula-fed, or both), and duration of follow-up.
• Pressure ulcers. Topical zinc paste seems to work as a skin barrier and improve pressure ulcer healing. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that applying zinc oxide paste to pressure ulcers daily for 8 weeks reduces necrotic tissue and decreases the surface area of skin pressure ulcers similarly to using a topical streptokinase-streptodornase product (Varidase) (87331). Other small clinical studies show that applying zinc oxide paste to pressure ulcers daily for 8-12 weeks improves healing similarly to a hydrocolloid dressing (Duoderm) (87181) or a specific barrier film product (Cavilon No Sting Barrier Film) (87017). Oral zinc has been evaluated in combination with other ingredients for the treatment of grade II-IV pressure ulcers. Two small clinical studies in hospitalized patients shows that administering an oral nutritional supplement enriched with zinc, L-arginine, and vitamin C improves ulcer healing when compared with a standard diet (31953,87173). Also, clinical research in patients living in long-term care facilities shows that taking an oral nutritional supplement enriched in protein, zinc, L-arginine, and vitamin C daily for 9 weeks reduces ulcer area and decreases oozing when compared to baseline (32045). The validity of this finding is limited by the lack of a comparator group.
• Sickle cell disease. Oral zinc seems to improve symptoms of sickle cell disease in patients with zinc deficiency. Details: Taking zinc orally seems to help reduce symptoms of sickle cell disease in people with zinc deficiency (6594,6595,6596,8626,87343). Taking zinc supplements also seems to decrease the occurrence rate of sickle-cell crises and infections (6594,6596,90228). Additionally, zinc might reduce the number of hospitalizations for sickle cell crises, although the severity of the crises that do develop is not necessarily decreased by taking zinc supplements (6594,6596). In prepubertal children and adolescents with homozygous sickle cell disease, taking zinc seems to improve growth, height, and weight gain (8626,87403).
• Warts. Oral and topical zinc seem to improve the cure rate of cutaneous warts. Details: A small clinical study suggests that applying zinc sulfate 10% solution three times daily for 4 weeks improves plane warts, but not common warts, when compared with distilled water (87094). Another small clinical study suggests that applying topical zinc oxide 20% ointment twice daily for up to 3 months seems to have a similar cure rate as ointment containing salicylic acid 15% with lactic acid 15% (87082). Taking zinc orally may also be effective in treating warts (87227). A meta-analysis of low quality clinical studies shows that taking zinc sulfate orally improves the odds of curing cutaneous warts nearly 17-fold when compared with respective controls (87227). Preliminary clinical research in adults treated with cryotherapy for anogenital warts shows that taking zinc gluconate 30 mg orally three times daily for 2 months does not reduce the number of warts when compared with placebo (111445).

POSSIBLY INEFFECTIVE

• Alopecia areata. Oral zinc does not seem to improve symptoms of this condition. Details: Although there is preliminary evidence that suggests zinc in combination with biotin might be helpful for alopecia areata (6932), most studies indicate that zinc is not effective for alopecia areata, alopecia totalis, or alopecia universalis (6931,6932).
• Cystic fibrosis. Oral zinc does not improve cystic fibrosis symptoms or progression. Details: Clinical research shows that taking supplements providing 30-90 mg of elemental zinc for 6 weeks to one year does not improve lung function when compared with placebo in children and adolescents with cystic fibrosis (87066,87113,96079). One clinical study also shows that taking elemental zinc for one year does not reduce the number of days requiring oral or intravenous antibiotics for pulmonary infections (96079). However, one study shows that taking zinc can reduce the number of days of oral antibiotic use when compared with placebo (87113).
• HIV/AIDS. Oral zinc does not seem to improve outcomes in patients with HIV. Details: Clinical research in adult HIV patients with normal or low zinc levels shows that taking elemental zinc 12-15 mg daily orally for 18 months along with antiretroviral therapy does not improve viral load, CD4/8 counts, or mortality when compared with placebo (87036,87216,105686). In children with HIV-1, clinical research shows that administering zinc sulfate, providing 10 mg elemental zinc, daily for 6 months does not improve mortality, viral load, or CD4 counts when compared with placebo (82377).
• HIV/AIDS-related pregnancy complications. Oral zinc does not prevent pregnancy complications related to HIV infection. Details: Adding zinc 25 mg orally during pregnancy does not seem to reduce parent-to-child vertical transmission of HIV, infant mortality, birth weight, or gestational period in HIV-infected females with low zinc levels (11054,87034). Also, one clinical study in HIV-1-infected pregnant patients suggests that supplemental zinc can increase the risk of wasting, as assessed by weight and mid-upper arm circumference, by 170% when compared with placebo (87034).
• HIV/AIDS-related wasting. Oral zinc does not seem to improve HIV-related wasting syndrome. Details: A clinical study in patients with HIV-related wasting syndrome shows that taking zinc orally in combination with vitamins and albendazole does not seem to improve diarrhea or mortality when compared with taking albendazole alone (6564).
• Infant development. Oral zinc does not seem to improve infant mental and psychomotor development. Details: Clinical research, including a meta-analysis of eight studies, shows that giving zinc to infants or children at high risk for zinc deficiency does not improve mental and psychomotor development when compared with placebo (87013,90209). In another meta-analysis of studies in children whose baseline zinc status was not specified, there was no beneficial effect of zinc supplementation on mental or psychomotor development at 6 or 12 months of age (104817).
• Inflammatory bowel disease (IBD). Oral zinc does not improve symptoms of IBD. Details: Some clinical research shows that taking zinc orally does not seem to help treat IBD (6913,6915,6916).
• Influenza. Oral zinc does not seem to reduce the risk for influenza. Details: Supplemental zinc seems to improve cell-mediated immune response in elderly people (824), but it does not seem to have a significant effect on antibody response and incidence of influenza infection after the vaccine (6553,6563). Additionally, zinc supplementation in patients on hemodialysis, who have a high risk of zinc deficiency, does not seem to improve response to influenza vaccine (10809). Taking zinc supplements orally is unlikely to improve immune function in people without risk factors for zinc deficiency (10789). However, there is preliminary evidence that suggests zinc along with selenium might reduce the incidence of infections in institutionalized older patients (8921).
• Otitis media. Oral zinc does not prevent otitis media in children. Details: A meta-analysis of clinical research shows that taking elemental zinc 3-70 mg daily for up to 24 months does not prevent the occurrence of ear infections in children from low- or middle-income countries (87258).
• Pre-eclampsia. Oral zinc taken prenatally does not seem to be beneficial for pre-eclampsia prevention. Details: A meta-analysis and a large clinical study show that zinc supplementation during pregnancy does not reduce the risk of pre-eclampsia when compared with placebo (97142,105679).
• Prostate cancer. Oral zinc does not reduce the risk for prostate cancer or prostate cancer-related mortality. Details: Some epidemiological research has found an inverse relationship between dietary zinc intake and prostate cancer (96075). Also some clinical research shows that taking zinc 20 mg in combination with vitamin C 120 mg, vitamin E (alpha-tocopherol) 30 mg, beta-carotene 6 mg, and selenium 100 mcg daily for an average of 8 years might reduce the risk of prostate cancer in men with normal PSA levels; however, it does not seem to be beneficial for reducing the risk of prostate cancer in patients with PSA levels above 3 mcg/L (14135). However, some evidence raises concern that zinc might actually INCREASE the risk of prostate cancer. A large-scale population study found that taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer (10306). Another large-scale population study shows that men who take a multivitamin more than seven times per week and who also take a separate zinc supplement have a significantly increased risk of prostate cancer-related mortality (15607). Despite these studies suggesting the potential for adverse effects of zinc, a meta-analysis of mainly population research has found that there is no association between zinc intake and the risk of prostate cancer (96075).
• Psoriasis. Oral zinc does not reduce the severity of psoriasis symptoms. Details: Zinc epidermal levels are reportedly lower in people with psoriasis (6509). However, taking zinc orally does not seem to help treat psoriasis (6513,6514,6912,87363). Zinc supplementation has no effect on the psoriasis area and severity index (6513,6514).
• Rheumatoid arthritis (RA). Oral zinc does not treat symptoms of RA. Details: Multiple clinical studies in patients with RA show that taking zinc orally does not improve function or symptoms when compared with baseline or control (6517,6518,6519,87406).
• Sexual dysfunction. Oral zinc does not improve sexual function in males with chronic kidney disease (CKD). Details: Clinical research shows that zinc supplementation does not improve sexual activity or libido when compared with placebo in males with sexual dysfunction secondary to CKD (6708,6568,87220,87386,87416). In fact, one clinical study shows that taking zinc can decrease the frequency of intercourse by 76% when compared with placebo in patients with CKD-related sexual dysfunction (87220).
• Tinnitus. Oral zinc does not improve severity of tinnitus or reduce tinnitus-related disability. Details: A meta-analysis of three small clinical trials in adults with tinnitus shows that taking elemental zinc 50 mg daily for up to 16 weeks does not improve tinnitus severity, or disability from tinnitus when compared with placebo (104051).

LIKELY INEFFECTIVE

• Malaria. Oral zinc does not prevent or treat malaria in undernourished children or pregnant adults in developing countries. Details: A meta-analysis of clinical research in children or pregnant adults shows that taking zinc orally, alone or in combination with other supplements, for does not reduce the risk of malaria parasitemia (111444). A large multi-country study in zinc-deficient preschool children with acute malaria shows that taking zinc supplements does not affect fever, parasitemia, or hemoglobin when compared with placebo (10246). An even larger clinical study of over 40,000 children with malaria aged 1-36 months shows that taking zinc 5-10 mg daily orally for approximately 17 months does not reduce mortality when compared with placebo (87078). Zinc supplements also do not appear to protect against infection by Plasmodium falciparum (8638,87235,86937). However, one small study in children with low and high levels of parasitemia shows that taking zinc 10 mg daily for 46 weeks may lower the incidence of fever episodes by 38% and 69%, respectively, when compared with placebo (86937).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral zinc is beneficial in patients with age-related cognitive decline. Details: An epidemiological study based on elderly adults enrolled in the National Health and Nutrition Examination Survey (NHANES) has found that taking zinc may improve cognition in a non-linear manner. Daily doses below 9 mg and 8 mg in males and females, respectively, showed a positive association with cognitive function, but doses above that level showed no association. Additionally, high intake of both zinc and selenium was associated with improved cognition in females, but not in males (108446). Dietary intake was collected from two patient-reported 24-hour recalls and cognition was only measured once, limiting the validity of these findings.
• Alcohol-related liver disease. It is unclear if oral zinc is beneficial in patients with alcoholic-related liver cirrhosis. Details: A small clinical study in patients with alcoholic liver cirrhosis shows that taking zinc sulfate 600 mg daily for 6 weeks improves liver function, based on increased alkaline phosphatase activity and reduced serum bilirubin, when compared to baseline (87325).
• Anorexia nervosa. Oral zinc seems to improve weight gain in people with anorexia nervosa. Details: Anorexia nervosa might be linked with zinc deficiency. Small clinical trials in adolescents and adults with anorexia nervosa show that oral zinc supplements might help increase weight gain and improve depressive symptoms when compared with placebo (6905,6906).
• Arsenic poisoning. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study shows that taking zinc 4 mg in combination with spirulina extract 500 mg daily for 16 weeks can decrease skin manifestations and reduce arsenic levels in the urine and in hair of patients with chronic arsenic poisoning (18301).
• Asthenopia (eye strain). Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in adults without dry eye disease shows that taking a specific combination product containing zinc 10 mg, L-carnitine 50 mg, elderberry fruit extract 300 mg, currant 100 mg, and Eleutherococcus root 50 mg (Meramirt CM) orally once daily for 1 month improves measures of eye strain and contrast sensitivity when compared to baseline. Improvements in these measures were lacking in the control group (111295). Statistical comparison between the two groups was not reported. It is unclear if these effects are due to zinc, other ingredients, or the combination.
• Athletic performance. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in sleep-deprived recreational athletes shows that taking a combination of zinc 90 mg, magnesium 1350 mg, and vitamin B6 31.5 mg orally for 3 nights at bedtime does not improve grip strength, squat, or bench press performance when compared with placebo (113655).
• Atopic dermatitis (eczema). It is unclear if oral zinc is beneficial for alleviating eczema in children. Details: A small clinical study in children with eczema shows that taking zinc sulfate 185.4 mg orally daily for 8 weeks does not appear to improve the surface area affected and degree of erythema, symptom scores of itch and sleep disturbance, or topical steroid use when compared with placebo. Also, plasma zinc levels appear to be normal in children with eczema (6911).
• Attention deficit-hyperactivity disorder (ADHD). Oral zinc might improve certain symptoms in children with ADHD. Details: Observational research has found that lower serum zinc levels are both more prevalent in children with ADHD and are linked to worsened response to stimulant therapy (9965,9966,9967). Based on this evidence, there is some interest in using zinc to improve symptoms in children with ADHD. A meta-analysis of six small clinical trials shows that although taking zinc modestly improves overall symptoms of ADHD when compared with placebo, there is no effect on hyperactivity or inattention when these outcomes are examined separately. The sub-analyses conducted for these two separate outcomes included only 3 studies. Most, but not all, of the included studies were conducted in children also receiving methylphenidate treatment (106240). Elemental zinc, usually as sulfate, was typically used in doses of 10-40 mg daily for 6-12 weeks (11350,12060,106240). There is some evidence that zinc could be most helpful in children with a high body mass index (BMI), low zinc levels, and low free fatty acid levels (11350). It is unclear if zinc is beneficial in children who are not already taking stimulant medications. One clinical guideline also provisionally recommends against use of oral zinc to treat patient with ADHD based on low-quality evidence (110318).
• Autism spectrum disorder. It is unclear if oral zinc is beneficial in children with autism spectrum disorder. Details: One small clinical study conducted in children with autism spectrum disorder shows that taking zinc 15-30 mg orally, alone or as add-on therapy to amphetamine, does not improve attention deficit hyperactivity disorder (ADHD) symptoms when compared with placebo (98711). However, the optimal mg/kg dose of amphetamine was shown to be 37% lower for those children also taking zinc 15 mg twice daily when compared with those taking placebo (98711).
• Autoimmune thyroiditis. It is unclear if oral zinc is beneficial in children with autoimmune thyroiditis. Details: A small clinical study in children aged 3-18 years with autoimmune thyroiditis shows that taking zinc acetate 25 mg daily in addition to standard therapy for 12 weeks does not change thyroid auto-antibody levels, thyroid function tests, or oxidative stress markers when compared with standard therapy alone. However, subjects taking zinc did not require escalation in levothyroxine doses when compared with the control group control group, which did require levothyroxine dose escalation (113661).
• Behcet disease. It is unclear if oral zinc is beneficial in patients with Behcet disease. Details: A small clinical trial in patients with Behcet disease shows that taking zinc gluconate 30 mg daily for 12 weeks does not improve disease activity scores, quality of life, or measures of inflammation when compared with placebo (109453).
• Benign prostatic hyperplasia (BPH). Although there is interest in using oral zinc for BPH, there is insufficient reliable information about the clinical effects of zinc for this condition.
• Beta-thalassemia. It is unclear if oral zinc is beneficial in patients with beta-thalassemia major. Details: A small clinical study in children recently diagnosed with beta-thalassemia major shows that initiating zinc sulfate in addition to standard blood transfusions increases linear growth rate when compared with transfusions alone (87329). Another small clinical study in adult and pediatric patients with thalassemia major and low bone mass shows that taking zinc 25 mg daily (as zinc sulfate) for 18 months improves whole-body bone mineral content, as well as hip and spine bone mineral density, by small amounts when compared with placebo (90208).
• Brain tumor. It is unclear if dietary zinc is beneficial for reducing the risk for brain cancer. Details: Population research has found that zinc intake is not associated with a reduced risk of developing brain cancer (87098).
• Breast cancer. It is unclear if increased dietary zinc intake is beneficial for reducing the risk for breast cancer. Details: Population research has found that neither zinc intake nor blood levels of zinc are associated with a reduced risk of breast cancer (106229).
• Bronchiolitis. It is unclear if oral zinc is beneficial for viral bronchiolitis in infants and children. Details: A small clinical study in children 2 years or younger with acute viral bronchiolitis shows that taking elemental zinc 10-20 mg as zinc sulfate for 5 days improves clinical recovery and reduces the duration of hospital stay by almost one day when compared with placebo. After 72 hours, 98% of infants and children taking zinc were considered fully recovered, compared to only 52% of infants taking placebo (96076).
• Burning mouth syndrome. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with burning mouth syndrome shows that taking zinc 15 mg and vitamin C 35 mg once daily, along with a vitamin B complex twice daily, for 30 days modestly decreases pain and burning when compared to baseline (105195). The validity of this finding is limited by the lack of a comparator group. Furthermore, it is unclear if the benefit is due to zinc, other vitamins, or the combination.
• Burns. Intravenous zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. The effects of oral zinc for burn healing are unclear. Details: Administering zinc intravenously in combination with other minerals seems to improve the outcomes of burn patients. Supplementation with zinc, copper, and selenium appears to improve wound healing, reduce pulmonary infections, and shorten intensive care unit stay in patients with serious burns (6520,87085). The effect of supplementation with zinc alone is unclear.
• Canker sores. It is unclear if oral zinc is beneficial in patients with canker sores. Details: Evidence for the use of zinc in canker sores is conflicting. A small clinical crossover study in patients with recurrent canker sores shows that taking zinc sulfate 660 mg daily for 3 months does not improve the size or frequency of canker sore ulcers when compared with control (6592). However, another clinical study in patients with recurrent sores and low or normal zinc levels shows that taking zinc sulfate 220 mg daily for 1 month reduces recurrence of sores when compared with placebo (86964). Reasons for conflicting results are unclear. Zinc might be beneficial when used in a muco-adhesive formulation. A small clinical study in patients with canker sores shows that taking a muco-adhesive zinc sulfate 5 mg tablet three times daily for 7 days reduces pain and speeds up healing when compared with placebo (104048).
• Cataracts. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Taking zinc orally in combination with antioxidant vitamins does not seem to help treat or prevent cataracts. Taking elemental zinc 80 mg plus vitamin C 500 mg, vitamin E 400 IU, and beta-carotene 15 mg daily does not seem to have any effect on the development or progression of age-related lens opacities (cataracts) or the need for cataract surgery in well-nourished people 55-80 years of age. However, it is unknown whether earlier intervention and/or a longer period of treatment with supplements would have any effect on cataracts (7304).
• Chemotherapy-induced acral erythema. It is unclear if oral zinc reduces the severity of acral erythema induced in patients treated with the vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) treatment regorafenib. Details: A small study in patients with metastatic colorectal cancer undergoing treatment with regorafenib shows that taking zinc gluconate 78 mg twice daily reduces the proportion of patients with more severe acral erythema when compared with control. Though there is no association in the zinc treatment group, lower serum zinc levels seem to correlate with more severe acral erythema in the control group, suggesting a possible role of zinc deficiency in the pathogenesis of acral erythema (112472). The validity of this study is limited by the lack of blinding.
• Chemotherapy-related fatigue. It is unclear if oral zinc improves symptoms in patients with fatigue due to chemotherapy. Details: A small clinical study in patients undergoing 4 or more cycles of chemotherapy for colorectal cancer shows that taking zinc 70 mg daily for 16 weeks does not improve fatigue or quality of life when compared with placebo (97141).
• Chronic fatigue syndrome (CFS). Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in females with CFS shows that taking zinc 10 mg as zinc sulfate plus melatonin 1 mg daily for 16 weeks modestly reduces self-reported symptoms of physical fatigue when compared with placebo. However, there was no effect on cognitive or psychological symptoms, sleep, or symptoms of anxiety or depression (106241). This study may not have been adequately powered to detect differences between groups.
• Cirrhosis. It is unclear if zinc is beneficial for reducing cirrhosis-related mortality. Details: A meta-analysis of four small clinical trials shows that zinc supplementation does not seem to reduce mortality in patients with cirrhosis when compared with control (104054). This finding is limited due to the heterogeneity and small size of the available studies.
• Cognitive function. It is unclear if zinc is beneficial for cognitive function. Details: A very small clinical study in adults with overweight and obesity shows that taking supplemental zinc 30 mg daily for 12 weeks improves some measures of cognitive function and executive processing but does not improve verbal fluency when compared with placebo (112471). Zinc has also been evaluated in combination with other ingredients. A small clinical trial in healthy adults shows that taking a specific product containing a combination of zinc 9 mg, Lactobacillus helveticus, Lactiplantibacillus plantarum, Bifidobacterium longum, and other ingredients (Puraflor, GSK Consumer Healthcare, Milano, Italy) orally daily for 4 weeks does not affect cognitive performance during acute stress when compared with placebo (110923).
• Colorectal adenoma. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A large clinical study shows that taking a combination supplement containing zinc 30 mg, selenium 200 mcg (as l-selenomethionine), vitamin A 2 mg (as retinol), vitamin C 180 mg, and vitamin E 30 mg (as D-a-tocopherol acetate) by mouth daily for 5 years or until the recurrence of an adenoma reduces the risk of recurrent large-bowel adenomas by approximately 40% when compared with placebo (92903). It is not clear if the benefit is due to zinc, other supplements, or the combination.
• Colorectal cancer. It is unclear if oral zinc is beneficial for reducing colorectal cancer risk. Details: Population research has found that increased intake of zinc is associated with a 17% to 20% reduced risk of colorectal cancer (90213,90220).
• Congenital heart disease. It is unclear if oral zinc is beneficial for reducing the risk of congenital heart defects. Details: An observational study in pregnant adults has found that consuming the recommended nutritional intake of zinc may be associated with a lower risk of total congenital heart defects in infants, including atrial and ventricular septal defects, when compared with low zinc intake. This association appears to persist despite copper or selenium intake (108445).
• Critical illness (trauma). It is unclear if oral zinc is beneficial for critically ill patients. Details: A meta-analysis of two small randomized clinical trials in adults with head trauma shows that supplementing zinc, given as 120 mg elemental zinc orally daily or 12 mg elemental zinc intravenously daily for 15 days to 3 months, regardless of serum zinc levels, does not improve the risk of 30-day mortality when compared with control (111290). However, the study may have been inadequately powered to detect a difference between groups.
• Dementia. Although there is interest in using oral zinc for dementia, there is insufficient reliable information about the clinical effects of zinc for this condition.
• Diabetic foot ulcers. Although there is interest in using oral zinc for diabetic foot ulcers, there is insufficient reliable information about the clinical effects of zinc for this condition.
• Diabetic neuropathy. It is unclear if oral zinc is beneficial in patients with diabetic neuropathy. Details: A small clinical study in patients with poorly-controlled diabetic neuropathy shows that taking zinc sulfate 660 mg daily for 6 weeks improves motor nerve conduction velocity and reduces fasting and postprandial blood sugar when compared to baseline (86933). The validity of this finding is limited by the lack of statistical comparison to the control group.
• Down syndrome. It is unclear if oral zinc is beneficial for improving immune function in people with this condition. Details: A very small clinical study in Down syndrome patients with zinc deficiency shows that taking zinc sulfate 1 mg/kg daily for 2 months seems to improve immune function and reduce recurrent infections when compared with baseline (87289). The validity of this finding is limited by the lack of a control group. Another small clinical study in children with Down syndrome shows that zinc 25-50 mg daily for 6 months does not improve immune function when compared with placebo (87278). Reasons for the discrepancies may be related to the dose of zinc or zinc status at baseline.
• Dysmenorrhea. It is unclear if oral zinc is beneficial in patients with dysmenorrhea. Details: Preliminary clinical research in females aged 13 to 21 years with primary dysmenorrhea shows that taking zinc sulfate 40 mg orally daily for the first 3 days of menstruation for three cycles reduces mean pain scores by 51% when compared with placebo (111446).
• Epilepsy. There is limited evidence on the oral use of zinc in children with intractable seizures. Details: A small clinical study in children with intractable epilepsy shows that taking elemental zinc 1 mg/kg daily as zinc sulfate heptahydrate for 6 months reduces seizures when compared with placebo. About 31% of children taking zinc experienced a 50% decrease in seizure frequency, compared to only 5% of children taking placebo (96078).
• Esophageal cancer. It is unclear if oral zinc is beneficial for esophageal cancer prevention. Details: Population research in Chinese and Iranian patients has found that low intake of zinc is associated with an increased risk of esophageal squamous cell cancer (17205,87059). However, other population research in patients from America, Europe, or Asia has found that dietary zinc intake is not associated with esophageal cancer risk (90213).
• Fatigue. It is unclear if oral zinc is beneficial for reducing fatigue in older individuals. Details: A clinical study in adults 50 years and older, some with below-normal levels of zinc at baseline, shows that taking zinc 30 mg daily for 70 days improves subjective fatigue when compared with no intervention (105675). The validity of this finding is limited due to a lack of placebo control and potential performance bias. Additionally, it is unclear whether baseline zinc status alters the benefits of zinc supplementation.
• Fecal incontinence. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in females with fecal incontinence shows that topically applying an ointment containing zinc sulfate 1% and aluminum sulfate 5% to the anal canal mucosa three times daily for 4 weeks improves symptoms approximately twice as much as a placebo ointment. Quality of life related to the incontinence also improved (90219).
• Gastric cancer. It is unclear if dietary zinc is beneficial for gastric cancer prevention. Details: Population research has found that increased dietary zinc intake is not associated with a decreased risk of gastric cancer (90213).
• Head and neck cancer. It is unclear if oral zinc improves survival in patients with head and neck cancers. Details: Preliminary clinical research in patients with head and neck cancers shows that zinc supplementation does not improve disease-free or metastasis-free survival rates after 3 years when compared with placebo (87103).
• Hepatic encephalopathy. It is unclear if oral zinc is beneficial for reducing the severity of hepatic encephalopathy or preventing recurrence. Details: A meta-analysis of small clinical studies, as well as some individual clinical studies, show that short-term zinc supplementation improves cognitive function and possibly quality of life in patients with hepatic encephalopathy. These findings are based on results from the number connection test and other tests (87377,90202,106227). One study in patients with minimal hepatic encephalopathy used zinc bisglycinate 75 mg three times daily, providing elemental zinc 45 mg daily for 12 weeks (106227). However, other preliminary clinical research shows that short-term zinc supplementation does not improve hepatic encephalopathy severity when compared with placebo when assessed using Conn's index, which includes evaluation of mental state, asterixis (flapping tremor), number connection test, electroencephalogram (EEG) record, and plasma ammonia (87144). Also, a meta-analysis of clinical research shows that zinc sulfate supplementation does not reduce encephalopathy recurrence (90202). Based on these results, zinc supplementation may marginally improve cognitive function in hepatic encephalopathy patients, but it does not appear to improve disease severity or reduce the risk of recurrence.
• HIV/AIDS-related diarrhea. It is unclear if oral zinc is beneficial for preventing diarrhea in adult HIV patients. Details: Short-term zinc supplementation does not appear to TREAT diarrhea in adult HIV patients with persistent diarrhea. Clinical research shows that taking zinc 50 mg twice daily for 7 days does not reduce the duration of HIV-related diarrhea when compared with placebo (87055). However, zinc supplementation may help PREVENT HIV-related diarrhea when administered long-term. Clinical research shows that taking elemental zinc 12-15 mg daily for 18 months reduces the rate of diarrhea by about half when compared with placebo in adult HIV patients with zinc deficiency (87216). In HIV-infected children, clinical research shows that taking elemental zinc 10 mg daily for 6 months can reduce the occurrence of diarrhea by 49% when compared with placebo (82377). However, administering zinc in combination with vitamin A until 2 years of age does not reduce the occurrence of diarrhea when compared with vitamin A alone in HIV-infected children (82417).
• HIV/AIDS-related opportunistic infections. It is unclear if oral zinc is beneficial in opportunistic infections in patients with HIV/AIDs. Details: A small clinical study in patients with AIDS shows that taking zinc supplements orally in combination with zidovudine (AZT, Retrovir) might reduce opportunistic infections of Pneumocystis carinii and Candida when compared with taking zidovudine without zinc (6566).
• Human papillomavirus (HPV). It is unclear if oral zinc is beneficial for preventing relapse in patients with vulvar warts or for treating HPV infections and cervical lesions in patients with abnormal cervical cytology. Details: One small clinical study in patients with vulvar warts shows that taking zinc sulfate 400 mg daily for 8 weeks in addition to topical treatments including podophyllin 20%, imiquimod 5%, or cryotherapy, does not affect the duration of response, but does reduce the relapse rate by approximately 66% after 6 months, when compared with topical treatments alone (90190). Additionally, a small, open-label study in zinc-sufficient females with HPV shows that taking zinc sulfate 220 mg twice daily for 3 months reduces the odds of persistent HPV infection by 87% and improves the resolution of pre-existing cervical lesions when compared with no treatment (109456).
• Hypertension. It is unclear if oral zinc reduces blood pressure in normotensive or hypertensive patients. Details: A meta-analysis of small clinical trials shows that taking zinc reduces systolic blood pressure by about 1.5 mmHg, but does not reduce diastolic blood pressure, when compared with placebo. Response did not differ with the dosage of zinc or duration of supplementation. Only one study evaluated patients with hypertension; other patient populations included those with type 2 diabetes, diabetic retinopathy, pre-diabetes, obesity, polycystic ovary syndrome (PCOS), and patients on dialysis (104052). More research in patients with hypertension is needed to determine if zinc is beneficial in this population.
• Impaired glucose tolerance (prediabetes). While some conflicting evidence exists, several small clinical studies suggest that oral zinc may improve glycemic control in patients with prediabetes. Details: A meta-analysis of three low-quality studies in patients with prediabetes suggests that taking zinc sulfate 20-30 mg, alone or in combination with lysine and vitamin C, for 6-12 months reduces fasting blood glucose and postprandial glucose when compared with control (105682). Furthermore, a small clinical study in patients with prediabetes shows that taking zinc gluconate 30 mg daily for 90 days improves glycemic parameters when compared with placebo. All study participants were also instructed to increase physical activity and start a calorie-restricted diet (105391). However, another small clinical study in patients with prediabetes shows that taking zinc gluconate 30 mg daily for 12 months does not improve glycemic parameters when compared with placebo (109454). The available research has been conducted in Sri Lanka, Bangladesh, Iran, and Australia; it is unclear if these findings are generalizable to other geographic locations.
• Intestinal parasite infection. It is unclear if oral zinc is beneficial in patients with intestinal parasitic infections. Details: Zinc supplementation may help TREAT infection from Schistosoma mansoniin, but not other parasites, in children in developing countries. Results from one clinical study show that taking oral zinc sulfate 30-50 mg for 12 months reduces the intensity of Schistosoma mansoniin infection in children, as measured by number of eggs per gram in feces, when compared with placebo (87495). However, supplementation with zinc does not appear to reduce the intensity of Ascaris lumbricoides, Trichiuris trichura, nor Giardia lamblia infection in children (6586). Furthermore, preliminary clinical research suggests that supplementation with zinc may increase the duration of Entamoeba histolytica infection in children (87099). There are also inconsistent results regarding the effects of zinc in PREVENTING intestinal parasite infections. Some clinical research shows that taking zinc in combination with vitamin A reduces the incidence of Giardia lamblia infections when compared with placebo (87099). However, zinc supplementation does not appear to prevent intestinal infections by Ascaris lumbricoides, Schistosoma haematobium, nor Schistosoma mansoniin (87099,87495).
• Kidney failure. It is unclear if oral zinc is beneficial for patients on hemodialysis who have resistance to erythropoiesis-stimulating agents (ESAs). Details: Zinc deficiency is thought to play a role in ESA-resistant anemia in patients with kidney failure. A small clinical trial in patients on hemodialysis with low zinc levels shows that taking zinc acetate hydrate, usually 25mg or 50 mg daily, for 12 months increases plasma levels of zinc and modestly reduces the required weekly dose of ESAs when compared with placebo. However, there was no effect on hemoglobin levels (109781).
• Leukemia. It is unclear if oral zinc is beneficial for improving weight maintenance in children and adolescents with leukemia. Details: A small clinical study in children and adolescents with acute leukemia shows that taking zinc 2 mg/kg (as an amino acid salt) in two divided doses daily for 60 days doubles weight gain and reduces infection rate by approximately 60% when compared with placebo. However, zinc supplementation does not appear to improve nutritional status (90204).
• Liver cancer. It is unclear if oral zinc is beneficial for preventing hepatocellular carcinoma (HCC). Details: In patients treated for hepatitis C, the presence of hepatic fibrosis increases the risk for development of HCC, and is also associated with low plasma zinc levels. In a retrospective analysis of patients with a sustained virological response to hepatitis C therapy, those taking oral zinc supplements for at least 6 months had approximately half the risk of developing HCC when compared with those not taking zinc. Maintaining a serum zinc level above 90 mcg/dL seems to reduce the risk for HCC (106904).
• Lung cancer. It is unclear if increased dietary zinc intake is beneficial for reducing the risk of lung cancer. Details: Population research suggests that the highest dietary intake of zinc is associated with a 32% reduced risk of lung cancer when compared with the lowest intake (106235). Additionally, another large epidemiological cancer screening trial with a mean follow-up of 12.2 years suggests that dietary intake of zinc is protective against lung cancer, with the highest quartile of dietary intake showing the greatest benefit. However, this protective effect was not found for supplemental intake of zinc (112096).
• Male infertility. It is unclear if oral zinc is beneficial for infertility in males. Details: Some preliminary clinical research shows that taking zinc sulfate 66 mg daily increases sperm count, testosterone levels, and the incidence of pregnancy in idiopathic infertile men with low testosterone levels (9334,87430). Another clinical study shows that taking zinc sulfate 66 mg daily can improve sperm morphology by approximately 33% when compared to baseline in men with a grade III varicocele (90194). However, not all research agrees. One clinical study shows that taking elemental zinc 30 mg with folic acid 5 mg daily for 6 months does not improve sperm morphology or pregnancy rates when compared with placebo in infertile men (102085). It is possible the lower dose used in this study was insufficient to produce the beneficial effects observed in earlier research. Zinc supplementation has also been studied as part of combination therapy. A retrospective study in males with or without varicocele-related infertility has found that taking a specific combination product containing zinc 10 mg, L-carnitine fumarate 1725 mg, acetyl-L-carnitine 500 mg, vitamin C 90 mg, coenzyme Q10 20 mg, folic acid 0.2 mg, selenium 0.05 mg, and vitamin B12 0.015 mg (Proxeed Plus, Sigma-Tau) orally twice daily for 6 months improves sperm count, sperm concentration, and sperm motility when compared with baseline. Improvements in semen parameters were greatest in subjects with more severe varicoceles. The validity of this study is limited by the lack of a comparator group (111296). There is also interest in using zinc to improve results of in vitro fertilization (IVF). A small clinical study in couples undergoing IVF suggests that infertile male partners who take a specific combination product (Menevit) containing zinc and other antioxidants seem to have an increased rate of viable pregnancies when compared with placebo (87087). However, it's unclear if the benefit can be attributed to zinc, other antioxidants, or the combination.
• Melasma. It is unclear if topical zinc reduces melasma severity. Details: A small clinical study shows that applying a topical solution containing zinc sulfate 10% once daily for 2 months is less effective at reducing melasma severity when compared with hydroquinone 4% (90232).
• Menopausal symptoms. It is unclear if oral zinc improves sexual function after menopause. Details: A single clinical trial shows that taking zinc sulfate 110 mg daily for 6 weeks modestly improves testosterone levels and sexual function, including desire, arousal, satisfaction, and pain, after menopause when compared with placebo (106228).
• Migraine headache. It is unclear if oral zinc is beneficial in patients with migraine. Details: Two small clinical studies in patients with migraine show that taking zinc sulfate 200 mg or zinc gluconate 15 mg daily for 8-12 weeks modestly reduces migraine severity and frequency when compared with placebo (104040,105684). Both studies were conducted in Iran; it is unclear if these findings are generalizable to other geographic locations.
• Nasopharyngeal cancer. It is unclear if oral zinc is beneficial in patients with this type of cancer. Details: A small clinical study in patients with locally advanced nasopharyngeal cancer shows that zinc supplementation 75 mg daily for 2 months may improve disease-free survival rates after 5 years when compared with placebo (87163).
• Neonatal jaundice. It is unclear if oral zinc is beneficial for neonatal jaundice. Details: Two small clinical studies in infants with idiopathic neonatal hyperbilirubinemia show that receiving oral zinc sulfate 5 mg twice daily for 5-7 days does not affect levels of total bilirubin, the required duration of phototherapy, or the duration of hospitalization, when compared with placebo (90212,104814). A larger clinical trial suggests that this lack of effect may be due to the need for a longer treatment duration. In preterm infants receiving phototherapy and zinc 1.2 mg/kg daily as zinc sulfate heptahydrate, via either orogastric or nasogastric tube for 10 days, serum bilirubin levels were modestly decreased only on days 8-10 when compared with phototherapy alone (106242).
• Nonalcoholic fatty liver disease (NAFLD). It is unclear if oral zinc is beneficial in patients with NAFLD. Details: A small clinical study in patients with NAFLD shows that following a calorie-restricted diet and taking zinc 30 mg daily for 12 weeks reduces certain liver enzymes, but does not improve steatosis or reduce weight, when compared with taking placebo and following a calorie-restricted diet (104046).
• Non-Hodgkin lymphoma. It is unclear if oral zinc is beneficial for non-Hodgkin lymphoma prevention. Details: Population research has found that higher dietary intake of zinc is associated with a 42% decreased odds of developing non-Hodgkin lymphoma (87048).
• Obesity. Small studies suggest that oral zinc does not reduce weight or calorie intake in people with overweight or obesity. Details: A very small clinical study in adults with overweight or obesity shows that taking supplemental zinc 30 mg daily for 12 weeks does not reduce body weight, body mass index (BMI), calorie intake, or macronutrient intake when compared with placebo (112471). Additionally, clinical research in adults with overweight or obesity shows that taking zinc gluconate 25 mg and L-selenomethionine 200 mcg once daily for 8 weeks does not improve BMI, total body fat, or fat free mass when compared with placebo (111448).
• Obsessive-compulsive disorder (OCD). It is unclear if oral zinc reduces symptoms in patients with OCD. Details: A small clinical study in patients with OCD shows that taking zinc sulfate 200 mg twice daily with fluoxetine 20 mg daily for 8 weeks modestly reduces the severity of OCD symptoms when compared with taking placebo with fluoxetine (90223).
• Oral mucositis. It is unclear if oral or topical zinc prevents oral mucositis due to chemotherapy. Some small clinical studies suggest that oral zinc might prevent mucositis due to radiotherapy. Details: Two small clinical studies in adults with leukemia and other cancers shows that taking zinc sulfate 220 mg three times daily for 14 days or until the end of chemotherapy treatment reduces oral mucositis and pain intensity when compared with placebo (90191,98132). However, smaller doses have not shown benefit. A small clinical study in children and adolescents with leukemia shows that taking zinc 2 mg/kg daily (up to 60 mg daily) in two divided doses does not affect chemotherapy-induced mucositis when compared with placebo (90204). An unblinded clinical study in children and adolescents aged 8-16 years with recently diagnosed leukemia shows that taking zinc gluconate 50 mg (7 mg elemental zinc) daily does not significantly reduce the incidence or duration of oral mucositis when compared with a control group not receiving zinc (104816). Zinc also doesn't seem to be beneficial with high-dose chemotherapy. A small clinical study in adolescents and adults receiving high-dose chemotherapy prior to undergoing hematopoietic stem cell transplantation (HSCT) suggests that taking zinc sulfate 220 mg (50 mg elemental zinc) twice daily, beginning one day prior to the chemotherapy regimen and continuing for 3 weeks, does not affect the severity, duration, or onset of mucositis when compared with placebo (90215). Other preliminary clinical research in children aged 3-18 years receiving chemotherapy for leukemia or other cancer also shows that taking zinc 1 mg/kg orally daily for 14 days, beginning on the first day of chemotherapy, does not reduce the incidence or severity of mucositis when compared with placebo (111447). Topical zinc has also been investigated for radiation-induced or chemotherapy-induced oral mucositis. In two clinical studies, using 7.5 mL of a mouthwash containing zinc chloride 0.2% twice for 2 minutes every 8 hours for 3 weeks modestly reduces the incidence and severity of oral mucositis, and improves quality of life, when compared with a placebo mouthwash (106232,109690). In one study, the average patient weight was higher in the group using the mouthwash containing zinc (106232). Other preliminary clinical research in adults with head and neck cancer undergoing radiotherapy treatment, consisting of at least 30 Gy radiation exposure shows that using zinc sulfate 1% mouthwash, 5 mL three times daily for 6 weeks, beginning on the first day of radiation therapy, moderately improves oral mucositis severity and pain scores when compared with chlorhexidine 0.2% or placebo mouthwash (111291). Taking zinc orally might be beneficial in radiation-induced oral mucositis. A small clinical study in patients with head and neck tumors shows that taking zinc sulfate, providing 150 mg elemental zinc, daily starting at the first day of radiation therapy and ending at 6 weeks, reduces the severity of mucositis and prolongs the onset of mucositis when compared with placebo (86981). Another clinical study in patients with head and neck cancer shows that taking zinc sulfate 150 mg daily during and after chemoradiotherapy treatment, consisting of a total 69.5 Gy radiation exposure and cisplatin 40 mg/m2 weekly, is associated with less severe mucositis when compared with placebo (105677).
• Osteoporosis. It is unclear if oral zinc improves bone density in patients with osteoporosis. Details: Population research has found that reduced zinc intake and lower zinc serum levels seem to be associated with lower bone mineral density (BMD) (6920,14410). In elderly patients with at least marginal zinc deficiency who are taking standard therapy for osteoporosis, preliminary clinical research shows that taking zinc acetate dihydrate (Nobelzin, Nobelpharma) providing elemental zinc 25 mg twice daily for 12 months increases BMD when compared with baseline. Increases in serum zinc were associated with improvements in BMD. However, it is unclear if increases in BMD were significant when compared with placebo (106230). It is also unclear if zinc improves BMD in patients without zinc deficiency. A small clinical study in healthy postmenopausal adults suggests that taking zinc in combination with copper, manganese, and calcium might slow bone loss when compared with placebo (1994). It is not clear if this effect is due to zinc, other ingredients, or the combination.
• Overall mortality. It is unclear if oral zinc reduces overall mortality in young children. Details: A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc in daily doses of at least 10 mg reduces the risk of all-cause mortality by 16% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation. The risk of mortality was reduced by 54% when children took zinc for up to one year, but overall mortality was not reduced in studies lasting at least one year (106239).
• Periodontitis. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with moderate or advanced periodontitis shows that taking a combination supplement containing zinc 3.75 mg, alpha-lipoic acid, coenzyme Q10, cranberry extract, grapeseed extract, selenium, vitamin C, and vitamin E twice daily for 8 weeks in addition to standard nonsurgical therapy does not reduce periodontal indices including bleeding on probing, gingival recession, plaque index, or inflammation when compared with placebo (111708).
• Polycystic ovary syndrome (PCOS). It is unclear if oral zinc is beneficial in patients with PCOS. Details: A small clinical study in adults taking metformin for PCOS shows that also taking zinc sulfate 220 mg (50 mg elemental zinc) daily for 8 weeks improves hair loss and facial growth, but not acne, when compared with placebo (96071).
• Postoperative sore throat. It is unclear if oral zinc is beneficial for postoperative sore throat. Details: Clinical research shows that dissolving a lozenge containing zinc 40 mg as zinc sulfate in the mouth in the 30 minutes before surgery involving endotracheal intubation reduces the incidence of postoperative sore throat by 58% when compared with placebo lozenges. It also seems to reduce the severity of postoperative sore throat that does occur (97138). Other clinical research in adults undergoing a procedure that required endotracheal intubation shows that using a preoperative 30-mL gargle containing zinc 40 mg does not affect sore throat scores when compared with magnesium sulphate 250 mg or budesonide 200 mcg gargles (114763).
• Postpartum depression. It is unclear if oral zinc prevents postpartum depression after a Cesarean section (C-section). Details: A small observational study in pregnant patients with anemia who underwent C-section has found that taking zinc sulfate 100 mg daily for 4 days after surgery is associated with a 75% reduction in the odds of developing postpartum depression when compared with no supplementation (109452).
• Premenstrual syndrome (PMS). It is unclear if oral zinc improves symptoms in patients with PMS. Details: A small clinical study in female college students shows that taking elemental zinc 30 mg daily for 3 months improves quality of life, but not quality of sleep, when compared with placebo (104049).
• Preterm labor. It is unclear if oral zinc reduces the risk of preterm labor. Details: Observational research has found that low dietary intake of zinc during pregnancy is associated with an increased likelihood of preterm deliveries (87471). Also, most meta-analyses of clinical research show that taking zinc supplements during pregnancy modestly reduces the risk of preterm birth (106231). However, one large meta-analysis of 22 clinical studies shows that zinc supplementation during pregnancy seems to have little or no benefit for reducing the risk of preterm birth when compared with control (105679). Zinc supplementation also does not seem to reduce the risk of stillbirth, neonatal death, spontaneous abortion, or premature rupture of membranes (97142,105679,106231).
• Prostatitis. It is unclear if oral zinc improves symptoms in men with chronic prostatitis. Details: A clinical study in men with chronic prostatitis shows that taking zinc sulfate 220 mg daily along with prazosin 2 mg daily for 12 weeks does not improve difficulty urinating or quality of life, but does seem to improve pain, when compared with prazosin alone (90210). The validity of this study was limited by a significant dropout rate.
• Pruritus. There is limited evidence on the oral use of zinc for reducing pruritis in hemodialysis patients. Details: A small clinical study in end-stage renal disease patients with hemodialysis-associated pruritus shows that taking zinc sulfate 220 mg twice daily for 2 months reduces pruritus severity when compared with placebo (90218).
• Psoriatic arthritis. It is unclear if oral zinc improves psoriatic arthritis symptoms. Details: Two small clinical trials in patients with psoriatic arthritis show that taking zinc orally, alone or in combination with nonsteroidal anti-inflammatory drugs (NSAIDs), does not seem to reduce pain or improve function when compared with control (6514,6515).
• Respiratory tract infections. It is unclear if oral zinc reduces respiratory tract infections in children. Details: An open-label study in children aged 6 months to 5 years with zinc deficiency shows that taking zinc sulfate 20 mg orally once daily for 2 weeks reduces the number of episodes and the mean duration of upper and lower respiratory tract infections over 6 months of follow-up when compared with the 6 months prior to zinc supplementation (104815). The validity of this finding is limited by the lack of a comparator group.
• Rosacea. It is unclear of oral zinc improves symptoms of rosacea or quality of life. Details: A small clinical trial shows that taking zinc sulfate 440 mg in two divided doses daily for 90 days does not improve quality of life or symptoms associated with rosacea when compared with placebo (90195).
• Seizures. It is unclear if oral zinc reduces recurrent febrile seizures in children. Details: Although some individual preliminary clinical research disagrees (96069), a meta-analysis of generally low-quality research in children under 5 years of age with a previous febrile seizure shows that taking zinc sulfate 1-2 mg/kg or 20 mg daily for 6-12 months does not reduce febrile seizure recurrence when compared with placebo (106237). Also, a small clinical study shows that taking zinc does not increase the time to first febrile seizure recurrence (96069).
• Sepsis. It is unclear if oral zinc is beneficial in sepsis of the newborn. Details: A meta-analysis of clinical research in children under the age of five years shows that supplementation with zinc reduces the risk of sepsis mortality by 57% when compared with either placebo, other vitamin and/or mineral supplementation, or no supplementation (106239). Also, a small clinical study in newborns with sepsis shows that giving zinc sulfate monohydrate 3 mg/kg twice daily for 10 days along with antibiotics reduces the likelihood of neurological abnormalities, such as those related to posture, behavior, and reflexes, by 70% when compared with antibiotics alone. Mortality and length of hospital stay were not improved, but the study may have been inadequately powered to detect a difference in these parameters (96077). Another study in preterm infants with late-onset sepsis (developing at least 72 hours after birth), shows that giving 1.4 mg/kg elemental zinc daily orally for 10 days in addition to antibiotics reduces the number of infants with unresolved sepsis at 10 days, and reduces C-reactive protein and procalcitonin levels, when compared with giving antibiotics alone (104819). A meta-analysis of small clinical studies in infants less than 4 months old shows that administering zinc 1-3 mg/kg daily for 1-18 weeks may reduce the rate of infant mortality and treatment failure when compared with placebo or control, but does not seem to prevent sepsis or improve sepsis-related mortality (108444).
• Shigellosis. It is unclear if oral zinc is beneficial in patients with acute shigellosis from food poisoning. Details: A small clinical study in malnourished children with acute shigellosis (food poisoning) shows that administering a multivitamin syrup containing elemental zinc 20 mg daily for 2 weeks, in addition to standard treatment, can improve recovery time and reduce the number of diarrhea episodes when compared with multivitamin syrup without elemental zinc (87088).
• Sleep deprivation. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in sleep-deprived recreational athletes shows that taking a combination of zinc 90 mg, magnesium 1350 mg, and vitamin B6 31.5 mg orally for 3 nights at bedtime does not change sleep quality, subjective sleepiness, mood, or fatigue when compared with placebo (113655).
• Substance use disorder. It is unclear if oral zinc is beneficial for substance use disorder. Details: Preliminary clinical research in adults with opioid use disorder that were being treated with methadone shows that taking zinc sulfate, containing 12 mg zinc, orally daily for 3 months moderately improves relapse prevention scores, including drug use and drug craving scores, when compared with control. Taking zinc also modestly improved stress and anxiety scores (111293).
• Traumatic brain injury (TBI). There is limited evidence on the parenteral use of zinc for closed head injury. Details: A small clinical study shows that administering zinc parenterally immediately following severe closed head injury seems to improve the rate of neurological recovery when compared with standard therapy (2696).
• Tuberculosis. It is unclear if oral zinc can improve outcomes in patients receiving tuberculosis treatment. Details: Low levels of zinc are common in patients with tuberculosis. In patients newly diagnosed with tuberculosis and using anti-tuberculosis treatment, some clinical research shows that taking zinc 50 mg daily as zinc sulfate for 6 months increases the number of patients with negative sputum smears by 50% to 80% within the first 6 weeks of treatment when compared with placebo. However, there were no differences in the number of patients with negative smears after this time point. There were also improvements in some liver function enzyme levels after 2 months, but not 6 months, when compared with placebo (106238). However, other clinical research shows that taking zinc 15-90 mg daily for 2-6 months does not improve cure rates or sputum smear conversions when compared with placebo. However, when combined with vitamin A, serum levels of vitamin A, zinc, and hemoglobin were modestly improved and there was a modest increase in sputum smear conversions (109754).
• Urinary tract infections (UTIs). It is unclear if oral zinc is beneficial in children with UTI. Details: A low-quality, clinical study in children aged 3-12 years hospitalized for a UTI and receiving intravenous antibiotic treatment shows that taking zinc 1 mg/kg daily for 14 days reduces the duration of dysuria, urinary frequency, and urgency when compared with intravenous antibiotics alone. Zinc does not improve fever or the time to negative urine culture (96081). However, this study did not demonstrate that treatment groups were equal at baseline.
• Venous leg ulcers. It is unclear if oral or topical zinc is beneficial for leg ulcer healing. Details: Two small studies in elderly patients with leg ulcers suggest that using a zinc saline solution on a wound dressing or applying zinc oxide to a dressing might improve healing of leg ulcers (2694,6901). However, oral zinc supplementation does not seem to be beneficial. A meta-analysis of four small clinical trials in patients with venous leg ulcers shows that taking zinc orally does not improve healing when compared with placebo (104079).
• Vertigo. Oral zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research in adults with benign paroxysmal positional vertigo with serum 25-hydroxyvitamin D levels less than 20 ng/mL shows that taking a specific combination product containing zinc 7.5 mg, alpha-lipoic acid 600 mg, L-carnosine 165 mg, curcumin 100 mg, piperine 1 mg, cholecalciferol 800 units, vitamin B2 0.8 mg, and vitamin B6 1 mg (Vertistop D, Difass) orally daily for 6 months moderately reduces the number of vertigo relapse episodes when compared with control. However, in patients with serum 25-hydroxyvitamin D levels greater than 20 ng/mL that took a specific combination product containing zinc 7.5 mg, alanine 600 mg, L-carnosine 165 mg, curcumin 100 mg and piperine 1 mg (Vertistop L, Difass) orally daily for 6 months there was no difference in relapse episodes when compared with control (111294). It is unclear if this effect is due to zinc, other ingredients, or the combination.
• Water warts. It is unclear if oral zinc is beneficial for the treatment of water warts in children. Details: In children with water warts, preliminary clinical research shows that taking zinc sulfate heptahydrate (as Zinco syrup) for 2 months results in lesion resolution in 70% of patients when compared with baseline. Lesion resolution occurred in an additional 13% of patients in the month after treatment completion, with no recurrence in any of these children over the next 9 months. Zinc 3 mg daily was used in children up to 3 years of age, and 5 mg daily was used in older children (106234). Due to the lack of a comparator group, it is unclear if these outcomes are due to zinc or the natural resolution of the condition.
• Wound healing. Topical zinc might be beneficial for the healing of uncomplicated wounds. Details: A small clinical study shows that applying zinc chloride solution, standardized to contain zinc 20 mcg/mL, twice daily improves wound healing when compared with saline solution in patients with uncomplicated, skin wounds. However, when zinc is administered as a component of an insulin product (Humulin, Eli Lilly and Company), it seems to be more effective than zinc chloride alone (90192).
• Wrinkled skin. Topical zinc has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A topical preparation containing 10% vitamin C as L-ascorbic acid and acetyl tyrosine, zinc sulfate, sodium hyaluronate, and bioflavonoids (Cellex-C High Potency Serum) applied to photo-aged facial skin for 3 months seems to improve fine and coarse wrinkling, yellowing and sallowness, roughness, and skin tone when compared with placebo (6155). More evidence is needed to rate zinc for these uses.

(Read more about ZINC)

LIKELY SAFE ...when used orally and appropriately. Drinking decaffeinated coffee or coffee containing caffeine in low to moderate amounts is safe (15,98806). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, drinking up to 4 cups of coffee daily providing caffeine 400 mg daily is not associated with significant adverse cardiovascular, bone, behavioral, or reproductive effects in healthy adults (11733,98806). The US Dietary Guidelines Advisory Committee states that there is strong and consistent evidence that consumption of beverages such as coffee that contain caffeine 400 mg daily is not associated with increased risk of major chronic diseases, such as cardiovascular disease or cancer, in healthy adults (98806).

POSSIBLY UNSAFE ...when used orally in excessive amounts. Acute use of high doses of caffeine (more than 400 mg per day), which is found in more than 4 cups of caffeinated coffee, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Drinking caffeinated coffee in amounts greater than 6 cups per day (about 600 mg caffeine) short-term or long-term can also cause caffeinism, with symptoms of anxiety possibly progressing to delirium and agitation. Chronic use of caffeine, especially in large amounts, can sometimes produce tolerance, habituation, and psychological dependence (3719). Abrupt discontinuance of caffeine can cause physical withdrawal symptoms (11733). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as coffee, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product. ...when used rectally as an enema. Coffee enemas have been linked to cases of severe electrolyte abnormalities and septicemia leading to severe side effects including death (3026,3347,3349,6652).

CHILDREN: POSSIBLY SAFE
when coffee containing caffeine is consumed orally in moderate amounts. Oral intake of caffeine in doses of less than 2.5 mg/kg daily is not associated with significant adverse effects in children and adolescents (11733,98806). However, higher doses should be avoided. The adverse effects typically associated with caffeine-containing coffee are usually more severe in children than adults (11733).

PREGNANCY: POSSIBLY SAFE
when used orally in moderate amounts. Intake of caffeine from coffee and other sources should be monitored during pregnancy. Caffeine crosses the human placenta, but is not considered a teratogen. Fetal blood and tissue levels are similar to maternal concentrations (4260). The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects (2708,2709,2710,2711,9606,11733,16014,16015). However, some research has also found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years (109846). In some studies, consuming amounts over 200 mg daily has been associated with a significantly increased risk of miscarriage (16014). This increased risk may be most likely to occur in people with genotypes that confer a slow rate of caffeine metabolism (98806). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, most healthy pregnant patients can safely consume caffeine in doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). Advise patients to keep caffeine consumption below 300 mg daily during pregnancy. This is similar to the amount of caffeine in about 3 cups of coffee. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine found in ingredients such as coffee, which naturally contains caffeine, does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

PREGNANCY: POSSIBLY UNSAFE
when caffeinated coffee providing more than 300 mg of caffeine daily is consumed orally. Caffeine from coffee crosses the placenta, producing fetal blood concentrations similar to maternal levels (4260). Consumption of caffeine in amounts over 300 mg daily is associated with a significantly increased risk of miscarriage in some studies (16014,98806). Advise patients to keep caffeine consumption from all sources below 300 mg daily during pregnancy. This is similar to the amount of caffeine in about 3 cups of coffee. High doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants (9891). High doses of caffeine have also been associated with spontaneous abortion, premature delivery, and low birth weight (2709,2711). Drinking more than 6 cups of coffee daily increases the risk of spontaneous abortion (2709). Drinking 8 or more cups of coffee daily doubles the risk of stillbirth when compared with those who do not drink coffee during pregnancy (10621).

LACTATION: POSSIBLY SAFE
when used orally. Drinking one or two caffeine-containing beverages daily during lactation is not associated with unacceptable levels of caffeine in human milk (11734).

LACTATION: POSSIBLY UNSAFE
when used orally in large amounts. Caffeine from coffee can cause wakefulness or irritability in breast-fed infants. Caffeine can also cause feeding intolerance and gastrointestinal irritation in infants (6026).

(Read more about COFFEE)

LIKELY SAFE ...when used orally and appropriately in food amounts (4960,4969,5792,5797). Oat bran has Generally Recognized as Safe (GRAS) status in the US (4912). Whole grain oats 50-100 grams daily have been used for up to 1 year without serious adverse effects (97520).

POSSIBLY SAFE ...when used topically and appropriately (12). Lotion containing colloidal oat 1% has been used topically without adverse effects for up to 6 weeks (97518,103340). There is insufficient reliable information available about the safety of oats when used orally in medicinal amounts.

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in food amounts (5792,5797).

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LIKELY SAFE ...when used orally as a flavoring in foods. The US Food and Drug Administration (FDA) lists passion flower as a permitted food flavoring additive, to be used in the minimum quantity necessary (91203).

POSSIBLY SAFE ...when used orally and appropriately in medicinal amounts, short-term. Passion flower extract has been used with apparent safety at doses up to 800 mg daily for up to 8 weeks (88198,102866). A specific passion flower extract (Pasipay, Iran Darouk Pharmaceutical Company) has been safely used at a dose of 45 drops daily for up to one month (8007,95036). Also, a tea prepared by steeping 2 grams of the dried aerial parts of passion flower in 250 mL of boiling water for 10 minutes has been used nightly for 7 nights (17374). There is insufficient reliable information available about the safety of passion flower when used topically.

CHILDREN: POSSIBLY SAFE
when used orally and appropriately, short-term. A specific passion flower product (Pasipay, Iran Darouk Pharmaceutical Company) has been used safely in children aged 6-13 years at a dose of 0.04 mg/ kg daily for 8 weeks (88197).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Some case reports suggest that passion flower use during the first and second trimesters of pregnancy may be associated with an increased risk for premature rupture of membranes and meconium aspiration syndrome; however, causality has not been confirmed (97279). The alkaloids harman and harmaline, which are sometimes found in passion flower, have been reported to have uterine stimulant activity (4,11020,95037). It is not known whether these constituents are present in sufficient quantities to have an effect.

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about PASSION FLOWER)

LIKELY SAFE ...when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 40 mg daily (7135). ...when used topically and appropriately (2688,6538,6539,7135,8623,11051,111291).

POSSIBLY SAFE ...when used orally and appropriately in doses higher than the tolerable upper intake level (UL). Because the UL of zinc is based on regular daily intake, short-term excursions above 40 mg daily are not likely to be harmful. In fact, there is some evidence that doses of elemental zinc as high as 80 mg daily in combination with copper 2 mg can be used safely for approximately 6 years without significant adverse effects (7303,8622,92212). However, there is some concern that doses higher than the UL of 40 mg daily might decrease copper absorption and result in anemia (7135).

POSSIBLY UNSAFE ...when used intranasally. Case reports and animal research suggest that intranasal zinc might cause permanent anosmia or loss of sense of smell (11155,11156,11703,11704,11705,11706,11707,16800,16801,17083). Several hundred reports of anosmia have been submitted to the US Food and Drug Administration (FDA) and the manufacturer of some intranasal zinc products (Zicam) (16800,16801). Advise patients not to use intranasal zinc products.

LIKELY UNSAFE ...when taken orally in excessive amounts. Ingestion of 10-30 grams of zinc sulfate can be lethal in adults (7135). Chronic intake of 450-1600 mg daily can cause multiple forms of anemia, copper deficiency, and myeloneuropathies (7135,17092,17093,112473). This has been reported with use of zinc-containing denture adhesives in amounts exceeding the labeled directions, such as several times a day for several years (17092,17093). Advise patients to follow the label directions on denture adhesives that contain zinc.

CHILDREN: LIKELY SAFE
when used orally and appropriately (7135). Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL). The UL for children is based on age: 4 mg daily for 0-6 months, 5 mg daily for 7-12 months, 7 mg daily for 1-3 years, 12 mg daily for 4-8 years, 23 mg daily for 9-13 years, and 34 mg daily for 14-18 years (7135,97140).

CHILDREN: POSSIBLY UNSAFE
when used orally in high doses. Taking amounts greater than the UL can cause sideroblastic anemia and copper deficiency (7135). ...when used topically on damaged skin. An infant treated with 10% zinc oxide ointment for severe diaper rash with perianal erosions developed hyperzincemia. Absorption seemed to occur mainly via the erosions; plasma levels dropped after the erosions healed despite continued use of the ointment (106905).

PREGNANCY: LIKELY SAFE
when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 34 mg daily during pregnancy in those 14-18 years of age and 40 mg daily in those 19-50 years of age (7135).

PREGNANCY: LIKELY UNSAFE
when used orally in doses exceeding the UL (7135).

LACTATION: LIKELY SAFE
when used orally and appropriately. Zinc is safe in amounts that do not exceed the tolerable upper intake level (UL) of 34 mg daily during lactation in those 14-18 years of age, and 40 mg daily for those 19-50 years of age (7135).

LACTATION: POSSIBLY UNSAFE
when used orally in doses exceeding the UL. Higher doses can cause zinc-induced copper deficiency in nursing infants (7135).

(Read more about ZINC)

ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Coffee contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level (38172). However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). It is recommended that methylxanthines such as caffeine, as well as methylxanthine-containing products, be stopped 24 hours prior to pharmacological stress tests (11770). However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

ALCOHOL (Ethanol) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, alcohol might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of alcohol and caffeine can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism (6370,24693).

ALENDRONATE (Fosamax) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Coffee reduces alendronate bioavailability.  Details Separate coffee ingestion and alendronate administration by two hours. Coffee reduces alendronate bioavailability by 60% (11735).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Unlikely •  Level of Evidence = D Theoretically, coffee may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Coffee contains caffeine. Caffeine is reported to have antiplatelet activity (8028,8029). Theoretically, the caffeine in coffee might increase the risk of bleeding when used concomitantly with these agents. However, this interaction has not been reported in humans. There is some evidence that caffeinated coffee might increase the fibrinolytic activity in blood (8030).

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, concomitant use of coffee and antidiabetes drugs might interfere with blood glucose control.  Details Coffee contains caffeine. Reports claim that caffeine might increase or decrease blood sugar levels (6024,8646).

BETA-ADRENERGIC AGONISTS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use of large amounts of coffee might increase cardiac inotropic effects of beta-agonists.  Details Coffee contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists (15).

CIMETIDINE (Tagamet) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Theoretically, cimetidine might increase the effects and adverse effects of caffeine in coffee.  Details Coffee contains caffeine. Cimetidine can reduce caffeine clearance by 31% to 42% (11736,24700).

CLOZAPINE (Clozaril) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Coffee contains caffeine. Caffeine can increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg daily inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients be more sensitive to the interaction between clozapine and caffeine (13741).

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the effects and adverse effects of caffeine found in coffee.  Details Coffee contains caffeine. Oral contraceptive drugs can decrease caffeine clearance by 40% to 65% (2714,11737).

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, coffee might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Coffee contains caffeine. Caffeine is a methylxyanthine that may inhibit dipyridamole-induced vasodilation (11770,11772,24974,37985,53795). It is recommended that methylxanthines such as caffeine, as well as methylxanthine-containing products such as coffee, be stopped 24 hours prior to pharmacological stress tests (11770). Methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing (11771).

DISULFIRAM (Antabuse) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, disulfiram might increase the risk of adverse effects from caffeine.  Details Coffee contains caffeine. In human research, disulfiram decreases the clearance and increases the half-life of caffeine (11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk of hypokalemia.  Details Coffee contains caffeine. Caffeine, especially in excessive amounts, can reduce potassium levels due to stimulation of the sodium-potassium pump (23579,37905,37953,38003,38034). Diuretics can also cause lower potassium levels.

EPHEDRINE Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, concomitant use might increase the risk of stimulant adverse effects.  Details Coffee contains caffeine. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death (1275,6486,9740,10307). Tell patients to avoid taking caffeine with ephedrine and other stimulants.

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, estrogens might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Estrogen inhibits caffeine metabolism (2714).

FLUCONAZOLE (Diflucan) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, fluconazole might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022,24978).

FLUVOXAMINE (Luvox) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, fluvoxamine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Fluvoxamine reduces caffeine metabolism (6370,38287).

LAMOTRIGINE (Lamictal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Coffee consumption can decrease the levels and clinical effects of lamotrigine.  Details A pharmacokinetic study in patients taking lamotrigine shows that consumption of coffee, both caffeinated and decaffeinated, can decrease the area under the concentration-time curve (AUC) and the peak plasma level (Cmax) of lamotrigine. Each additional cup of coffee reduced the AUC and Cmax by 4% and 3%, respectively. It is unclear whether this interaction is due to induction of lamotrigine metabolism or inhibition of lamotrigine absorption (107837).

LEVOTHYROXINE (Synthroid, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Coffee can reduce the absorption of levothyroxine.  Details In some patients, coffee can reduce levothyroxine absorption, possibly through the formation of non-absorbable complexes. A pharmacokinetic study in these patients found that 25-30 mL of espresso coffee consumed with levothyroxine tablets delayed the time to peak plasma levels by 38-43 minutes, reduced the peak plasma level (Cmax) by 19% to 36%, and reduced the area under the curve (AUC) by 27% to 36%. Coffee consumed one hour after levothyroxine did not affect absorption (16401). It is not known whether this interaction occurs with other types of coffee. Tell patients to avoid drinking coffee at the same time that they take their levothyroxine, and for up to an hour afterwards.

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt coffee withdrawal might increase the levels and adverse effects of lithium.  Details Coffee contains caffeine. Abrupt caffeine withdrawal can increase serum lithium levels (609). Two cases of lithium tremor that worsened with abrupt coffee withdrawal have been reported (609,610). There is also one case of a 2.8-fold increase in blood lithium levels after a patient taking lithium reduced his coffee consumption from 13-20 cups daily to 10 cups daily (97369).

MEXILETINE (Mexitil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, mexiletine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Mexiletine can decrease caffeine elimination by 50% (1260,11741,24981).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the risk of a hypertensive crisis.  Details Coffee contains caffeine. Caffeine has been shown to inhibit monoamine oxidase (MAO) A and B in laboratory studies (37724,37877,37912,38108). Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis (15). In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension (91086). Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

NICOTINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, concomitant use might increase the risk of hypertension.  Details Coffee contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, coffee might reduce the effects of pentobarbital.  Details Coffee contains caffeine. Theoretically, caffeine might negate the hypnotic effects of pentobarbital (13742).

PHENOTHIAZINES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, phenothiazines might increase the levels and adverse effects of caffeine. Also, coffee may bind to phenothiazines and reduce their absorption.  Details Coffee contains caffeine. Phenothiazines can reduce the metabolism of caffeine by inhibiting cytochrome P450 1A2 (CYP1A2) (23573,23574). Additionally, the tannins in coffee may bind to phenothiazines in the gastrointestinal tract and reduce their absorption (626,627).

PHENYLPROPANOLAMINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure (11738). Phenylpropanolamine also seems to increase caffeine serum levels (13743).

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, coffee might increase the levels and clinical effects of pioglitazone.  Details Coffee contains caffeine. Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone (108812). However, the exact mechanism of this interaction is unclear.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Concomitant use of caffeine and quinolones can decrease caffeine clearance and increase effects and risk of adverse effects (606,607,608,23555,24695,24696,24697).

RILUZOLE (Rilutek) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.  Details Coffee contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce metabolism of one or both agents (11739).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = C Theoretically, concomitant use might increase stimulant adverse effects.  Details Coffee contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects (11832).

TERBINAFINE (Lamisil) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, terbinafine might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Terbinafine decreases the clearance of intravenous caffeine by 19% (11740).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Theoretically, coffee might increase the levels and adverse effects of theophylline.  Details Coffee contains caffeine, which can increase theophylline levels (11741,11862,24984).

TRICYCLIC ANTIDEPRESSANTS (TCAs) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, TCAs might bind with coffee constituents when taken at the same time.  Details In vitro research suggests that the tannins in coffee might cause precipitation of TCAs (626,627). However, this effect has not been reported in humans.

VERAPAMIL (Calan, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of caffeine.  Details Coffee contains caffeine. Verapamil increases plasma caffeine concentrations by 25% (11741).

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, oats may have additive effects with antidiabetic agents and might increase the risk of hypoglycemia.  Details Consuming oats can decrease blood glucose in patients with diabetes (4980,4982,6266,103345). In those who require insulin, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control (103336).

INSULIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Concomitant use of oats and insulin might increase the risk of hypoglycemia.  Details In patients with insulin-dependent type 2 diabetes, taking oats 100 grams daily for 2 days reduces the insulin dose required to achieve metabolic control (103336).

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CNS DEPRESSANTS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Concomitant use of passion flower with sedative drugs might cause additive effects and side effects.  Details Research in animals and humans shows that passion flower has sedative effects which can be additive when used with sedative medications like lorazepam (8007,19235,19236,19429,68309,104206).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Possible •  Level of Evidence = D Theoretically, passion flower might decrease the effects of CYP3A4 substrates.  Details In vitro research suggests that passion flower can induce CYP3A4 enzymes, albeit to a much lower degree than rifampin, a known CYP3A4 inducer (110704).

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, passion flower might reduce the bioavailability of OATP2B1 and OATP1A2 substrates.  Details In vitro research shows that the passion flower constituents apigenin and vitexin inhibit OATP2B1 and OATP1A2. This inhibition may be dose-dependent. One specific high-flavonoid passion flower extract (Valverde) seems to inhibit OATP2B1 and OATP1A2, while another extract with a lower flavonoid concentration (Arkocaps) shows less potent inhibition (105095). OATPs are responsible for the uptake of drugs and other compounds into the body; however, the specific activities of OATP2B1 and OATP1A2 are not well characterized.

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AMILORIDE (Midamor) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Probable •  Level of Evidence = B Amiloride can modestly reduce zinc excretion and increase zinc levels.  Details Clinical research shows that amiloride can reduce urinary zinc excretion, especially at doses of 10 mg per day or more. This zinc-sparing effect can help to counteract zinc losses caused by thiazide diuretics, but it is unlikely to cause zinc toxicity at usual amiloride doses (830,11626,11627,11634). The other potassium-sparing diuretics, spironolactone (Aldactone) and triamterene (Dyrenium), do not seem to have a zinc-sparing effect.

ATAZANAVIR (Reyataz) Interaction Rating = Minor Be watchful with this combination. Severity = Insignificant •  Occurrence = Probable •  Level of Evidence = B Zinc modestly reduces levels of atazanavir, although this effect does not seem to be clinically significant.  Details Clinical research shows that zinc might decrease serum atazanavir levels by chelating with atazanavir in the gut and preventing its absorption (93578). Although a single dose of zinc sulfate (Solvazinc tablets) 125 mg orally does not affect atazanavir concentrations in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate 125 mg daily for 2 weeks reduces plasma levels of atazanavir by about 22% in these patients. However, despite this decrease, atazanavir levels still remain at high enough concentrations for the prevention of HIV virus replication (90216).

CEPHALEXIN (Keflex) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Zinc might decrease cephalexin levels by chelating with cephalexin in the gut and preventing its absorption.  Details A pharmacokinetic study shows that zinc sulfate 250 mg taken concomitantly with cephalexin 500 mg decreases peak levels of cephalexin by 31% and reduces the exposure to cephalexin by 27%. Also, taking zinc sulfate 3 hours before cephalexin decreases peak levels of cephalexin by 11% and reduces the exposure to cephalexin by 18%. By decreasing cephalexin levels, zinc might increase the risk of treatment failure. This effect does not occur when zinc is taken 3 hours after the cephalexin dose (94163). To avoid an interaction, advise patients take zinc sulfate 3 hours after taking cephalexin.

CISPLATIN (Platinol-AQ) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, zinc might interfere with the therapeutic effects of cisplatin.  Details Animal research suggests that zinc stimulates tumor cell production of the protein metallothionein, which binds and inactivates cisplatin (11624,11625). It is not known whether zinc supplements or high dietary zinc intake can cause clinically significant interference with cisplatin therapy. Cisplatin might also increase zinc excretion.

INTEGRASE INHIBITORS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, taking zinc along with integrase inhibitors might decrease the levels and clinical effects of these drugs.  Details Zinc is a divalent cation. Pharmacokinetic studies have shown that other divalent cations such as calcium and iron can decrease blood levels of the integrase inhibitor dolutegravir through chelation (93578,93579).

PENICILLAMINE (Cuprimine, Depen) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Zinc might reduce the levels and clinical effects of penicillamine.  Details By forming an insoluble complex with penicillamine, zinc interferes with penicillamine absorption and activity. Zinc supplements reduce the efficacy of low-dose penicillamine (0.5-1 gram/day), but do not seem to affect higher doses (1-2.75 gram/day), provided dosing times are separated (2678,4534,11605). Advise patients to take zinc and penicillamine at least 2 hours apart.

QUINOLONE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Zinc can decrease the levels and clinical effects of quinolones antibiotics.  Details Quinolones form complexes with zinc in the gastrointestinal tract, reducing absorption of both the quinolone and zinc if taken at the same time (828,2682,3046,11600). Advise patients to take these drugs at least 2 hours before, or 4-6 hours after, zinc supplements.

RITONAVIR (Norvir) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = B Zinc modestly reduces levels of ritonavir.  Details Clinical research shows that zinc might reduce serum ritonavir levels by chelating with ritonavir in the gut and preventing its absorption (93578). In patients with HIV, ritonavir is taken with atazanavir to prevent the metabolism and increase the effects of atazanavir. A pharmacokinetic study shows that, in patients being treated with atazanavir/ritonavir, co-administration of zinc sulfate (Solvazinc tablets) 125 mg as a single dose or as multiple daily doses for 2 weeks reduces plasma levels of ritonavir by about 16% (90216). However, atazanavir levels still remains high enough to prevent HIV virus replication. Therefore, the decrease in ritonavir levels is not likely to be clinically significant.

TETRACYCLINE ANTIBIOTICS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Zinc might reduce levels of tetracycline antibiotics.  Details Tetracyclines form complexes with zinc in the gastrointestinal tract, which can reduce absorption of both the tetracycline and zinc when taken at the same time (3046,4945). Taking zinc sulfate 200 mg with tetracycline reduces absorption of the antibiotic by 30% to 40% (11615). Demeclocycline and minocycline cause a similar interaction (4945). However, doxycycline does not seem to interact significantly with zinc (11615). Advise patients to take tetracyclines at least 2 hours before, or 4-6 hours after, zinc supplements to avoid any interactions.

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General ...Orally, caffeinated or decaffeinated coffee is well tolerated in moderate amounts.
Most Common Adverse Effects:
Orally: Drinking coffee containing caffeine can cause agitation, anxiety, chest pain, diuresis, gastric distress, headache, insomnia, nervousness, premature heart rate, ringing in the ears, and vomiting. These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly). With chronic caffeine use, especially in large amounts, habituation, tolerance, and psychological dependence can occur.
Abrupt discontinuation of caffeine may result in physical withdrawal symptoms, including anxiety, decreased physical energy, depressed mood, difficulty concentrating, drowsiness, fatigue, headache, irritability, reduced alertness, and rhinorrhea.
Rectally: Coffee enemas have been linked to proctocolitis, severe electrolyte abnormalities, and septicemia leading to death.

Cardiovascular ...Orally, coffee containing caffeine can cause chest pain and premature heartbeat (8042,111045). These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042). Excessive doses of caffeine can cause massive catecholamine release and subsequent sinus tachycardia (11832,11838,13734,13735).
Although acute administration of caffeine can cause increased blood pressure, regular consumption does not seem to increase either blood pressure or pulse, even in hypertensive patients (1451,1452,2722,13739,105312). Drinking one or more cups of caffeinated coffee daily also doesn't seem to increase the risk of developing hypertension in habitual coffee drinkers (8033,13739,111037).
Epidemiological research has found that regular caffeine intake of up to 400 mg daily, or approximately 4 cups of caffeinated coffee, is not associated with an increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453,105310), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453,105310), or cardiovascular disease (CVD) in general (37805,98806,104882). However, some observational research suggests that drinking at least 1 cup of coffee per week is associated with a 40% increased risk of atrial fibrillation, with the highest incidence of atrial fibrillation occurring in adults consuming at least 6 cups daily (111042). Also, one large, observational study found a J-shaped association between regular coffee consumption and the risk of developing acute coronary syndromes. Moderate consumption of less than 300 mL daily (about 1.3 cups) was associated with a lower risk of developing acute coronary syndromes, whereas regular consumption of 300 mL daily or more was associated with an increased risk (11318). In contrast, other observational research in people without a history of CVD has found that drinking more than 6 cups of coffee daily does not appear to be associated with an increased risk of developing coronary heart disease (14343). Also, in people with a history of CVD, population research has found that coffee consumption is associated with a reduction in CVD-related mortality (97373,97374,103997,103998,104594,104595,104882,105308,105311,105313,105314); however not all research agrees (112735). However, in current smokers with a history of acute coronary syndrome, consuming more than 3 cups of coffee daily is associated with more than a two-fold increased risk of overall mortality (105313). Also, population research in patients with severe hypertension, but not mild hypertension, suggests that drinking at least two cups of coffee daily is associated with a 2-fold increase in CVD mortality compared with non-coffee drinkers (111027).
Caffeine intake may pose a greater cardiovascular risk to subjects who are not regular caffeine users. Population research suggests that drinking caffeinated coffee might trigger a myocardial infarction (MI) in some people. People who drink one or fewer cups of coffee daily and are sedentary and have multiple risk factors for heart disease have a significantly increased risk of MI within an hour after drinking coffee. However, this risk appears diminished in people who routinely consume greater amounts of coffee on a daily basis (14497). In another population study, caffeinated coffee consumption was associated with an increased risk of ischemic stroke in subjects who didn't regularly drink coffee (38102).
Boiled coffee that is prepared without a filter appears to increase serum cholesterol and triglyceride levels (1353,4200,8036,8539). Drinking one liter of strong, unfiltered coffee daily for two weeks can raise serum cholesterol by 10% and serum triglycerides by 36% (1353). Tell patients to use coffee filters since these effects do not seem to occur with filtered coffee (4200,8036,8539).
Coffee can adversely affect homocysteine levels. Higher homocysteine levels have been associated with CVD. One liter of unfiltered strong coffee daily for two weeks can increase plasma homocysteine levels by 10% (1353). The same amount of filtered strong coffee appears to raise plasma homocysteine levels by 20%, although there have been no head-to-head comparisons of filtered versus unfiltered coffee (3344).

Dermatologic ...Some researchers suggest symptoms such as flushed face occur during caffeine withdrawal. However, withdrawal symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Endocrine ...Orally, excessive doses of caffeine can cause massive catecholamine release and subsequent metabolic acidosis, hyperglycemia, and ketosis (13734). Other symptoms include hypokalemia and respiratory alkalosis (11832,11838,13735).
Some evidence shows that caffeine, a constituent of coffee, is associated with fibrocystic breast disease, breast cancer, and endometriosis in females; however, this is controversial since findings are conflicting (8043). Restricting caffeine intake in patients with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). Population research suggests that exposure to caffeine is not associated with an increased risk of endometriosis (91035).
A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages, such as coffee, and the incidence of invasive breast cancer in models adjusted for demographic, lifestyle, and reproductive factors (108806). Also, a dose-response analysis of 2 low-quality observational studies has found that high consumption of caffeine is not associated with an increased risk of breast cancer (108807).

Gastrointestinal ...Orally, coffee containing caffeine can cause gastric distress and vomiting. These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). There is also some evidence that consumption of three or more cups of caffeinated coffee might increase the risk of Helicobacter pylori infection (8034).
Caffeine withdrawal symptoms such as nausea and vomiting have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).
Rectally, at least 5 cases of proctocolitis related to the use of coffee enemas have been reported (96868,103273).

Genitourinary ...The caffeine found in coffee is a known diuretic and may increase voiding, give a sense of urgency, and irritate the bladder (37874,37961,104580). In males with lower urinary tract symptoms, caffeine intake increased the risk of interstitial cystitis/painful bladder syndrome (38115). Excessive caffeine consumption may worsen premenstrual syndrome. Consumption of up to 10 cups of caffeinated drinks daily has been associated with increased severity of premenstrual syndrome (38177).

Hematologic ...There is evidence that coffee containing caffeine shortens whole blood fibrinolysis time (8030).
Rectally, coffee enemas have been linked to severe electrolyte abnormalities leading to death (3026,3347,3349,6652)

Hepatic ...Boiled coffee that is prepared without a filter appears to increase liver aminotransferase enzymes. Tell patients to use coffee filters since these effects do not seem to occur with filtered coffee (8539).

Immunologic ...Caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).
Rectally, coffee enemas have been linked to septicemia leading to death (3026,3347,3349,6652).

Musculoskeletal ...Orally, there is preliminary evidence that use of greater than four cups of coffee daily can increase the risk of rheumatoid factor positive rheumatoid arthritis, but this association has not been confirmed (6482).
Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can increase urinary excretion of calcium (2669,10202,11317). Females identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass (2669). However, moderate caffeine intake of less than 400 mg daily does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317,98806).
Caffeine withdrawal symptoms, such as muscle tension and muscle pains, have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Neurologic/CNS ...Orally, coffee containing caffeine can cause agitation, headache, insomnia, and nervousness, . These effects are more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,11832,11838,13734,13735).
Combining ephedra with coffee can increase the risk of adverse effects, due to the caffeine contained in coffee. Jitteriness, seizures, and temporary loss of consciousness have been associated with the combined use of ephedra and caffeine (2729).
Some researchers suggest that symptoms such as headache; tiredness and fatigue; decreased energy, alertness, and attentiveness; drowsiness; decreased contentedness; difficulty concentrating; irritability; and lack of clear-headedness are typical of caffeine withdrawal (13738). Withdrawal symptoms such as delirium, nervousness, and restlessness have also been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Ocular/Otic ...Orally, coffee containing caffeine can cause ringing in the ears. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). Coffee containing caffeine also increases intraocular pressure, starting about 30 minutes after consumption and persisting for at least 90 minutes. Decaffeinated coffee does not appear to affect intraocular pressure (8540).

Oncologic ...The association between consumption of coffee and pancreatic cancer is controversial. Coffee may increase the incidence of some types of pancreatic cancers, but it may decrease other types (8535,8536,8537). Some studies do not support this association, especially in patients that have never smoked (8038,8040,93878,103999). Patients who are at risk of pancreatic cancer (pancreatitis) should limit their consumption of coffee.
People who consume 2-4 or more cups of caffeinated coffee dail might have a significantly increased risk of developing lung cancer (13191,90177). But drinking decaffeinated coffee seems to be associated with a decreased risk of lung cancer (13191).
Coffee consumption has also been associated at various times with an increased risk of breast cancer, bladder cancer, colon cancer, and other types of cancers, but there's no good evidence that coffee consumption increases cancer risk (8039,8040,8041). Most human studies that have examined caffeine or coffee intake have found that they do not play a role in the development of various cancers, including breast or most gastric cancers (91054,91076,98806). However, drinking caffeinated coffee might increase the risk of gastric cardia cancer (91076).

Psychiatric ...Orally, coffee containing caffeine can cause anxiety. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734). With chronic use, especially in large amounts, habituation, tolerance, and psychological dependence can occur (3719). Other researchers suggest symptoms such as depressed mood are typical of caffeine withdrawal (13738). However, withdrawal symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Pulmonary/Respiratory ...Caffeine withdrawal symptoms such as rhinorrhea have been described. However, these symptoms may be due to nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Renal ...Orally, coffee containing caffeine can cause diuresis. This is more likely with increasing intake of caffeine and in certain populations (e.g., children, elderly) (8042,13734).

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General ...Orally, oats are well tolerated.
Most Common Adverse Effects:
Orally: Abdominal distension, bloating, flatulence, and unpleasant taste.
Topically: Burning, contact dermatitis, itching, and redness.

Dermatologic ...Topically, oat-containing preparations can cause contact dermatitis (12515). Redness, burning, and itchiness have also been reported (103340).

Gastrointestinal ...When consumed orally, oats provide fiber. Increasing fiber in the diet can cause flatulence, bloating, abdominal distention, and unpleasant taste. To minimize side effects, doses should be slowly titrated to the desired level. These adverse effects usually subside with continued use (12514).
In patients who have difficulty chewing food, or those with conditions that decrease small bowel motility, oat bran may cause bezoars (concretions) and intestinal obstruction. Oats and oat bran are unlikely to cause obstruction without other causative factors (4979,4985).

Immunologic ...In a case report, a 45-year-old male developed acute generalized urticaria, facial angioedema, and dyspnea immediately after consuming oat flour. The reaction resolved after emergency care for anaphylaxis. Further investigation revealed an IgE-mediated hypersensitivity reaction to oat proteins (113490).

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General ...Orally, passion flower is well tolerated.
Most Common Adverse Effects:
Orally: Confusion, dizziness, hypersensitivity, and sedation.

Cardiovascular ...There is a case report involving a 34-year-old female who was hospitalized with severe nausea, vomiting, drowsiness, prolonged QT interval, and episodes of nonsustained ventricular tachycardia following use of passion flower extract tablets (Sedacalm, Bioplus Healthcare), 1500 mg on day 1 and 2000 mg on day 2 to relieve stress. All symptoms resolved within one week after passion flower was discontinued (6251).

Genitourinary ...The alkaloids harman and harmaline, which are sometimes found in small amounts in passion flower, have been reported to have uterine stimulant activity (4,11020,95037).

Hematologic ...Orally, passion flower has been reported to cause epistaxis in one clinical trial (95038). Vasculitis has also been reported with use of a specific herbal product (Relaxir) produced mainly from the fruits of passion flower (6).

Hepatic ...There is debate about whether passion flower contains cyanogenic glycosides. Several related Passiflora species do contain these constituents (3), including Passiflora edulis, which is associated with liver and pancreatic toxicity (7).

Immunologic ...An idiosyncratic hypersensitivity reaction characterized by urticaria and cutaneous vasculitis has been reported in a 77-year-old male with rheumatoid arthritis after taking a specific combination product that included passion flower extract (Naturest) (68308). It is unclear if these effects were caused by passion flower or other ingredients.
In clinical trials, passion flower has been reported to cause allergy symptoms including sinus irritation; however, the frequency of these events was statistically nonsignificant when compared to treatment with midazolam 15 mg (95038).

Musculoskeletal ...Orally, passion flower has been reported to cause muscle relaxation in a clinical trial (95038).

Neurologic/CNS ...Orally, sedation, dizziness, ataxia, and confusion have been reported in clinical trials. However, these events generally do not necessitate discontinuation (8007,15391,15392,95036,95038). Altered consciousness has been reported with use of a specific herbal product (Relaxir) produced mainly from the fruits of passion flower (6).

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General ...Orally, zinc is well tolerated in doses below the tolerable upper intake level (UL), which is 40 mg daily for adults. Topically, zinc is well tolerated.
Most Common Adverse Effects:
Orally: Abdominal cramps, diarrhea, metallic taste, nausea and vomiting (dose-related).
Topically: Burning, discoloration, itching, stinging, and tingling when applied to irritated tissue.
Intranasally: Bad taste, dry mouth, headache, irritation, reduced sense of smell.
Serious Adverse Effects (Rare):
Orally: There have been cases of acute renal tubular necrosis, interstitial nephritis, neurological complications, severe vomiting, and sideroblastic anemia after zinc overdose.
Intranasally: There have been cases where intranasal zinc caused permanent loss of smell (anosmia).

Dermatologic ...Topically, zinc can cause burning, stinging, itching, and tingling when applied to inflamed tissue (6911,8623,87297). Zinc oxide can be deposited in the submucosal tissue and cause dark discoloration of the skin. This can occur with prolonged topical application to intact skin, application to eroded or ulcerated skin, or penetrating traumatic exposure, and also parenteral administration (8618).
In rare cases, oral zinc has resulted in worsened acne (104056), skin sensitivity (6592), a leishmanial reaction with a macular rash that occurred on exposed parts of the body (86935), eczema (104055), systemic contact dermatitis (109457), and the development of severe seborrheic dermatitis (86946).

Gastrointestinal ...Orally, zinc can cause nausea (338,2663,2681,6592,6700,18216,106230,106233,106227,113661), vomiting (2663,2681,6519,6592,96069,96074), a metallic or objectionable taste in the mouth (336,338,6700,11350,18216,106902,113661), abdominal cramping (6592,96069), indigestion (87227), heartburn (96069), dry mouth (87533), and mouth irritation (336,2619). When used orally in amounts above the tolerable upper intake level, zinc may cause irritation and corrosion of the gastrointestinal tract (331,86982,87315,106902), watery diarrhea (1352), epigastric pain (2663,2681), and severe vomiting (2663,2681).
Intranasally, zinc can cause bad taste, dry mouth, and burning and irritation of the throat (8628,8629).
When used topically as a mouth rinse, zinc may cause tooth staining (90206).

Hematologic ...There is concern that high daily doses of zinc, above the tolerable upper intake level (UL) of 40 mg per day, might increase the risk of copper deficiency, potentially leading to anemia and leukopenia (7135,112473). To prevent copper deficiency, some clinicians give a small dose of copper when zinc is used in high doses, long-term (7303).

Hepatic ...There are two cases of liver deterioration in patients with Wilson disease following initiation of treatment with zinc 50-200 mg three times daily. The mechanism of action is not understood, and the event is extremely uncommon (86927,87470).

Immunologic ...Daily doses of 300 mg of supplemental zinc for 6 weeks appear to impair immune response (7135). A case of erythematosus-like syndrome, including symptoms such as fever, leg ulcers, and rash, has been reported following intake of effervescent tablets (Solvezink) containing zinc 45 mg (87506). In another case, severe neutropenia was reported after taking supplemental zinc 900 mg daily for an unknown duration (112473).

Musculoskeletal ...Orally, zinc may cause body aches in children (113661).

Neurologic/CNS ...Zinc-containing denture adhesives can cause toxicity if used more frequently than recommended for several years. Case reports describe hyperzincemia, low copper levels, blood dyscrasias, and neurological problems, including sensory disturbances, numbness, tingling, limb weakness, and difficulty walking in patients applying denture adhesive multiple times daily for several years (17092,17093,90205,90233). Due to reports of zinc toxicity associated with use of excessive amounts of zinc-containing denture adhesives for several years, GlaxoSmithKline has reformulated Polygrip products to remove their zinc content (17092,17093).
Intranasally (8628) and orally (87534), zinc can cause headache. When used orally in amounts above the tolerable upper intake level (UL), zinc may cause central nervous system (CNS) symptoms including lethargy, fatigue, neuropathy, dizziness, and paresthesia (2663,2681,87369,87470,87533,87534,112473).

Oncologic ...There is concern that zinc might worsen prostate disease. For example, some preliminary evidence suggests that higher dietary zinc intake increases the risk for benign prostatic hyperplasia (6908). Epidemiological evidence suggests that taking more than 100 mg of supplemental zinc daily or taking supplemental zinc for 10 or more years doubles the risk of developing prostate cancer (10306). Another large-scale population study also suggests that men who take a multivitamin more than 7 times per week and who also take a separate zinc supplement have a significantly increased risk of prostate cancer-related mortality (15607). However, a large analysis of population research suggests that there is no association between zinc intake and the risk of prostate cancer (96075).

Pulmonary/Respiratory ...There are several hundred reports of complete loss of sense of smell (anosmia) that may be permanent with use of zinc gluconate nasal gel, such as Zicam (11306,11155,11707,16800,16801,17083,86999,87535). Loss of sense of smell is thought to be dose related but has also been reported following a single application (11306,11155,11707,16800). Patients often report having sniffed deeply when applying the gel, then experiencing an immediate burning sensation, and noticing anosmia within 48 hours (17083). On June 16, 2009, the US Food and Drug Administration (FDA) advised patients not to use a specific line of commercial zinc nasal products (Zicam) after receiving 130 reports of loss of smell (16800). The manufacturer of these products had also received several hundred reports of loss of smell related to its intranasal zinc products (16801). Zinc sulfate nasal spray was used unsuccessfully for polio prophylaxis before the polio vaccine was developed. It caused loss of smell and/or taste, which was sometimes permanent (11713). Animal studies suggest that zinc sulfate negatively affects smell, possibly by damaging the olfactory epithelium and neurons (11156,11703,11704,11705,11706). Zinc gluconate nasal spray has not been tested for safety in animals or humans. The clinical studies of intranasal zinc have not described anosmia as an adverse effect, but testing was not done to see if zinc use adversely affected sense of smell (6471,8628,8629,10247). Also, these clinical studies reported tingling or burning sensation in the nostril, dry nose, nose pain, and nosebleeds.
When used in amounts above the tolerable upper intake level (UL), zinc may cause flu-like symptoms including coughing (2663).

Renal ...In overdose, zinc can cause acute renal tubular necrosis and interstitial nephritis (331,1352,87338).

Other ...Occupational inhalation of zinc oxide fumes can cause metal fume fever with symptoms including fatigue, chills, fever, myalgias, cough, dyspnea, leukocytosis, thirst, metallic taste, and salivation (331).

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