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EFFECTIVE

• Migraine headache. Oral caffeine in combination with acetaminophen, aspirin, and/or sumatriptan is approved by the US Food and Drug Administration (FDA) for treating migraine headache. Details: Taking caffeine 100-260 mg orally in combination with acetaminophen 500-2000 mg, aspirin 500 mg, and/or sumatriptan 50-100 mg is effective for treating migraine headache (2715,2716,2717,37614,37626,37816,91068). Some evidence shows that caffeine in combination with aspirin and acetaminophen may be more effective than sumatriptan in treating a migraine attack (37666). However, taking caffeine 200 mg plus ergotamine seems to be less effective than sumatriptan or calcium carbasalate plus metoclopramide (37685,38312). Caffeine is an FDA-approved product for use with analgesics for the treatment of migraine.
• Neonatal apnea. Oral or intravenous caffeine citrate is approved by the US Food and Drug Administration (FDA) for the short-term treatment of neonatal apnea in very preterm infants. Details: Using caffeine orally or intravenously improves apnea of prematurity in very preterm infants and reduces the risk of bronchopulmonary dysplasia, invasive mechanical ventilation, and neurodevelopmental impairment (6023,6371,37857,37906,38124,38344,98807,100364). The dosage approved in the FDA labeling is a single loading dose of caffeine citrate 20 mg/kg (10 mg/kg caffeine base), followed by 5 mg/kg of caffeine citrate (2.5 mg/kg caffeine base) every 24 hours for maintenance. Clinical research shows that caffeine citrate dose-dependently reduces the number of apnea episodes by at least 50% over 7-10 days of treatment (6371). Doses above 10 mg/kg daily reduce the risk of apnea, bronchopulmonary dysplasia, and problematic extubation compared with doses below 10 mg/kg/day (98807,100364). Additional clinical research shows that reinitiating caffeine treatment after termination of the original caffeine regimen, and continuing until 40 weeks postmenstrual age, reduces the incidence of intermittent hypoxia in premature infants by 46% when compared to standard care (91073). At 18-21 months of age, a history of neonatal caffeine treatment reduces the risk of long-term complications of apnea of prematurity, such as cerebral palsy or cognitive delay (37722,38340). At 11 years of age, individuals born prematurely and treated with caffeine have improved visuomotor, visuoperceptual, and visuospatial abilities when compared to those who received placebo (97452). Data on the prophylactic use of caffeine in very low birth-weight infants (less than 1500 grams and 32 weeks' gestation) are conflicting. In a meta-analysis of 11 studies, 5 show a reduced risk of apnea of prematurity, oxygen therapy, bronchopulmonary dysplasia, patent ductus arteriosus, and retinopathy of prematurity, and a reduced duration of mechanical ventilation (111491). However, other studies do not show any benefit (38125,111491). A study of infants born at 34-36 weeks' gestation shows that caffeine citrate, 10 or 20 mg/kg orally daily, reduces the number of intermittent hypoxemia episodes per hour by 61% and 67% respectively, when compared with placebo (111493). Caffeine and aminophylline have similar effectiveness for management of apnea, bradycardia, and hypoxemia, but caffeine has a wider range of safe plasma levels and lower rates of tachycardia and feeding intolerance (111492).
• Postoperative headache. Oral or intravenous caffeine is approved by the US Food and Drug Administration (FDA) for preventing headache in postoperative patients who regularly consume caffeinated products. Details: Clinical research shows that using caffeine is effective for preventing postoperative headache in patients who regularly consume caffeinated products. Intravenous caffeine does not seem to be effective in non-regular caffeine consumers. Studied doses have included 200 mg intravenously or oral doses calculated based on average daily consumption (2725,2726). Caffeine is an FDA-approved product for preventing headache in postoperative patients who regularly consume caffeinated products.
• Tension headache. Oral caffeine in combination with analgesics is approved by the US Food and Drug Administration (FDA) for treating tension headache. Details: Taking caffeine orally in combination with analgesics is effective for treating simple tension headache. Taking caffeine 100 mg alone is more effective at reducing tension headache pain when compared with placebo, but less effective than the combination of caffeine and analgesics. Caffeine 130 mg has been used with acetaminophen 1000 mg or with acetaminophen 500 mg and aspirin 500 mg. Caffeine 50 mg has been used with acetylsalicylic acid 250 mg and acetaminophen 200 mg (2718,11832,37668,37773).

LIKELY EFFECTIVE

• Mental alertness. Oral caffeine increases mental alertness. However, it might not improve performance or accuracy to the same extent achieved through adequate sleep. Details: Consumption of caffeinated beverages or caffeine supplements seems to prevent a decline in alertness and cognitive capacity when consumed throughout the day (4221,4224,36439,37727,37757,37759,38070,38075,38158,91093)(91075). Caffeine appears to be especially effective in individuals that are not regular users (91074). Taking caffeine 100-600 mg can improve alertness and speed following prolonged sleep deprivation but usually does not affect mental performance or accuracy (10205,37716,37755,37806,37992,38007,38035,38139,91049,91072)(103706,112736). Drinking coffee containing caffeine 100 mg prior to a cognitive performance test improves reaction times in people with recent poor sleep quality, and in those with adequate sleep. However, the increase in vigilance occurring in the sleep-deprived people does not bring their performance up to the level seen with adequate sleep. Also, the number of errors made by sleep-deprived people seems to increase, suggesting that caffeine may have a detrimental effect on inhibitory control (98809). Caffeine also appears to reduce cognitive impairment caused by medications such as chlorpheniramine (91058). Combining caffeine with certain other supplements may improve mental performance. Taking caffeine 80 mg with taurine seems to provide a small improvement in mental performance (9899), although this effect is not observed in sleep deprived subjects (38154). Some clinical research shows that combining caffeine 40-75 mg with glucose 37.5 grams or L-theanine 97-100 mg improves mental performance better than placebo or either substance alone (13732,37762,37903,38116); however, other clinical research shows no additional benefit from combining L-theanine and caffeine (91045).

POSSIBLY EFFECTIVE

• Athletic performance. Oral caffeine taken 30-150 minutes prior to physical activity seems to modestly improve muscle strength and physical endurance, although the magnitude of effect is variable and may be dependent on a number of patient- and activity-specific factors. Caffeine in excess of 800 mg daily can result in levels greater than those allowed by the National Collegiate Athletic Association. Details: Clinical research and meta-analyses of clinical research show that taking caffeine 2-10 mg/kg modestly improves work produced, muscle strength, physical endurance, and athletic performance (10203,11832,37648,37894,38054,38063,95955,100362,100365,100371)(103701,103703,108798,111250). Meta-analyses of studies using caffeine 3-9 mg/kg as a single dose prior to endurance time trials reports variability in results. Sports studied included running, rowing, cycling, swimming, and Nordic skiing, and included both recreational and trained athletes. Overall there was a small positive effect on time to exhaustion, endurance performance, and mean power output, and a decrease in the time needed to complete the trials when compared with placebo (98808,111497). Another meta-analysis of small clinical trials shows that the benefit of caffeine on athletic performance seems to increase with increased duration of the activity. This suggests that caffeine can improve physical endurance during athletic activities (100371). In these trials, caffeine is typically provided as a single dose 30-150 minutes prior to testing (98808), although one study suggests that taking caffeine 60 minutes prior to peak activity has the most consistent ergogenic benefits (104577). Most research has investigated the acute effects of a single dose of caffeine. The evidence is mixed as to whether chronic intake of caffeine could induce tolerance and reduce any acute ergogenic benefits. One study shows that the consistent consumption of caffeine 3 mg/kg daily for 28 days eliminates the acute benefits of caffeine in work produced when compared with placebo, suggesting the development of tolerance (95955). However, chronic use of caffeine at a dose of 6 mg/kg for 4 days does not seem to induce tolerance to an acute dose of caffeine 6 mg/kg taken 60 minutes prior to a cycling time trial in males who are moderate to high users of caffeine (104576). Similarly, a small clinical study in trained individuals shows that acute supplementation with oral caffeine 6 mg/kg about 1 hour prior to performance improves strength and endurance when compared with placebo or control, regardless of habitual caffeine consumption (108804). Differences may be due to the type of exercise, the acute dose of caffeine, the length of the chronic intake period, and/or the normal caffeine intake of the athlete. Some clinical research also shows that taking caffeine can decrease subjective feelings of exertion and fatigue during exercise such as fencing and cycling (17618,37656,91026,91058,91062). Although some other clinical studies show that caffeine does not affect perceived exertion, caffeine does seem to improve performance and cause small increases in the amount of physical work done when compared with placebo in various athletes, including cyclists, runners, basketball players, and golfers (37702,37860,37872,38031,38119,38320,91037,91077,97457,97459)(104580,108800,108804). These effects do not seem to be dependent upon the dose of caffeine (97459), although some research shows that the timing of caffeine intake and exercise may alter overall benefit, with a greater effect seen in the morning compared to the evening (97457,104580). Caffeine might improve performance in some athletic activities but not others. Some research shows that caffeine does not improve performance during athletic activities requiring a high amount of exertion over a short period of time. Such activities include sprinting and lifting (11832,37564,37758,37837,37841,37890,38319,95963,97459,112740). However, it is possible that the negative lifting studies were underpowered. Ballistic exercise, such as jumping or throwing, requires rapid increases in velocity, force, and muscle activation. A meta-analysis of 10 studies shows that caffeine in a range of doses (mean: 3 mg/kg) has a significant ergogenic effect on throwing performance and velocity (111488). A meta-analysis of small studies shows that caffeine modestly improves bench press repetitions and maximum strength, but not perceived exertion, when compared with placebo. Caffeine also tends to improve these parameters for leg presses, but the improvement does not reach significance when compared with placebo (103701). A very small study in healthy males shows that taking caffeine alone, 6 mg/kg prior to bench press exercises, has a greater ergogenic benefit than a multi-ingredient supplement containing the same dose of caffeine in combination with L-tyrosine, beta-alanine, L-citrulline maleate, arginine alpha-ketoglutarate, and L-taurine (111250). A meta-analysis of small clinical studies in female team-sport athletes shows that caffeine improves specific team-sport skills but has no effect on perceived exertion or agility tests performed after exertion (108799). Conversely, a small individual clinical study shows that taking caffeine 6.5 mg/kg 60 minutes before strength training decreases perceived exertion while increasing the number of repetitions of both upper and lower limb exercises by 17% to 33% over placebo (104581). Most studies suggest that there is significant inter-individual variability in response to caffeine for improvement of athletic performance (100365). These differences might be due, at least in part, to genotype (100370), although research is conflicting. Caffeine is metabolized by the cytochrome P450 1A2 (CYP1A2) enzyme. One small clinical trial in resistance-trained males shows that taking caffeine 6 mg/kg improves resistance exercise performance in those homozygous for the CYP1A2 rs762551 polymorphism (AA) when compared with those without or heterozygous for that polymorphism (CC or A/C, respectively) (100370). However, another clinical study in trained male athletes shows that taking oral caffeine 4 mg/kg about 30 minutes prior to performance decreases handgrip strength by about 13% in individuals with the CC genotype when compared with placebo, but not in those with the AA or A/C genotypes. No groups experienced an improvement in vertical jump performance (108803). Another small clinical study suggests that CYP1A2 genotype does not affect exercise performance in athletes 60 minutes after taking caffeine 3 mg/kg. In addition, the ADORA2A genotype, which plays a role in caffeine sensitivity, does not seem to affect exercise performance benefits from caffeine (104578). However, these studies are small and further research is needed to clarify how these polymorphisms may impact the athletic performance benefits of caffeine. Limited research has also evaluated the use of a caffeine mouth rinse, with mixed findings. Two very small clinical studies in healthy trained males shows that rinsing the mouth with 25 mL of water containing caffeine 85 or 300 mg for 5-10 seconds does not affect athletic performance or time to exhaustion while cycling when compared with placebo (103709,108801). However, another small study in healthy Taekwondo athletes fasting for Ramadan suggests that using a mouth rinse containing caffeine 6 mg/kg, ten seconds prior to exertion, modestly reduces perceived exertion and modestly improves kick performance when compared with using a placebo rinse (103710). Similarly, another small clinical study in healthy, resistance-trained males shows that rinsing the mouth with 25 mL of a solution containing caffeine 3%, but not 1% or 2%, reduces perceived exertion and increases muscular endurance, but not strength, when compared with placebo. The mouth rinse was used for 5 seconds immediately prior to a strength test or once per minute for 2 minutes during a muscular endurance test (108802). Preliminary clinical research has also investigated the use of caffeine in combination with other ingredients, such as sodium bicarbonate however these studies have not demonstrated clear benefits in athletic performance over taking caffeine alone (112740).
• Bronchopulmonary dysplasia. Intravenous caffeine may reduce the risk for bronchopulmonary dysplasia in preterm infants. Details: Population research has found that initiating caffeine treatment prior to the third day of life in premature infants is associated with a reduced risk of developing bronchopulmonary dysplasia compared to later initiation of treatment with caffeine. Additionally, a meta-analysis of available clinical research shows that high-dose caffeine (40-80 mg/kg loading dose, 20 mg/kg daily maintenance) lowers the risk of bronchopulmonary dysplasia when compared with standard dosing (20 mg/kg loading dose, followed by 5-10 mg/kg daily maintenance). However, small sample sizes and high heterogeneity limit the validity of these findings (97462,100364).
• Diabetes. Dietary caffeine seems to be beneficial for the prevention of type 2 diabetes; it is unclear if it is beneficial for the prevention of gestational diabetes. Also, it is unclear if oral caffeine is beneficial in patients with type 1 or type 2 diabetes. Details: Total caffeine consumption from beverages such as coffee or tea is associated with a lower risk of developing type 2 diabetes. This effect appears to be dose-dependent (11353,14313,37850,37871,91040,100368). For example, an increase of 200 mg daily caffeine intake seems to be associated with a 14% decrease in the incidence of type 2 diabetes (91055). Additionally, in North American males, consuming caffeine 417 mg daily from coffee or tea is associated with a 20% lower risk of developing type 2 diabetes when compared with those consuming less than 37 mg daily. North American females consuming at least 258 mg of caffeine daily from coffee or tea seem to have a 10% to 30% lower risk of developing type 2 diabetes when compared with those consuming less than 140 mg daily (11353). Japanese adults who consume at least 416 mg of caffeine daily from beverages including coffee or green tea seem to have a 33% lower risk of developing type 2 diabetes compared to those who consume no more than 57 mg daily. The risk reduction appears to be more pronounced in Japanese females when compared with males (14313). It is unclear if caffeine is beneficial in adults with diabetes. A few small studies show that caffeine consumption may further reduce insulin sensitivity in patients with type 2 diabetes, gestational diabetes, or those at risk for developing diabetes (13744,37653,37820). Caffeine consumption has also been evaluated during pregnancy. An observational study has found that self-reported consumption of beverages containing up to 100 mg of caffeine at 16-22 weeks' gestation is associated with a 47% lower risk of developing gestational diabetes when compared with no intake (108814). Research regarding the effects of caffeine in patients with type 1 diabetes shows conflicting results. One study shows that taking caffeine 250 mg twice daily for 2 weeks can reduce the incidence of elevated blood sugar at night in patients with type 1 diabetes (37660). However, another study in patients with type 1 diabetes shows that taking caffeine 200 mg daily for 3 months may increase the ability to perceive hypoglycemic symptoms when compared with placebo, although overall glycemic control does not seem to be affected (6024).
• Memory. Oral caffeine seems to be beneficial for short-term memory recall in college students and extroverted personalities. It is unclear if oral caffeine is beneficial for introverted personalities or other populations. Details: Taking a single dose of caffeine 65-200 mg orally daily seems to improve memory function in some individuals such as college students and people with extroverted personalities. A small study shows that taking caffeine does not improve memory function in individuals with introverted personalities (37845,38071,91080).
• Obesity. Oral caffeine, when taken in combination with ephedrine or as a component of green tea, seems to be beneficial for weight loss, short-term. Details: Taking caffeine orally, in combination with ephedrine or as a component of green tea, seems to help reduce weight, short-term (695,696,1704,8647,16892,37617,37831). Caffeine 192 mg in combination with ephedra 20-90 mg per day for 6 months seems to cause a modest weight reduction (5.3 kg) in people with a body mass index (BMI) between 25-40 kg/m². This combination, along with limiting fat intake to 30% of calories and moderate exercise, also seems to reduce body fat, decrease low-density lipoprotein (LDL) cholesterol, and increase high-density lipoprotein (HDL) cholesterol. However, even in carefully screened and monitored otherwise healthy adults, caffeine/ephedra combinations can cause small changes in blood pressure and heart rate (8647). Preliminary clinical research also shows that taking 1000 mg of a proprietary combination product containing caffeine and multiple other ingredients (Prograde Metabolism) twice daily for 8 weeks in conjunction with dieting reduces body weight, fat mass, waist circumference, and hip circumference by 1.5%, 5%, 1.8%, and 1.3%, respectively, when compared with dieting alone (40802).
• Pain (acute). Oral caffeine, when taken in combination with acetaminophen, propyphenazone, ibuprofen, or other pain-relieving agents, seems to be beneficial for acute pain. Details: Clinical research shows that taking caffeine 50-130 mg in combination with acetaminophen, propyphenazone, ibuprofen, or other pain-relieving agents can reduce acute pain when compared with the effects of pain-relieving agents alone (37587,37904,38036,38303,91038). Adding ≥100 mg caffeine to treatment with acetaminophen or ibuprofen results in 5% to 10% more patients that achieve at least 50% of maximum pain relief for over 4 hours when compared to treatment with acetaminophen or ibuprofen alone (91038).
• Postdural puncture headache. Oral or intravenous caffeine seem to be beneficial for preventing postdural puncture headache. Details: Using caffeine 300 mg orally or 500 mg in 1,000 mL normal saline intravenously seems to help treat and prevent postdural puncture headache (2727,2728). Using a combination of ergotamine and caffeine seems to be less effective than gabapentin for treating this condition (38147). Lower doses of oral caffeine may not be beneficial. Clinical research shows that oral caffeine, 75-125 mg, does not decrease the risk of postdural headache (91022).

POSSIBLY INEFFECTIVE

• Atrial fibrillation. Oral caffeine does not seem to prevent atrial fibrillation after cardiopulmonary bypass. In addition, it might increase the risk of gastrointestinal side effects. Details: In adults undergoing surgery with cardiopulmonary bypass, taking caffeine 400 mg every 8 hours for 6 doses does not seem to reduce the risk of developing atrial fibrillation during the first three post-operative days. This clinical study was stopped prior to the completion of recruitment after an interim analysis showed increased incidence of postoperative nausea and vomiting, and no effect on the incidence of atrial fibrillation (97451).
• Attention deficit-hyperactivity disorder (ADHD). Oral caffeine does not seem to reduce symptoms of ADHD in children. Details: Most research suggests caffeine does not significantly reduce ADHD symptoms in children when used at tolerable doses (10755,10756,10757,10758,10759,10760). The use of caffeine in adolescents and adults with ADHD has not been studied.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. It is unclear if oral caffeine prevents cognitive decline with aging. Details: Population research from a small cohort of elderly females shows that caffeine intake of more than 371 mg daily is associated with an attenuation in cognitive decline when compared to less than 30 mg daily. This is equivalent to the difference seen over a 7 year span of age. Caffeinated coffee consumption, but not caffeinated chocolate, tea, or cola, was associated with this attenuation in cognitive decline (91088).
• Alzheimer disease. It is unclear if oral caffeine is beneficial for preventing dementia; the available research is conflicting. Details: Population research from the UK Biobank has found that caffeine intake up to 400 mg daily is associated with a 24% to 34% reduced risk of developing Alzheimer disease when compared with lower intake. Conversely, population research from the Rush Memory and Aging Project in the US has found that caffeine intake of more than 100 mg daily is associated with a 41% increased risk of developing Alzheimer disease when compared with lower intake. However, when those with mild cognitive impairment at baseline or cases diagnosed within 2 years of follow-up are excluded, these findings become insignificant (108810).
• Asthma. Oral caffeine seems to modestly improve airway function for up to 4 hours in patients with mild to moderate asthma. However, it is unclear if oral caffeine has a clinically significant effect on asthma symptoms or quality of life. Details: Taking caffeine 9 mg/kg orally appears to modestly improve airway function for up to 4 hours in people with mild to moderate asthma (37907,37915). However, more research is needed to determine the appropriate dose, whether any benefit is clinically significant, or whether tolerance occurs with chronic dosing.
• Cancer pain. It is unclear if intravenous caffeine is beneficial for cancer pain. Details: Clinical research shows that receiving caffeine 200 mg intravenously once daily for 2 days results in a significant reduction in pain intensity by 0.833 points on the NRS scale when compared with control in patients receiving opioids for pain from advanced cancer (91081).
• Cognitive function. It is unclear if oral caffeine improves cognitive performance in trained athletes. Details: A meta-analysis of small studies in trained adult athletes shows that consumption of a low to moderate amount of caffeine 15-60 minutes prior to exercise and during exercise improves attention performance, but not reaction time or inhibitory control, when compared with placebo (108797). The validity of these findings is limited by unclear reporting.
• Dementia. It is unclear if oral caffeine is beneficial for preventing dementia or improving behavior in patients with dementia. Details: Population research from the Women's Health Initiative has found that caffeine intake of more than 175 mg daily is associated with a 26% reduced risk of developing probable dementia or global cognitive impairment when compared to less than 175 mg daily in postmenopausal adults 65-80 years of age (97458). Population research from the UK Biobank has found that caffeine intake up to 400 mg daily is associated with a 17% to 26% reduced risk for developing all-cause dementia when compared with lower intake. Conversely, population research from the Rush Memory and Aging Project in the US has found that caffeine intake of more than 100 mg daily is associated with a 35% increased risk of developing all-cause dementia when compared with lower intake. However, when those with mild cognitive impairment at baseline or cases diagnosed within 2 years of follow-up are excluded, these findings become insignificant (108810). Caffeine consumption has also been evaluated in patients with dementia. A cross-sectional study in patients with dementia in a care home has found that intake of 'normal' to 'high' amounts of caffeine are associated with reduced agitation and other behavioral symptoms when compared to 'low' intakes of caffeine (104574).
• Depression. It is unclear if oral caffeine is beneficial for depression prevention. Details: Some population research found that caffeine intake is associated with an increased incidence of depressive symptoms in pediatric patients (37839,38162). However, other population research found that caffeinated beverage intake is associated with a decreased incidence of depression in adults (37969,38165,91067,100366).
• Electroconvulsive therapy (ECT) augmentation. Although there has been interest in using intravenous caffeine sodium benzoate to augment electroconvulsive therapy, there is insufficient reliable information about the clinical effects of caffeine for this condition.
• Exercise-induced hypoxemia. It is unclear if oral caffeine is beneficial for hypoxemia associated with exercise. Details: Preliminary clinical research in athletes experiencing exercise-induced hypoxemia shows that taking caffeine 8 mg/kg can improve exercise ventilation, but not ventilatory response or oxygen saturation, when compared with placebo (37750).
• Exercise-induced muscle soreness. It is unclear if oral caffeine is beneficial for reducing muscle soreness during exercise. Details: There is conflicting clinical evidence as to whether caffeine can reduce exercise-induced muscle pain. Some evidence shows that taking caffeine 100 mg or 10 mg/kg can reduce muscle pain during exercise when compared with placebo (37622,38146). However, the effect of lower doses is unclear. Some evidence shows that taking caffeine 5 mg/kg may reduce exercise-induced muscle pain when compared with placebo (37747,91050), while other evidence suggests that taking caffeine 2-5 mg/kg does not affect muscle pain during exercise (38141).
• Gallbladder disease. It is unclear if increased dietary caffeine intake reduces the risk of developing gallstones. Details: Consumption of caffeinated beverages that provide 400 mg or greater of caffeine per day 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 per day has the greatest reduction in risk (3345).
• Hepatitis C. It is unclear if increased dietary caffeine reduces the risk for hepatitis C-associated severe liver inflammation, although it may reduce the risk of developing advanced fibrosis. Details: A meta-analysis of population research has found that regular consumption of caffeine at doses of at least 123 mg daily is associated with a 48% reduced risk of advanced liver fibrosis when compared to lower caffeine intake in patients with hepatitis C virus (95947). An individual population study also found that higher intake of caffeine from coffee is associated with reduced severity of liver fibrosis in patients with chronic hepatitis C virus. For these patients, the risk of advanced fibrosis is reduced by 14% for each 67 mg of caffeine (37896). However, caffeine intake does not appear to be associated with a reduced risk of moderate to severe liver inflammation in patients with hepatitis C (95947).
• Hypnic headache. It is unclear if oral caffeine reduces the pain associated with this rare condition. Details: Anecdotal evidence suggests that drinking a cup of coffee containing caffeine before bed or upon waking up may help alleviate pain associated with hypnic headaches (38078).
• Hypotension. It is unclear if oral caffeine is beneficial in people with low blood pressure. Details: Preliminary clinical research shows that consuming caffeinated beverages increase blood pressure in elderly people with postprandial hypotension (11834,11835).
• Intermittent claudication. It is unclear if oral caffeine is beneficial for intermittent claudication. Details: Taking a single dose of caffeine 6 mg/kg orally seems to improve walking distance, muscular strength, and endurance in patients with intermittent claudication; however, balance seems to be reduced (38038).
• Liver disease. It is unclear if oral caffeine is beneficial for liver disease prevention. Details: Population research found that there is an inverse association between intake of coffee and the incidence of liver cirrhosis (37576,37608). However, it is unclear if this effect of coffee is attributable to caffeine, since other caffeinated beverages do not show this effect.
• Narcolepsy. It is unclear if oral caffeine is beneficial for narcolepsy. Details: A small clinical study in patients with narcolepsy shows that taking caffeine 200 mg daily in the morning for 1 week does not affect reaction time, but modestly reduces drowsiness, when compared with baseline (103698). The validity of this finding is limited by the lack of a statistical comparison between the treatment and placebo groups.
• Neonatal resuscitation. It is unclear if oral caffeine improves the likelihood for successful extubation in preterm infants. Details: Preliminary clinical research in extremely preterm infants requiring mechanical ventilation within the first 5 days of birth shows that early administration of caffeine, given as a loading dose of caffeine citrate 20 mg/kg followed by a maintenance dose of 5 mg/kg daily until extubation, does not reduce mortality or shorten time to first successful extubation when compared to giving a bolus dose of caffeine citrate 20 mg/kg just prior to extubation (97461).
• Nocturnal enuresis. Reducing caffeine intake might reduce the frequency of nocturnal enuresis episodes in children. Details: Preliminary clinical research in children aged 6-15 years with primary nocturnal enuresis shows that limiting caffeine intake to less than 30 mg daily reduces the mean number of bedwetting episodes from 3.5 to 2.4 per week, when compared with no change in the group with intakes of 80-100 mg daily. The probability of bedwetting in the caffeine restricted group was about 14% lower than that in the control group (111495).
• Nonmelanoma skin cancer. It is unclear if oral caffeine is beneficial for nonmelanoma skin cancer prevention. Details: A review of available population research shows that increased caffeine intake from any source is associated with a 14% reduction in the risk of developing nonmelanoma skin cancer. Consumption of caffeinated coffee, but not decaffeinated coffee, is associated with an 18% reduced risk (97465).
• Parkinson disease. Although consuming caffeinated beverages might reduce the risk of developing Parkinson disease, it is unclear if oral caffeine is beneficial for improving symptoms. Also, oral caffeine does not seem to prevent tardive dyskinesia. Details: It is unclear whether caffeine improves some symptoms of Parkinson disease, as results from clinical research are conflicting (91069,95951,95954,103705). One clinical study in Parkinson disease patients with extreme daytime somnolence shows that taking caffeine 100 mg twice daily for 3 weeks and then 200 mg twice daily for 3 weeks results in modest improvements in rigidity and bradykinesia, but inconsistent improvements in drowsiness, when compared with placebo (91069). Other clinical research shows that caffeine 200 mg twice daily does not lead to improvements in motor severity, cognition, or somnolence after 6, 12, or 18 months when compared with placebo (95954). Furthermore, a large retrospective study has found that caffeine consumption of more than 300 mg daily for 18 months in conjunction with dopaminergic therapy does not slow the rate of Parkinson disease progression. This research also shows that a reported consumption of caffeine greater than 300 mg, in conjunction with creatine 10 grams daily for 18 months, may accelerate the rate of Parkinson disease progression (95951). The retrospective nature of this study limits the validity of these findings. Caffeine does not appear to be helpful for reducing the risk of tardive dyskinesia. A retrospective analysis has found no definitive difference in onset of tardive dyskinesia in Parkinson patients consuming more than 204 mg caffeine daily when compared with those consuming less than 68 mg daily (91090). Despite these mainly negative findings, large-scale epidemiological studies have found that people who consume caffeinated beverages, such as coffee, tea, and cola, have a decreased risk of Parkinson disease (37931,91060,91071,103705). Males consuming 3-4 cups (28 oz) of caffeinated coffee per day, or 421-2716 mg total caffeine, seem to have the lowest risk of developing this condition. However, a lower risk is also associated with consumption of as little as 124-208 mg of caffeine (6022). In females, more moderate caffeinated coffee consumption, such as 1-3 cups per day, seems to be best (1238). Caffeine does not appear to provide additional protection from Parkinson disease in cigarette smokers (9236,91060).
• Postoperative ileus. It is unclear if oral caffeine is beneficial for improving bowel recovery following colorectal resection. Details: A small clinical study in adults undergoing elective laparoscopic colon or rectal resection with primary anastomosis shows that caffeine citrate 100 mg three times daily, starting on the morning of postoperative day 1, reduces the time to self-reported first bowel movement by about 18 hours when compared with placebo. There was no difference between groups in time to self-reported first flatus (108808). Another small study in adults undergoing elective laparoscopic colectomy shows that taking caffeine 100 mg or 200 mg three times daily does not reduce the mean time to first bowel movement, colonic transit time, or length of hospital stay when compared with placebo (111484). However, a meta-analysis of these two clinical trials shows that taking caffeine does not decrease the time to the first stool or length of hospital stay when compared with control (112732).
• Postoperative pain. It is unclear if intravenous caffeine is beneficial for reducing opioid consumption in adults undergoing surgery. Details: A small clinical study in adults undergoing laparoscopic colorectal and gastrointestinal surgery shows that intravenous caffeine citrate 200 mg at the initiation of surgical closure has no effect on cumulative opioid consumption through postoperative day 3 when compared with placebo. In fact, post-hoc analysis with adjustment for age, sex, comorbidities, history of anxiety or depression, and open surgical conversion suggests an increase in opioid consumption with administration of caffeine when compared with placebo (108809).
• Pre-eclampsia. It is unclear if oral caffeine intake affects the risk of gestational hypertension or pre-eclampsia. Details: a meta-analysis of 10 observational studies including about 115,000 pregnant people did not find an association between the level of caffeine intake during pregnancy and the risk of developing gestational hypertension or pre-eclampsia (111485).
• Stroke. It is unclear if oral caffeine is beneficial for stroke prevention. Details: Population research has found that increased intake of either caffeinated or decaffeinated coffee is associated with a decreased risk of stroke in females (37804). However, it is not clear if the effect of coffee is attributable to the caffeine component.
• Tinnitus. It is unclear if oral caffeine is beneficial in patients with chronic tinnitus. Details: A small clinical study in adults with chronic tinnitus shows that taking a single dose of caffeine 300 mg improves mood and quality of life at 1 hour when compared with baseline. (108805). The lack of statistical comparison to the placebo group limits the validity of these findings. More evidence is needed to rate the effectiveness of caffeine for these uses.

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There is insufficient reliable information available about the effectiveness of Cassia nomame.

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POSSIBLY INEFFECTIVE

• Obesity. Oral guggul does not seem to reduce body weight in patients who are overweight or obese. Details: Several small clinical studies in overweight or obese individuals shows that taking guggul 1.5-4 grams daily for 4-12 weeks or standardized tablets containing guggul (Medohar) 1.5-3 grams daily for 4 weeks does not reduce body weight when compared with no treatment or placebo (54447,54502,54511). Another clinical study in patients with hypercholesterolemia shows that taking a standardized guggul extract 1-2 grams three times daily for 8 weeks does not improve body weight when compared with placebo (10371). Guggul has also been evaluated in combination with other ingredients. One small clinical study in overweight individuals shows that taking guggul 250 mg in combination with phosphate 550 mg, garcinia 250 mg, and L-tyrosine 250 mg three times daily for 6 weeks, along with exercise and calorie restriction, reduces body weight and body fat percentage when compared to baseline, but not when compared with placebo (8152). It is unclear if these findings are due to guggul, other ingredients, or the combination.

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Acne. It is unclear if oral guggul is beneficial in patients with acne. Details: A very small clinical study in patients with nodulocystic acne shows that taking guggul, providing guggulsterone 25 mg, twice daily for 3 months leads to similar reductions in inflammatory lesions and the risk for relapse when compared with tetracycline (3268).
• Hemorrhoids. Topical guggul has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small study in adults with symptomatic mild to moderate (first- and second-degree) internal hemorrhoids shows that application of a cream containing sesame oil and aqueous extracts of guggul and Allium ampeloprasum as a thin layer to the anus twice daily for 3 weeks improves anal irritation and itching, bleeding, pain, defecation discomfort, and swelling sense when compared to baseline. In contrast, patients using a placebo cream experienced an improvement only in anal itching (105751). The poor study methodology and lack of statistical comparison to the placebo group limit the validity of these findings.
• Hypercholesterolemia. Several small, low-quality clinical studies in Indian populations suggest that oral guggul may reduce cholesterol levels in patients with hypercholesterolemia; however, more recent evidence in patients on Western diets contradicts these findings. Details: A small clinical study in patients with hypercholesterolemia following a Western diet shows that taking guggul 1-2 grams three times daily for 8 weeks increases low-density lipoprotein (LDL) cholesterol by 9% to 10% with no improvements in total cholesterol, triglycerides, or high-density lipoprotein (HDL) cholesterol when compared with placebo (10371). Another small clinical study in adults with hyperlipidemia and low to moderate cardiovascular risk shows that taking a methanolic extract of guggul 200 mg along with an aqueous extract of Terminalia and Indian gooseberry 450 mg three times daily for 3 months does not improve total, LDL, or HDL cholesterol levels or triglyceride levels when compared with placebo (105741). This is in contrast to several low-quality studies of guggul in Indian populations, which show that taking guggul extract (guggulipid) 1-2.25 grams two to three times daily for up to 16 weeks seems to lower total cholesterol, LDL cholesterol, and triglyceride levels when compared with baseline measures, placebo, or other controls (366,3267,8158,51219,54485,54497,54508). Also, some clinical research shows that taking a specific guggul extract fraction called "Fraction A" 500 mg three times daily for up to 75 weeks can reduce cholesterol and triglycerides in Indian patients with hypercholesterolemia (54492,54501). Most of the studies with positive findings were published in the 1970s and 1980s and may not be generalizable to patients on Western diets or taking conventional antihyperlipidemic agents, most of which were approved after the publication of these findings.
• Osteoarthritis. It is unclear if oral guggul is beneficial in patients with osteoarthritis. Details: Two small clinical studies in patients with osteoarthritis show that taking guggul may improve pain and other symptoms of osteoarthritis, measured using the Western Ontario and McMaster Universities Arthritis Index (WOMAC) assessment, when compared to baseline (54453,111720). One study used guggul (containing 3.5% guggulsterones) 500 mg three times daily for 2 months (54453) and the other used a polyherbal ayurvedic formulation, abha guggulu, 1500 mg two times daily for 1 month (111720). The validity of these findings is limited by the lack of a comparator group.
• Rheumatoid arthritis (RA). It is unclear if oral guggul is beneficial in patients with RA. Details: A small, uncontrolled clinical study in patients with RA shows that taking guggul 1 gram three times daily for 4 months improves symptoms of RA when compared to baseline (54512). The validity of these findings is limited by a lack of placebo group. More evidence is needed to rate guggul for these uses.

(Read more about GUGGUL)

POSSIBLY EFFECTIVE

• Back pain. Oral willow bark extract has been evaluated for the treatment of back pain, with promising results. Details: Clinical research in patients with chronic low back pain shows that taking a standardized willow bark extract providing salicin 120 mg or 240 mg daily for 4 weeks reduces lower back pain and decreases the need for rescue analgesia when compared with placebo. Salicin 240 mg appears to be more effective than salicin 120 mg, and significant pain relief may be observed after 1 week of high-dose use (6456). Additional research suggests that taking willow bark extract providing salicin 240 mg daily for 4 weeks is as effective as rofecoxib (Vioxx) for lower back pain (12804).

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Ankylosing spondylitis. Although there has been interest in using oral willow bark for pain associated with ankylosing spondylitis, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Common cold. Although there has been interest in using oral willow bark for common cold symptoms, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Dysmenorrhea. Although there has been interest in using oral willow bark for dysmenorrhea, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Gout. Although there has been interest in using oral willow bark for gout, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Headache. Although there has been interest in using oral willow bark for headache, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Influenza. Although there has been interest in using oral willow bark for pain and fever associated with influenza, including swine flu, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Joint pain. Oral willow bark has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research in patients with joint pain shows that taking capsules of a specific combination product (Instaflex Joint Support, Direct Digital) containing glucosamine sulfate 500 mg, methylsufonlylmethane 167 mg, white willow bark extract 83 mg, ginger root concentrate 17 mg, boswellia extract 42 mg, turmeric root extract 17 mg, cayenne 40 m H.U. 17 mg, and hyaluronic acid 1.3 mg three times daily for 8 weeks reduces joint pain severity by 37% compared to only 16% with placebo. However, the specific combination product does not appear to significantly improve joint stiffness or function when compared with placebo (89560). It is unclear if these findings are due to willow bark, other ingredients, or the combination.
• Myalgia. Although there has been interest in using oral willow bark for myalgia, there is insufficient reliable information about the clinical effects of willow bark for this purpose.
• Obesity. Oral willow bark has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research suggests that willow bark in combination with ephedra and cola nut might cause modest weight loss in overweight and obese people. Willow bark 600 mg daily (containing 90 mg salicin) in divided doses given for 3 months in combination with these central nervous system stimulants might cause a 2 kg reduction in weight (12811). However, this combination may not be appropriate due to safety concerns associated with ephedra. Ephedra is banned in the US due to severe adverse effects (10055).
• Osteoarthritis. Small clinical studies suggest that oral willow bark extract may improve symptoms of osteoarthritis, although some conflicting evidence exists. Details: Some preliminary clinical research in patients with osteoarthritis shows that taking willow bark extract standardized to contain 240 mg of salicin daily for 2 weeks produces moderate analgesic activity when compared with placebo (12474,86490). Additional research shows that taking a specific willow bark extract (Optovit actiFLEX, Hermes Arzneimittel GmbH) standardized to contain salicin 120-240 mg daily for 6 weeks improves swelling, tenderness, and physical function similarly to conventional non-steroidal anti-inflammatory drugs (NSAIDs) (91406). However, other research shows that taking willow bark extract standardized to 240 mg of salicin daily for 6 weeks does not improve pain, stiffness, or physical function when compared with placebo (12475).
• Rheumatoid arthritis (RA). It is unclear if oral willow bark is beneficial in patients with RA. Details: Clinical research in a small number of patients with RA shows that willow bark extract standardized to 240 mg of salicin daily for 6 weeks does not improve pain when compared with placebo (12475). However, it is possible this study was underpowered to detect a significant difference in pain in these patients. More evidence is needed to rate willow bark for these uses.

(Read more about WILLOW BARK)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Arrhythmia. Although there has been interest in using oral yerba mate for arrhythmia, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Athletic performance. It is unclear if oral yerba mate is beneficial for improving athletic performance. Details: A small clinical study shows that taking yerba mate 5 grams orally daily for 5 days prior to a cycling exercise shortens time to completion by 2% and modestly improves absolute power when compared with placebo in trained athletes (96471).
• Cognitive function. It is unclear if oral yerba mate is beneficial for improving cognitive function. Details: Preliminary clinical research shows that drinking a single beverage containing one tablespoon of yerba mate does not improve vigilance, working memory, reaction time, or accuracy when compared with decaffeinated coffee controls in healthy females ages 17-35 years (86712).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral yerba mate for CFS, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Depression. Although there has been interest in using oral yerba mate for depression, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Diabetes. It is unclear if oral yerba mate is beneficial in patients with diabetes. Details: Preliminary clinical research shows that drinking yerba mate tea, prepared by steeping 6.6 grams of leaves for 10 minutes in 330 mL of boiling water, three times daily for 60 days decreases fasting blood glucose by up to 17% and glycated hemoglobin (HbA1c) by 0.85% when compared with baseline in patients with type 2 diabetes (86693). The validity of these findings is limited by the lack of a comparator group.
• Dyslipidemia. It is unclear if oral yerba mate is beneficial in patients with dyslipidemia. Details: A meta-analysis of 7 small, mostly low to moderate quality clinical studies in adults shows that taking yerba mate orally does not reduce levels of total, low-density lipoprotein (LDL) cholesterol, or triglycerides or improve high-density lipoprotein (HDL) cholesterol when compared with placebo or dietary intervention (111738). However, the validity of this study is limited by the heterogeneity of the included studies which enrolled patients with varying conditions and used various forms and doses of yerba mate. Other clinical research in patients with dyslipidemia or hypercholesterolemia shows that drinking 330 mL of tea containing yerba mate 20 mg/mL three times daily for 40 days reduces LDL cholesterol levels by 9% and increases HDL cholesterol levels by 4% when compared with baseline. The effects of yerba mate were similar between patients on low- to moderate-intensity statin therapy and those not taking statins. Drinking yerba mate tea did not affect triglyceride levels (86657).
• Fatigue. Although there has been interest in using oral yerba mate for fatigue, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Headache. Although there has been interest in using oral yerba mate for headache, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Heart failure. Although there has been interest in using oral yerba mate for heart failure, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Impaired glucose tolerance (Prediabetes). It is unclear if oral yerba mate is beneficial in patients with prediabetes. Details: Clinical research shows that drinking yerba mate tea, prepared by steeping 6.6 grams of leaves for 10 minutes in 330 mL of boiling water, three times daily for 60 days reduces glycated hemoglobin (HbA1C) by 0.4%, but not fasting blood glucose levels, when compared with baseline in patients with prediabetes (86693). The validity of these findings is limited by the lack of a comparator group.
• Joint pain. Although there has been interest in using oral yerba mate for joint pain, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Kidney stones (nephrolithiasis). Although there has been interest in using oral yerba mate for nephrolithiasis, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Mental alertness. Although there has been interest in using oral yerba mate for mental alertness, there is insufficient reliable information about the clinical effects of yerba mate for this purpose.
• Muscle strength. It is unclear if oral yerba mate improves muscle strength. Details: A small clinical crossover study in males shows that consuming a beverage containing 3 grams of yerba mate (Matte Leão, Valinhos Brazil) 1-hour prior to bench press and leg press strength training does not improve muscle strength when compared with placebo (111739).
• Obesity. It is unclear if oral yerba mate is beneficial in patients with obesity. Details: Although some observational research in healthy patients has found that high consumption of yerba mate is associated with increased weight (99322), most preliminary clinical research in adults with obesity shows that consuming yerba mate might improve some parameters (11866,92152,96470). Two, small, randomized controlled trials in obese Korean adults shows that taking yerba mate 3 grams daily, in 2-3 divided doses, for 6-12 weeks does not reduce weight, body mass index, or lipid levels when compared with placebo. Taking yerba mate modestly improved other measures, such as fat mass, waist-hip ratio, and waist circumference when compared with baseline, but these results were not consistent between trials and the studies may have been inadequately powered to detect a difference between groups (92152,96470).
• Osteoporosis. It is unclear if oral yerba mate is beneficial in patients with osteoporosis. Details: In an observational study, consumption of at least 1 liter of yerba mate tea daily for a minimum of 4 years was associated with higher lumbar spine and femoral neck bone densities, with increases of 9.7% and 6.2%, respectively (17184). In contrast, a small case-control study found no association between yerba mate consumption and markers of bone resorption and formation in postmenopausal adults, regardless of the duration of yerba mate consumption (96468). Neither study identified an association between fracture rates; however, these studies may have been inadequately powered to detect a difference between groups (17184,96468).
• Parkinson Disease. It is unclear if oral yerba mate is beneficial in preventing Parkinson disease. Details: A small observational study has found that high consumption of yerba mate tea is associated with 59% to 63% lower odds of being diagnosed with Parkinson disease when compared with no consumption of yerba mate (106860).
• Urinary tract infections (UTIs). Although there has been interest in using oral yerba mate for UTIs, there is insufficient reliable information about the clinical effects of yerba mate for this purpose. More evidence is needed to rate yerba mate for these uses.

(Read more about YERBA MATE)

LIKELY SAFE ...when used orally, parenterally, or rectally and appropriately. Caffeine has Generally Recognized As Safe (GRAS) status in the US (4912,98806). Caffeine is also an FDA-approved product and a component of several over-the-counter and prescription products (4912,11832). According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, doses of caffeine up to 400 mg daily are 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 caffeine 400 mg daily is not associated with increased risk of major chronic diseases, such as cardiovascular disease or cancer, in healthy adults (98806). This amount of caffeine is similar to the amount of caffeine found in approximately 4 cups of coffee. Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine from caffeine-containing natural ingredients such as coffee or green tea does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

POSSIBLY UNSAFE ...when used orally, long-term or in high doses (91063). Chronic use, especially in large amounts, can produce tolerance, habituation, psychological dependence, and other adverse effects (3719). Acute use of high doses, typically above 400 mg daily, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine from caffeine-containing natural ingredients such as coffee or green tea does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

LIKELY UNSAFE ...when used orally in very high doses. The fatal acute oral dose of caffeine is estimated to be 10-14 grams (150-200 mg/kg). Serious toxicity can occur at lower doses depending on variables in caffeine sensitivity such as smoking, age, or prior caffeine use (11832,95700,97454,104573). Caffeine products sold to consumers in highly concentrated or pure formulations are considered to a serious health concern because these products have a risk of being used in very high doses. Concentrated liquid caffeine can contain about 2 grams of caffeine in a half cup. Powdered pure caffeine can contain about 3.2 grams of caffeine in one teaspoon. Powdered pure caffeine can be fatal in adults when used in doses of 2 tablespoons or less. As of 2018, these products are considered by the FDA to be unlawful when sold to consumers in bulk quantities (95700).

CHILDREN: POSSIBLY SAFE
when used orally or intravenously and appropriately in neonates under the guidance of a healthcare professional (6371,38340,38344,91084,91087,97452). ...when used orally in amounts commonly found in foods and beverages in children and adolescents (4912,11833,36555). Daily intake of caffeine in doses of less than 2.5 mg/kg daily are not associated with significant adverse effects in children and adolescents (11733,98806). Keep in mind that only the amount of ADDED caffeine must be stated on product labels. The amount of caffeine from caffeine-containing natural ingredients such as coffee or green tea does not need to be provided. This can make it difficult to determine the total amount of caffeine in a given product.

PREGNANCY: POSSIBLY SAFE
when used orally in amounts commonly found in foods. Intakes of caffeine should be monitored during pregnancy. Caffeine crosses the human placenta, but is not considered a teratogen (38048,38252,91032). 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 (2708,2709,2710,2711,9606,16014,16015,98806,108814). In some studies consuming amounts over 200 mg daily is associated with a significantly increased risk of miscarriage (16014,37960). This increased risk seems to occur in those 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, up to 300 mg daily can be consumed during pregnancy without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations (11733,98806). However, observational research in a Norwegian cohort found that caffeine consumption is associated with a 16% increased odds of the baby being born small for gestational age when compared with no consumption (100369,103707). The same Norwegian cohort found that low to moderate caffeine consumption during pregnancy is not associated with changes in neurodevelopment in children up to 8 years of age (103699). 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 or tea.

PREGNANCY: POSSIBLY UNSAFE
when used orally in amounts over 300 mg daily. Caffeine crosses the placenta, producing fetal blood concentrations similar to maternal levels (4260,98806). 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 below 300 mg daily during pregnancy. This is similar to the amount of caffeine in about 3 cups of coffee or tea. Additionally, 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 (2709,2711,91033,91048,95949). In a cohort of mother/infant pairs with a median maternal plasma caffeine level of 168.5 ng/mL (range 29.5-650.5 ng/mL) during pregnancy, birth weights and lengths were lower in the 4th quartile of caffeine intake compared with the 1st. By age 7, heights and weights were lower by 1.5 cm and 1.1 kg respectively. In another cohort of mother/infant pairs with higher maternal pregnancy plasma caffeine levels, median 625.5 ng/mL (range 86.2 to 1994.7 ng/mL), heights at age 8 were 2.2 cm lower, but there was no difference in weights (109846).

LACTATION: POSSIBLY SAFE
when used orally in amounts commonly found in foods. Caffeine intake should be closely monitored while breast-feeding. During lactation, breast milk concentrations of caffeine are thought to be approximately 50% of serum concentrations and caffeine peaks in breastmilk approximately 1-2 hours after consumption (23590).

LACTATION: POSSIBLY UNSAFE
when used orally in large amounts. Caffeine is excreted slowly in infants and may accumulate. Caffeine can cause sleep disturbances, irritability, and increased bowel activity in breast-fed infants exposed to caffeine (2708,6026).

(Read more about CAFFEINE)

There is insufficient reliable information available about the safety of Cassia nomame.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid using.

(Read more about CASSIA NOMAME)

POSSIBLY SAFE ...when the prepared gum resin is used orally and appropriately. It has been used with apparent safety in clinical trials for up to 24 weeks (3267,3268,10371). There is insufficient reliable information available about the safety of guggul when used topically.

PREGNANCY: LIKELY UNSAFE
when used orally; avoid using. Guggul gum resin appears to stimulate menstrual flow and the uterus (12).

LACTATION:
Insufficient reliable information available; avoid using.

(Read more about GUGGUL)

POSSIBLY SAFE ...when used orally and appropriately, short-term. Willow bark has been used safely for up to 12 weeks (6456,12474,12475,12804,12811,86473,91406).

CHILDREN: POSSIBLY UNSAFE
when used orally for viral infections. Salicylic acid and aspirin are contraindicated in children with viral infections (12801). Although Reye's syndrome has not been reported, the salicin constituent in willow bark is similar to aspirin and might pose the same risk.

PREGNANCY:
Insufficient reliable information available; avoid using.

LACTATION: POSSIBLY UNSAFE
when used orally. Willow bark contains salicylates which are excreted in breast milk and have been linked to adverse effects in breast-fed infants (12802,12803).

(Read more about WILLOW BARK)

POSSIBLY SAFE ...when used orally and appropriately, short-term (11866). Yerba mate has been safely used in doses of 3 grams daily for up to 12 weeks (92152,96469,96470).

POSSIBLY UNSAFE ...when yerba mate is used orally in large amounts or for prolonged periods of time. Drinking approximately 1-2 liters, or 4-8 cups, of yerba mate daily is associated with an increased risk of cancer, including esophageal, stomach, kidney, bladder, cervical, prostate, lung, renal cell, and possibly laryngeal and mouth cancer (1528,1529,1530,1531,11863,11864,92150). Yerba mate also contains caffeine. Acute use of high doses of caffeine (more than 400 mg per day), which is found in more than 8-10 cups of yerba mate, has been associated with significant adverse effects such as tachyarrhythmia and sleep disturbances (11832). Drinking yerba mate in amounts greater than 12-15 cups daily (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 yerba mate, 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.

CHILDREN: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, renal cell, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150,86595,86614,86700,86701). However, teratogenic studies have not been performed. Yerba mate also contains caffeine. Caffeine crosses the placenta, producing fetal blood concentrations similar to parental levels. 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). It is generally recommended to avoid consuming more than 300 mg of caffeine daily, or around 6-7 cups of yerba mate daily, when pregnant (2708). High doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants (9891,86618). Caffeine in doses of greater than 300 mg daily has also been associated with spontaneous abortion, premature delivery, and low birth weight (2709,2711), although one retrospective study found that consuming yerba mate tea during pregnancy was not associated with preterm or small for gestational age births (13113). However, this study did not consider the amount of yerba mate or caffeine consumed, only the frequency of consumption. Some research has 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).

LACTATION: POSSIBLY UNSAFE
when used orally. Yerba mate is associated with an increased risk of cancer, including esophageal, kidney, bladder, cervical, prostate, lung, renal cell, and possibly mouth and laryngeal cancer (1528,1529,1530,1531,11863,11864,92150). Whether carcinogenic constituents of yerba mate are transferred via breast milk is unknown. Yerba mate contains caffeine. Consumption of yerba mate might cause irritability and increased bowel activity in nursing infants (6026).

(Read more about YERBA MATE)

ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, caffeine might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Some evidence shows that caffeine is a competitive inhibitor of adenosine and can reduce the vasodilatory effects of adenosine in humans (38172). However, other research shows that 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 and 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, concomitant use might increase levels and adverse effects of caffeine.  Details Alcohol reduces caffeine metabolism. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects (6370).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Caffeine is reported to have antiplatelet activity. Theoretically, it might increase the risk of bleeding when used concomitantly with these agents (8028,8029); however, this interaction has not been reported in humans.

ANTIDIABETES DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Moderate •  Occurrence = Unlikely •  Level of Evidence = B Theoretically, taking caffeine with antidiabetes drugs might interfere with blood glucose control.  Details Data are conflicting. Reports claim that caffeine might increase or decrease blood sugar (6024,8646).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of carbamazepine and increase the risk for convulsions.  Details Animal research suggests that taking caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when taken in doses above 400 mg/kg (23559,23561). Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine 2-fold in healthy individuals (23562).

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

CLOZAPINE (Clozaril) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Caffeine might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Caffeine might increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg per day inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Although researchers speculate that caffeine might inhibit CYP1A2, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to an interaction between clozapine and caffeine (13741). In one case report, severe, life-threatening clozapine toxicity and multiorgan system failure occurred in a patient with schizophrenia stabilized on clozapine who consumed caffeine 600 mg daily (108817).

CONTRACEPTIVE DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, contraceptive drugs might increase the levels and adverse effects of caffeine.  Details Oral contraceptives decrease the rate of caffeine clearance by 40-65% (2714,11737).

CYTOCHROME P450 1A2 (CYP1A2) INHIBITORS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use might increase the levels and adverse effects of caffeine.  Details Caffeine is metabolized by CYP1A2. Theoretically, drugs that inhibit CYP1A2 may decrease the rate of caffeine clearance and increase caffeine levels (5051,11741).

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, caffeine might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Caffeine inhibits dipyridamole-induced vasodilation (11770,11772). It is recommended that methylxanthines and methylxanthine-containing products 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 use might increase the levels and adverse effects of caffeine.  Details Disulfiram decreases the rate of caffeine clearance (11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, using caffeine with diuretic drugs might increase the risk of hypokalemia.  Details 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 for stimulant adverse effects.  Details Use of ephedrine with caffeine can increase the risk of stimulatory adverse effects. 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 (1275,6486,10307).

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 Estrogen inhibits caffeine metabolism (2714,23570).

ETHOSUXIMIDE (Zarontin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of ethosuximide and increase the risk for convulsions.  Details Animal research suggests that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide (23560). However, this effect has not been reported in humans.

FELBAMATE (Felbatol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of felbamate and increase the risk for convulsions.  Details Animal research suggests that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate (23563). However, this effect has not been reported in humans.

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 Fluconazole decreases caffeine clearance by approximately 25% (11022).

FLUTAMIDE (Eulexin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, caffeine might increase the levels and adverse effects of flutamide.  Details In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide (23553). However, this effect has not been reported in humans.

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

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt caffeine withdrawal might increase the levels and adverse effects of lithium.  Details Caffeine has diuretic activity. When abruptly discontinued, it might alter the clearance of lithium (609). There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal (610).

METFORMIN (Glucophage) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, metformin might increase the levels and adverse effects of caffeine.  Details Animal research suggests that metformin can reduce caffeine metabolism (23571). However, this effect has not been reported in humans.

METHOXSALEN (Oxsoralen) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, methoxsalen might increase the levels and adverse effects of caffeine.  Details Methoxsalen reduces caffeine metabolism (23572).

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 Mexiletine reduces caffeine metabolism (1260,11741).

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 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 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, caffeine might decrease the effects of pentobarbital.  Details Caffeine might negate the hypnotic effects of pentobarbital (13742).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of phenobarbital and increase the risk for convulsions.  Details Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital (23558,23559,23561). However, the exact mechanism of this interaction is unclear.

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.  Details Phenothiazines, including perazine, chlorpromazine, levomepromazine, and thioridazine, can reduce the metabolism of caffeine by inhibiting cytochrome P450 1A2 (CYP1A2) (23573,23574).

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 Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure (11738). Phenylpropanolamine also seems to increase caffeine serum levels (13743).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of phenytoin and increase the risk for convulsions.  Details Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin (23559,23561). The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might increase the levels and clinical effects of pioglitazone.  Details 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 Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting cytochrome P450 1A2 (CYP1A2) enzyme (606,607,608,23554,23555,23556).

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 Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce the 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 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 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 = C Theoretically, caffeine might increase the levels and adverse effects of theophylline.  Details Large amounts of caffeine might inhibit theophylline metabolism (11741).

TIAGABINE (Gabitril) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might increase the levels and adverse effects of tiagabine.  Details Animal research suggests that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine (23561).

TICLOPIDINE (Ticlid) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, ticlopidine might increase the levels and adverse effects of caffeine.  Details In vitro evidence suggests that ticlopidine can inhibit caffeine metabolism (23557). However, this effect has not been reported in humans.

VALPROATE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, caffeine might reduce the effects of valproate and increase the risk for convulsions.  Details Animal research suggests that caffeine can decrease the anticonvulsant activity of valproate (23558,23559,23561,37882). However, the exact mechanism of this interaction is unclear.

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

(Read more about CAFFEINE)

(Read more about CASSIA NOMAME)

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, guggul might increase the risk of bleeding when taken with anticoagulant/antiplatelet drugs.  Details In vitro research and preliminary clinical studies suggest that guggul might have antiplatelet and anticoagulant effects (3267,9557,54503,54505).

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, guggul might increase the risk of adverse effects when taken with contraceptive drugs.  Details In vitro research shows that guggul has estrogen-alpha receptor agonist activity (12444).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, guggul might reduce the effects of CYP3A4 substrates.  Details In vitro research shows that guggul constituents known as guggulsterones can induce CYP3A4 (12444).

DILTIAZEM (Cardizem, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Guggul might reduce the effects of diltiazem.  Details A small pharmacokinetic study shows that concomitant use of guggul with diltiazem reduces the bioavailability of diltiazem (383).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, guggul might increase the risk of adverse effects when taken with estrogens.  Details In vitro research shows that guggul constituents known as guggulsterones have estrogen-alpha receptor agonist activity (12444).

PROPRANOLOL (Inderal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Guggul might reduce the effects of propranolol.  Details A small pharmacokinetic study shows that concomitant use of guggul with propranolol reduces the bioavailability of propranolol (383).

ROSUVASTATIN (Crestor) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, guggul might increase the effects and adverse effects of rosuvastatin.  Details Animal research shows that guggul increases the bioavailability and hypolipidemic effects of rosuvastatin (109584). The mechanism of this interaction is unclear.

TAMOXIFEN (Nolvadex) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, guggul might interfere with tamoxifen therapy.  Details In vitro research shows that guggul has estrogen-alpha receptor agonist activity (12444).

THYROID HORMONE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, guggul might increase the risk for adverse effects when taken with thyroid hormone therapy.  Details Animal research suggests that guggul has thyroid-stimulating effects (8153).

(Read more about GUGGUL)

ACETAZOLAMIDE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, willow bark might result in additive adverse effects associated with acetazolamide.  Details Willow bark contains salicin, a plant salicylate. Human case reports suggests that a combination of acetazolamide and salicylate increases unbound plasma levels of acetazolamide, as well as adverse effects related to acetazolamide (86481).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, willow bark might increase the risk of bleeding when taken with anticoagulant/antiplatelet drugs.  Details Willow bark has antiplatelet effects, but less so than aspirin (12810).

ASPIRIN Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, willow bark might increase the effects and adverse effects of aspirin.  Details Willow bark contains salicin, a plant salicylate. It might have an additive effect when taken with other salicylate-containing drugs such as aspirin (12808).

CHOLINE MAGNESIUM TRISALICYLATE (Trilisate) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, willow bark might increase the effects and adverse effects of choline magnesium trisalicylate.  Details Willow bark contains salicin, a plant salicylate. It might have an additive effect when taken with other salicylate-containing drugs such as choline magnesium trisalicylate (12808).

SALSALATE (Disalcid) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, willow bark might increase the effects and adverse effects of salsalate.  Details Willow bark contains salicin, a plant salicylate. It might have an additive effect when taken with other salicylate-containing drugs such as salsalate (12808).

(Read more about WILLOW BARK)

ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Yerba mate contains caffeine. Some evidence shows that caffeine is a competitive inhibitor of adenosine and can reduce the vasodilatory effects of adenosine in humans (38172). However, other research shows that caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). Still, some researchers recommend that methylxanthines, such as caffeine, as well as methylxanthine-containing products, should 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, concomitant use of alcohol and yerba mate might increase levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Alcohol reduces caffeine metabolism. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects (6370,24693).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details Yerba mate contains caffeine. Caffeine is reported to have antiplatelet activity. Theoretically, it might increase the risk of bleeding when used concomitantly with these agents (8028,8029); however, this interaction has not been reported in humans.

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

BENZODIAZEPINES Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the efficacy of benzodiazepines.  Details Yerba mate contains caffeine. Caffeine can antagonize the anxiolytic effects of benzodiazepines (24951,24952,24953,24954,24955).

BETA-ADRENERGIC AGONISTS Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the cardiac inotropic effects of beta-agonists, especially if taken in large amounts.  Details Yerba mate contains caffeine. Caffeine can increase cardiac inotropic effects of beta-agonists (15).

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might reduce the effects of carbamazepine and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when taken in doses above 400 mg/kg (23561). Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine two-fold in healthy individuals (23562).

CIMETIDINE (Tagamet) Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Likely •  Level of Evidence = B Theoretically, cimetidine might increase the levels and adverse effects of the caffeine contained in yerba mate.  Details Yerba mate contains caffeine. Cimetidine decreases 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, the caffeine in yerba mate might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Yerba mate contains caffeine. Caffeine might increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg per day inhibit clozapine metabolism (5051). Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Although researchers speculate that caffeine might inhibit CYP1A2, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to an interaction between clozapine and caffeine (13741).

CONTRACEPTIVE DRUGS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, contraceptive drugs might increase the levels and adverse effects of the caffeine contained in yerba mate.  Details Yerba mate contains caffeine. Contraceptive drugs decrease the rate of caffeine clearance by 40% to 65% (2714,11737).

CYTOCHROME P450 1A2 (CYP1A2) INHIBITORS Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of CYP1A2 inhibitors and yerba mate might increase levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Caffeine is metabolized by CYP1A2. Theoretically, drugs that inhibit CYP1A2 may decrease the rate of caffeine clearance and increase caffeine levels (5051,11741).

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, yerba mate might increase the levels and clinical effects of CYP3A4 substrates.  Details In vitro research shows that yerba mate extract inhibits CYP3A4 enzymes (105811). Theoretically, taking yerba mate may increase levels and adverse effects of CYP3A4 substrates.

DIPYRIDAMOLE (Persantine) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Yerba mate contains caffeine. Caffeine inhibits dipyridamole-induced vasodilation (11770,11772). Still, some researchers recommend that methylxanthines, such as caffeine, as well as methylxanthine-containing products, should be stopped 24 hours prior to pharmacological stress (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 = D Theoretically, disulfiram might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Disulfiram decreases the rate of caffeine clearance (15,11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the risk of hypokalemia when used concomitantly with other diuretics.  Details Yerba mate 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, the caffeine in yerba mate might increase the risk for stimulant adverse effects when used concomitantly with ephedrine.  Details Use of ephedrine with caffeine can increase the risk of stimulatory adverse effects. 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 (1275,6486,10307).

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 the caffeine in yerba mate.  Details Yerba mate contains caffeine. Estrogen inhibits caffeine metabolism (2714).

ETHOSUXIMIDE (Zarontin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of ethosuximide and increase the risk for convulsion.  Details Yerba mate contains caffeine. Animal research shows that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide (23560). However, this effect has not been reported in humans.

FELBAMATE (Felbatol) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of felbamate and increase the risk for convulsion.  Details Yerba mate contains caffeine. Animal research shows that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate (23563). However, this effect has not been reported in humans.

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 the caffeine in yerba mate.  Details Yerba mate contains caffeine. Fluconazole decreases caffeine clearance by approximately 25% (11022,24978).

FLUTAMIDE (Eulexin) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of flutamide.  Details Yerba mate contains caffeine. In vitro evidence suggests that caffeine can inhibit the metabolism of flutamide (23553). However, this effect has not been reported in humans.

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

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt withdrawal of the caffeine in yerba mate might increase serum lithium levels.  Details Yerba mate contains caffeine, which has diuretic activity. When abruptly discontinued, it might alter the clearance of lithium (609). There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal (609,610).

METFORMIN (Glucophage) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, metformin might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Animal research suggests that metformin can reduce caffeine metabolism (23571). However, this effect has not been reported in humans.

METHOXSALEN (Oxsoralen) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, methoxsalen might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. Methoxsalen reduces caffeine metabolism (23572).

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 the caffeine in yerba mate.  Details Yerba mate contains caffeine. Mexiletine decreases caffeine elimination by approximately 50% (1260,11741,24981).

MIDAZOLAM (Versed) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, use of yerba mate with midazolam might increase midazolam metabolite levels and adverse effects.  Details In vitro research shows that yerba mate extract containing 6.75% chlorogenic acid significantly inhibits the metabolism of midazolam via inhibition of cytochrome P450 3A4 (CYP3A4)(105811).

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase risk of a hypertensive crisis when used concomitantly with MAOIs.  Details Yerba mate 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 = D Theoretically, the caffeine in yerba mate might increase risk of hypertension when used concomitantly with nicotine.  Details Yerba mate 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 (2719,36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might decrease the effects of pentobarbital.  Details The caffeine in yerba mate might negate the hypnotic effects of pentobarbital (13742).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of phenobarbital and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenobarbital (23558,23561). However, the exact mechanism of this interaction is unclear.

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 the caffeine in yerba mate.  Details Yerba mate 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).

PHENYTOIN (Dilantin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Theoretically, the caffeine in yerba mate might reduce the effects of phenytoin and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research suggests that caffeine can decrease the anticonvulsant activity of phenytoin (23561). The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

PIOGLITAZONE (Actos) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and clinical effects of pioglitazone.  Details Yerba mate 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 the caffeine in yerba mate.  Details Yerba mate contains caffeine. Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting cytochrome P450 1A2 (CYP1A2) enzyme (606,607,608,23554,23555,23556).

RILUZOLE (Rilutek) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, concomitant use of riluzole and yerba mate might increase levels and adverse effects of both riluzole and the caffeine in yerba mate.  Details Yerba mate contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce the 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 of stimulant drugs and yerba mate might increase stimulant adverse effects.  Details Yerba mate contains caffeine. Due to the CNS stimulant effects of the caffeine, concomitant use 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 the caffeine in yerba mate.  Details Yerba mate contains caffeine. Terbinafine decreases the rate of caffeine clearance by 19% (11740).

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of theophylline.  Details Yerba mate contains caffeine. Caffeine decreases theophylline clearance by 23% to 29% (11741).

TIAGABINE (Gabitril) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might increase the levels and adverse effects of tiagabine.  Details Yerba mate contains caffeine. Animal research suggests that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine (23561).

TICLOPIDINE (Ticlid) Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, ticlopidine might increase the levels and adverse effects of the caffeine in yerba mate.  Details Yerba mate contains caffeine. In vitro research shows that ticlopidine can inhibit caffeine metabolism (23557). However, this effect has not been reported in humans.

VALPROATE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, the caffeine in yerba mate might reduce the effects of valproate and increase the risk for convulsions.  Details Yerba mate contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of valproate (23558,23561). However, the exact mechanism of this interaction is unclear.

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

(Read more about YERBA MATE)

General ...Caffeine in moderate doses is typically well tolerated.
Most Common Adverse Effects:
Orally: Anxiety, dependence with chronic use, diarrhea, diuresis, gastric irritation, headache, insomnia, muscular tremors, nausea, and restlessness.
Serious Adverse Effects (Rare):
Orally: Stroke has been reported rarely.

Cardiovascular ...Caffeine can temporarily increase blood pressure. Usually, blood pressure increases 30 minutes after ingestion, peaks in 1-2 hours, and remains elevated for over 4 hours (36539,37732,37989,38000,38300).
Although acute administration of caffeine can cause increased blood pressure, regular consumption does not seem to increase either blood pressure or pulse, even in mildly hypertensive patients (1451,1452,2722,38335). However, the form of caffeine may play a role in blood pressure increase after a more sustained caffeine use. In a pooled analysis of clinical trials, coffee intake was not associated with an increase in blood pressure, while ingesting caffeine 410 mg daily for at least 7 days modestly increased blood pressure by an average of 4.16/2.41 mmHg (37657). Another meta-analysis of clinical research shows that taking caffeine increases systolic and diastolic blood pressure by approximately 2 mmHg when compared with control. Preliminary subgroup analyses suggest that caffeine may increase blood pressure more in males or at doses over 400 mg (112738).
When used prior to intensive exercise, caffeine can increase systolic blood pressure by 7-8 mmHg (38308). The blood pressure-raising effects of caffeine are greater during stress (36479,38334) and after caffeine-abstinence of at least 24 hours (38241).
Epidemiological research suggests there is no association of caffeine consumption with incidence of hypertension (38190). Habitual coffee consumption also doesn't seem to be related to hypertension, but habitual consumption of sugared or diet cola is associated with development of hypertension (13739).
Epidemiological research has found that regular caffeine intake of up to 400 mg daily is not associated with increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453,103708), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453), and cardiovascular disease in general (37805,98806). One clinical trial shows that in adults with diagnosed heart failure, consumption of 500 mg of coffee does not result in an increased risk for arrhythmia during exercise (95950). However, caffeine intake may pose a greater cardiovascular risk to subjects that are not regular users of caffeine. For example, in one population study, caffeinated coffee consumption was associated with an increased risk of ischemic stroke in subjects that don't regularly drink coffee (38102). In a population study in Japanese subjects, caffeine-containing medication use was modestly associated with hemorrhagic stroke in adults that do not consume caffeine regularly (91059).
The most common side effect of caffeine in neonates receiving caffeine for apnea is tachycardia (98807).

Dermatologic ...There are several case reports of urticaria after caffeine ingestion (36546,36448,36475).

Endocrine ...Some evidence shows caffeine is associated with fibrocystic breast disease or breast cancer in females; however, this is controversial since findings are conflicting (8043,108806). Restricting caffeine in females with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages 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).
Clinical research in healthy adults shows that an increase consumption of caffeine results in increased insulin resistance (91023).

Gastrointestinal ...Gastrointestinal upset, nausea, diarrhea, abdominal pain, and fecal incontinence may occur with caffeine intake (36466,37755,37806,37789,37830,38138,38136,38223,95956,95963). Also, caffeine may cause feeding intolerance and gastrointestinal irritation in infants (6023). Perioperative caffeine during cardiopulmonary bypass surgery seems to increase the rate of postoperative nausea and vomiting (97451). Caffeine and coffee consumption have been associated with an increase in the incidence of heartburn (37545,37575,38251,38259,38267) and gastrointestinal esophageal reflux disease (GERD) (38329,37633,37631,37603).

Genitourinary ...Caffeine, a known diuretic, may increase voiding, give a sense of urgency, and irritate the bladder (37874,37961,104580). In men 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 was associated with increased severity of premenstrual syndrome (38177). Finally, population research shows that exposure to caffeine was not associated with an increased risk of endometriosis (91035).

Immunologic ...Caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).

Musculoskeletal ...Caffeine can induce or exacerbate muscular tremors (38136,37673,38161). There has also been a report of severe rhabdomyolysis in a healthy 40-year-old patient who consumed an energy drink containing 400 mg of caffeine (4 mg/kg) and then participated in strenuous weightlifting exercise (108818).
Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can release calcium from storage sites and increase its urinary excretion (2669,10202,11317,111489). Females 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, less than 300 mg daily, does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317). Premature infants treated with intravenous caffeine for apnea of prematurity, have a lower bone mineral content compared with infants who are not treated with caffeine, especially when treatment extends beyond 14 days (111489).

Neurologic/CNS ...Caffeine can cause headaches, anxiety, jitteriness, restlessness, and nervousness (36466,37694,37755,37806,37865,37830,37889,38223,95952). In adolescents, there is an inverse correlation between the consumption of caffeine and various measurements of cognitive function (104579). Insomnia is a frequent adverse effect in children (10755). Caffeine may result in insomnia and sleep disturbances in adults as well (36445,36483,36512,36531,37598,37795,37819,37862,37864,37890)(37968,37971,38091,38242,91022,92952). Additionally, caffeine may exacerbate sleep disturbances in patients with acquired immunodeficiency syndrome (AIDS) (10204). Combining ephedra with caffeine can increase the risk of adverse effects. Jitteriness, hypertension, seizures, temporary loss of consciousness, and hospitalization requiring life support has been associated with the combined use of ephedra and caffeine (2729). Finally, epidemiological research suggests that consuming more than 190 mg of caffeine daily is associated with an earlier onset of Huntington disease by 3.6 years (91078).

Ocular/Otic ...In individuals with glaucoma, coffee consumption and caffeine intake has been found to increase intraocular pressure (8540,36464,36465,37670). The magnitude of this effect seems to depend on individual tolerance to caffeine. Some research in healthy young adults shows that caffeine increases intraocular pressure to a greater degree in low-consumers of caffeine (i.e., 1 cup of coffee or less daily) when compared to high-consumers (i.e., those consuming 2 cups of coffee or more daily) (100371). The peak increase of intraocular pressure seems to occur at about 1.5 hours after caffeine ingestion, and there is no notable effect 4 hours after ingestion (36462,100371).

Oncologic ...Most human studies which have examined caffeine or methylxanthine intake have found that they do not play a role in the development of various cancers, including breast, ovarian, brain, colon, rectal, or bladder cancer (37641,37737,37775,37900,38050,38169,38220,91054,91076,108806).

Psychiatric ...Caffeine may lead to habituation and physical dependence (36355,36453,36512,36599), with amounts as low as 100 mg daily (36355,36453). An estimated 9% to 30% of caffeine consumers could be considered addicted to caffeine (36355). Higher doses of caffeine have caused nervousness, agitation, anxiety, irritability, delirium, depression, sleep disturbances, impaired attention, manic behavior, psychosis and panic attacks (36505,37717,37818,37839,37857,37982,38004,38017,38028,38072)(38079,38138,38306,38325,38331,38332,97464). Similar symptoms have been reported in a caffeine-naïve individual experiencing fatigue and dehydration after a dose of only 200 mg, with resolution of symptoms occurring within 2 hours (95952).
Withdrawal: The existence or clinical importance of caffeine withdrawal is controversial. Some researchers think that if it exists, it appears to be of little clinical significance (11839). Headache is the most common symptom, due to cerebral vasodilation and increased blood flow (37769,37991,37998). Other researchers suggest symptoms such as tiredness and fatigue, decreased energy, alertness and attentiveness, drowsiness, decreased contentedness, depressed mood, difficulty concentration, irritability, and lack of clear-headedness are typical of caffeine withdrawal (13738). Withdrawal symptoms typically occur 12-24 hours after the last dose of caffeine and peak around 48 hours (37769,36600). Symptoms may persist for 2-9 days. Withdrawal symptoms such as delirium, nausea, vomiting, rhinorrhea, nervousness, restlessness, anxiety, muscle tension, muscle pains, and flushed face have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon (2723,11839). In a case report, caffeine consumption of 560 mg daily was associated with increased suicidality (91082).

Renal ...Data on the relationship between caffeine intake and kidney stones are conflicting. Some clinical research shows that caffeine consumption may increase the risk of stone formation (37634,111498), while other research shows a reduced risk with increasing caffeine intakes (111498). A meta-analysis of 7 studies found that overall, there is an inverse relationship, with a 32% decrease in the risk of kidney stones between the lowest and highest daily intakes of caffeine (111498).

Other ...People with voice disorders, singers, and other voice professionals are often advised against the use of caffeine; however, this recommendation has been based on anecdotal evidence. One small exploratory study suggests that caffeine ingestion may adversely affect subjective voice quality, although there appears to be significant intra-individual variability. Further study is necessary to confirm these preliminary findings (2724).

(Read more about CAFFEINE)

General ...No adverse effects have been reported. However, a thorough evaluation of safety outcomes has not been conducted.

(Read more about CASSIA NOMAME)

General ...Orally, guggul seems to be generally well tolerated.
Most Common Adverse Effects:
Orally: Belching, bloating, diarrhea, headache, nausea, unpleasant taste, and vomiting. Allergic and non-allergic skin reactions.
Topically: Allergic contact dermatitis in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Rhabdomyolysis.

Dermatologic ...Orally, guggul can cause hypersensitivity reactions including rash and pruritus (10371,54457). Guggul can also cause nonallergic adverse skin reactions. The risk of skin reactions appears to be dose-dependent. In one study, the incidence of skin reactions was 3% with a dosage of 1000 mg three times daily, compared with 15% with a dosage of 2000 mg three times daily. The severity of the reactions ranged from pruritus to swelling and erythema of the face to bullous lesion on the lower legs associated with headaches, myalgias, and pruritus (13662).
Topically, guggul can cause allergic contact dermatitis (54464,54467). Also, in a small clinical study, one patient using a cream containing aqueous extracts of guggul and Allium ampeloprasum as well as sesame oil complained of rash at the application site (105751). It is unclear if this reaction was due to guggul, other ingredients, or other factors.

Gastrointestinal ...Orally, guggul can cause nausea, vomiting, loose stools, diarrhea, belching, bloating, hiccups, and mild gastrointestinal discomfort (3267,8155,8158,10371,52033,54492).

Hepatic ...A case of severe hypertransaminasemia has been reported for a 63-year-old female who took a specific product (Equisterol) containing guggulsterone and red yeast rice extract daily for 6 months. Liver function normalized after discontinuing the supplement. It is unclear if the adverse effect was due to guggulsterone, red yeast, or the combination. However, the patient had previously developed hepatotoxicity while taking lovastatin, and red yeast contains monacolin K, which is identical to lovastatin (54477). Also, a case of acute liver failure requiring liver transplantation has been reported for a previously healthy young female who used a mixed-ingredient dietary supplement containing extracts of green tea, guggul, and usnic acid. It is unclear if the hepatotoxicity was due to guggul or other ingredients; green tea has been associated with hepatotoxicity (54027).

Immunologic ...Orally, guggul can cause hypersensitivity reactions including rash and pruritus (10371,54457). In a small clinical study, two adults with hyperlipidemia developed a hypersensitivity rash, one with facial edema, within minutes of oral administration of a methanolic extract of guggul, together with Terminalia extract (105741). It is unclear if this reaction was due to guggul, Terminalia, or other factors.
Topically, guggul can cause allergic contact dermatitis (54464,54467).

Musculoskeletal ...There is one case of rhabdomyolysis reported in a patient who took guggul 300 mg three times daily. The patient developed hemoglobinuria within 2 weeks of starting guggul in addition to increased alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase, creatine kinase, and myoglobinemia. The patient did not have any muscular symptoms. The patient's condition improved when guggul was discontinued. The patient had a history of developing elevated creatine kinase levels after taking simvastatin; however, the patient was not taking a statin at the time of this episode of rhabdomyolysis (13029).

Neurologic/CNS ...Orally, guggul can cause headaches (3267,8155,8158,10371,42692,49583). Less commonly, guggul may cause restlessness and apprehension (49583,54492).

(Read more about GUGGUL)

General ...Orally, willow bark seems to be well tolerated.
Most Common Adverse Effects:
Orally: Diarrhea, dyspepsia, heartburn, and vomiting. May cause itching and rash in sensitive individuals.
Serious Adverse Effects (Rare):
Orally: Gastrointestinal bleeding and renal impairment. May cause serious allergic reactions, including anaphylaxis, in people who are allergic to aspirin.

Cardiovascular ...In one clinical trial, a single patient withdrew from the study investigating oral willow bark due to blood pressure instability that the authors determined was 'possibly' related to treatment (12804).

Dermatologic ...Orally, willow bark may cause itching and rash in some people due to allergy (6456,12474,12475,12804,86459).

Gastrointestinal ...Orally, willow bark extract can cause gastrointestinal adverse effects, but these appear to be less frequent than those caused by NSAIDs. Examples include diarrhea, heartburn, vomiting, and dyspepsia (12474,12475,12804,86459). In a case report of a child, severe gastrointestinal bleeding occurred following use of a specific syrup (FreddoBaby), which contained ribwort plantain, licorice, willow bark, black elder, meadowsweet, and propolis. The adverse effect was attributed to salicylate content of the syrup. This product has since been withdrawn from the market (86477).

Immunologic ...Orally, willow bark may cause serious allergic reactions, including anaphylaxis, in people who are allergic to aspirin (10392)

Neurologic/CNS ...Orally, willow bark may cause headache and dizziness (12804). In a clinical trial evaluating a combination product containing willow bark, black cohosh, sarsaparilla, poplar bark, and guaiac wood (Reumalex), severe headaches occurred (35946).

Ocular/Otic ...Orally, symptoms of allergy to willow bark have included swollen eyes (6456).

Renal ...Salicylates can inhibit prostaglandins, which can reduce renal blood flow (12805). Salicin can cause renal papillary necrosis (12806). The risk for toxicity is greater with high acute doses or chronic use (12805).

(Read more about WILLOW BARK)

General ...When used orally in high doses or long-term, yerba mate may be unsafe.
Most Common Adverse Effects:
Orally: Many of the adverse effects of yerba mate can be attributed to its caffeine content, such as diuresis, gastric irritation, insomnia, nausea, nervousness, restlessness, tachycardia, tachypnea, and tremors.
Serious Adverse Effects (Rare):
Orally: Cancer, hyperglycemia, ketosis, metabolic acidosis, sinus tachycardia. These adverse effects are more common with high doses or long-term use.

Cardiovascular ...Orally, yerba mate may cause cardiovascular-related adverse effects due to its caffeine content. High doses of mate providing 250 mg of caffeine can increase blood pressure. However, this doesn't seem to occur in people who habitually consume caffeine products (2722). Also, epidemiological research suggests that there is no association of caffeine consumption with incidence of hypertension (13739).
Due to its caffeine content, yerba mate may cause other adverse cardiovascular effects when used orally. These effects include tachycardia, quickened respiration, chest pain, premature heartbeat, arrhythmia, and hypertension (11832,11838,13735). Large doses of caffeine can also cause massive catecholamine release and subsequent sinus tachycardia (13734). There is also one report of venous occlusive disease associated with excessive, long-term mate consumption (5614).
Epidemiological research has found that regular caffeine intake of up to 400 mg per day, or approximately 8-10 cups of yerba mate, is not associated with an increased incidence of atrial fibrillation (38018,38076,91028,91034,97451,97453), atherosclerosis (38033), cardiac ectopy (91127), stroke (37804), ventricular arrhythmia (95948,97453), and cardiovascular disease in general (37805,98806).
Combining caffeine beverages such as yerba mate with ephedra may theoretically increase the risk of adverse cardiovascular events. There is one report of ischemic stroke in an athlete who consumed ephedra 40-60 mg, creatine monohydrate 6 grams, caffeine 400-600 mg, and a variety of other supplements daily for six weeks (1275).

Endocrine ...Yerba mate contains caffeine. Orally, large doses of caffeine can cause massive catecholamine release and subsequent metabolic acidosis, hyperglycemia, and ketosis (13734). Some evidence shows caffeine is associated with fibrocystic breast disease, breast cancer, and endometriosis in females. However, this is controversial since findings are conflicting (8043). Restricting caffeine in females with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain (8996). A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages 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, drinking yerba mate infusions has been associated with nausea and irritation of the stomach or oral mucosa in a small number of patients in one clinical study (86657). Yerba mate contains caffeine. Orally, caffeine can cause gastric irritation, nausea, and vomiting (11832,11838,13735). Caffeine-containing beverages can stimulate gastric secretion in humans, which may potentiate ulcer symptoms (36404). Some believe that long-term use of caffeine can cause withdrawal symptoms following discontinuation of use. However, the existence of caffeine withdrawal is controversial. Some researchers think that if it exists, it appears to be of little clinical significance (2723,11839). Gastrointestinal withdrawal symptoms such as nausea and vomiting have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects. Clinically significant gastrointestinal symptoms caused by caffeine withdrawal may be uncommon (2723,11839).

Hematologic ...Yerba mate contains caffeine. Orally, caffeine can cause hypokalemia (11832,11838,13735).

Immunologic ...Yerba mate contains caffeine. Orally, caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare (11315).

Musculoskeletal ...Yerba mate contains caffeine. Some epidemiological research suggests that caffeine may be associated with an increased risk of osteoporosis, but conflicting evidence exists. 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 per day, or approximately 8-10 cups of yerba mate, does not seem to significantly increase osteoporosis risk in most postmenopausal adults with normal calcium intake (2669,6025,10202,11317,98806).

Some researchers believe that stopping regular use of caffeine may cause withdrawal symptoms such as muscle tension and muscle pains. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839). However, there is a case of withdrawal in a premature neonate following chronic parental drinking of yerba mate (86618). Symptoms included hypertonia in the limbs and brisk tendon reflexes. The authors indicated that high concentrations of caffeine and theobromine were found in the placenta, cord serum, neonatal urine, parental and neonatal hair, meconium, and breast milk. Although symptoms progressively disappeared at 84 hours of age, irritability was still occasionally present at discharge (24 days of age).

Neurologic/CNS ...Orally, drinking yerba mate infusions has been associated with insomnia in a small number of patients in one clinical study (86657). Yerba mate contains caffeine. Orally, caffeine can cause insomnia, nervousness, headache, anxiety, agitation, jitteriness, restlessness, ringing in the ears, tremors, delirium, and convulsions (11832,11838,13735). Caffeine may also exacerbate sleep disturbances in patients with acquired immunodeficiency syndrome (AIDS) (10204).
There is some concern that stopping regular use of caffeine may cause withdrawal symptoms such as headache, tiredness and fatigue, decreased energy, alertness, and attentiveness, drowsiness, decreased contentedness, depressed mood, difficulty concentrating, irritability, and lack of clear-headedness are typical of caffeine withdrawal (13738). Other symptoms such as delirium, nervousness, restlessness, and anxiety have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839). However, there is a case of withdrawal in a premature neonate following chronic parental drinking of yerba mate (86618). Symptoms included jitteriness and irritability and a high-pitched cry. The authors indicated that high concentrations of caffeine and theobromine were found in the placenta, cord serum, neonatal urine, parental and neonatal hair, meconium, and breast milk. Although symptoms progressively disappeared at 84 hours of age, irritability was still occasionally present at discharge (24 days of age).

Oncologic ...Orally, the prolonged use of yerba mate or use of yerba mate in high doses (typically more than 1-2 liters daily) is associated with an increased risk of cancer, including mouth, esophageal, laryngeal, kidney, bladder, cervical, prostate, and lung cancer (1528,1529,1530,1531,11863,11864,92150,86595,86614,86700,86701). The effect seems to be cumulative and dose dependent. The risk of cancer with yerba mate use seems to increase if it is taken as a warm beverage. In 1991, the International Agency for Research on Cancer (IARC), reported that hot yerba mate drinking is a 2A agent, meaning it is probably carcinogenic for humans (92150). A statement published in 2016 stated there is no conclusive evidence for carcinogenicity when yerba mate is consumed at temperatures that are "not very hot" (95015). Drinking very hot beverages is believed to be a probable cause of esophageal cancer in humans (95015). Concomitant tobacco and alcohol use can increase risk 7-fold (11863).

Pulmonary/Respiratory ...Yerba mate contains caffeine. Orally, caffeine may cause tachypnea-induced respiratory alkalosis (11832,11838,13735). Some researchers think that stopping regular use of caffeine may cause withdrawal symptoms such as runny nose. However, this symptom may be from nonpharmacological factors related to knowledge and expectation of effects (2723,11839).

Renal ...Yerba mate contains caffeine. Orally, caffeine may cause diuresis (11832,11838,13735).

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