Hummer Pills by Light Years

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Allergic rhinitis (hay fever). Although there has been interest in using oral bitter orange for allergic rhinitis, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Androgenic alopecia. Although there has been interest in using topical bitter orange for androgenic alopecia, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Anxiety. It is unclear if oral bitter orange or aromatherapy with bitter orange is beneficial in patients with anxiety. Details: Aromatherapy with bitter orange has been evaluated for anxiety in hospitalized or recently hospitalized patients. A clinical study in conscious patients admitted to the intensive care unit shows that inhaling bitter orange as aromatherapy for 30 minutes is associated with lower anxiety scores immediately and 3 hours after the intervention, but not at 1 hour after, when compared with placebo. It is unclear if the improvement from baseline differed between groups; baseline anxiety scores were significantly higher in the placebo group (108752). Another clinical study in adults with acute coronary syndrome shows that aromatherapy with bitter orange essential oil 30% for the 2 days immediately after hospitalization improves anxiety scores by 19%, compared with a 6% improvement in those inhaling placebo (101710). Oral bitter orange has also been evaluated in patients with anxiety. A small clinical study in postmenopausal adults with moderate anxiety shows that taking dried bitter orange flower powder 500 mg orally twice daily for 8 weeks reduces anxiety symptoms by about 4% when compared with placebo, as measured on the State-Trait Anxiety Inventory Scale (97256). However, this improvement is not likely to be considered clinically significant.
• Athletic performance. Several small, short-term clinical studies suggest that oral bitter orange does not improve athletic performance, although some conflicting findings exist. Details: One small clinical study in young males who were former athletes shows that taking 100 mg of p-synephrine from bitter orange extract (Advantra Z, Nutratech Inc.), with or without caffeine 100 mg, daily for 4 days increases the number of total repetitions and volume load by 11% during resistance squat exercise performance when compared with placebo. However, there was no difference in ratings of perceived exertion, and only the p-synephrine plus caffeine group showed an increase in mean power and velocity measures (95683). Other small studies have failed to show a benefit, with or without caffeine. One small study of physically active males with habitual caffeine use shows that taking caffeine 100 mg and bitter orange 100 mg once before exercise does not affect peak power, mean power, total work, or perceived effort or fatigue when compared with placebo (101709). Another small clinical study shows that taking p-synephrine (Synephrine HCL 99%, Nutrition Power) 3 mg/kg orally 60 minutes before exercise does not improve jump tests, 60-meter sprints, or 100-meter sprints in healthy sprint athletes (95655). A small clinical study shows that taking a specific caffeine-containing pre-workout supplement (Cellucor C4 Pre-Workout, Nutrabolt) along with bitter orange extract (Nutratech Inc.) as a single dose 30 minutes before exercise does not improve athletic performance during anaerobic cycling or leg and bench press exercises (95657). Also, taking this combination daily for 8 weeks does not improve strength or body composition when compared with placebo (95656).
• Cancer. Although there has been interest in using oral bitter orange to prevent cancer, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Chronic kidney disease (CKD). Although there has been interest in using oral bitter orange for CKD and other kidney and bladder conditions, there is insufficient reliable information about the clinical effects of bitter orange for these conditions.
• Conjunctivitis. Although there has been interest in using topical bitter orange for conjunctivitis, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Constipation. Although there has been interest in using oral bitter orange for constipation, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Diabetes. Oral bitter orange has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A very small clinical study in patients with type 2 diabetes shows that drinking a tea made from the leaves of Indian snakeroot and the fruit of bitter orange for 4 months decreases fasting and postprandial glucose levels and glycated hemoglobin (HbA1c) levels when compared with placebo (35751). However, it is unclear if these effects are due to bitter orange, Indian snakeroot, or the combination.
• Diarrhea. Although there has been interest in using oral bitter orange for diarrhea, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Dyspepsia. It is unclear if oral bitter orange is beneficial in patients with dyspepsia. Details: One small clinical trial in patients with functional dyspepsia shows that taking a specific product containing bitter orange in combination with other ingredients (Zhizhu) three times daily for 4 weeks improves symptoms of functional dyspepsia in 67% of patients, compared with 45% of patients taking a similar product containing sweet orange instead of bitter orange (35757).
• Fatigue. Although there has been interest in using oral bitter orange for fatigue, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Flatulence. Although there has been interest in using oral bitter orange for flatulence, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Frostbite. Although there has been interest in using oral bitter orange to prevent frostbite, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Gallbladder disease. Although there has been interest in using oral bitter orange for gallbladder disease, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Headache. Although there has been interest in using topical bitter orange for headache, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Hyperlipidemia. Although there has been interest in using oral bitter orange for hyperlipidemia, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Insomnia. It is unclear if using bitter orange aromatherapy for sleep disturbances is beneficial in postmenopausal or pregnant adults. Details: A small clinical study in postmenopausal adults with sleep disturbances shows that inhaling essential oil of bitter orange 10% as aromatherapy for 5 minutes twice daily for 4 consecutive days each week for 4 weeks does not improve sleep quality when compared with odorless sweet almond oil (108642). Other clinical research in pregnant adults with sleep disturbances shows that inhaling bitter orange essential oil as aromatherapy for 20 minutes twice daily for 1 month improves sleep scores, including sleep duration, latency, and efficiency, when compared with sweet almond oil (110043).
• Obesity. It is unclear if oral bitter orange, or its constituent p-synephrine, is beneficial for obesity. Details: A meta-analysis of clinical trials in adults with or without obesity shows that taking p-synephrine, a constituent of bitter orange, 6-214 mg orally daily for up to 8 weeks does not reduce body weight or fat mass, or alter blood glucose levels, when compared with placebo (109950). Bitter orange has also been studied in combination with other ingredients. One small clinical trial in overweight adults shows that taking a combination of bitter orange 975 mg, caffeine 528 mg, and St. John's wort 900 mg daily along with calorie restriction and exercise reduces body weight when compared with caloric restriction and exercise alone (11268). Another small clinical study in overweight adults shows that taking a specific combination product (Prograde Metabolism, Prograde Nutrition) containing bitter orange, raspberry ketone, caffeine, capsaicin, garlic, ginger, black pepper, cayenne pepper, and chromium along with diet and exercise for 8 weeks reduces body weight, fat mass, and hip and waist girth and increases lean body mass and energy levels when compared with placebo (91291). However, a small clinical trial in overweight and obese adults shows that taking a different combination product (Charge, Labrada), containing bitter orange 150 mg, providing 9 mg synephrine, plus caffeine and several other ingredients twice daily for 8 weeks does not reduce body weight (15381). The effects of bitter orange alone on body weight are unclear.
• Pain (acute). It is unclear if aromatherapy with bitter orange essential oil is beneficial in hospitalized patients with pain. Details: One small clinical trial in conscious patients in intensive care units shows that aromatherapy with bitter orange essential oil for 30 minutes does not reduce pain when compared with placebo (104187).
• Peptic ulcers. Although there has been interest in using oral bitter orange for peptic ulcers, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Premenstrual syndrome (PMS). It is unclear if aromatherapy with bitter orange essential oil is beneficial in patients with PMS. Details: One small clinical trial in healthy female students with PMS shows that inhaling bitter orange blossom 0.5% essential oil as aromatherapy for 5 minutes twice daily for 5 days, starting about one week before menstruation and repeating for two menstrual cycles, improves psychological but not physical symptoms of PMS when compared with aromatherapy with odorless sweet almond oil (98331).
• Pre-procedural anxiety. It is unclear if oral bitter orange or aromatherapy with bitter orange is beneficial for reducing anxiety before surgery. Details: One small clinical study in patients undergoing minor operations shows that taking bitter orange blossom distillate 1 mL/kg two hours prior to surgery reduces preoperative anxiety when compared to baseline. No significant improvements in anxiety were reported in patients taking placebo before surgery (35759). Another small clinical study in patients undergoing coronary angiography shows that inhaling bitter orange essential oil for 15-20 minutes about one hour prior to the procedure reduces anxiety when compared with placebo (104186).
• Pressure ulcers. Although there has been interest in using topical bitter orange for pressure ulcers, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Rheumatoid arthritis (RA). Although there has been interest in using topical bitter orange for RA, there is insufficient reliable information about the clinical effects of bitter orange for this condition.
• Rhinosinusitis. Although there has been interest in using oral bitter orange for rhinosinusitis, there is insufficient reliable information about the clinical effects of bitter orange for this purpose.
• Sexual dysfunction. It is unclear if topical bitter orange oil is beneficial in postmenopausal adults with sexual dysfunction. Details: Preliminary clinical research in postmenopausal adults with sexual dysfunction shows that inhaling bitter orange essential oil 10% as aromatherapy for 5 minutes twice daily, 4 days per week for 4 weeks, improves sexual dysfunction scores by 58% when compared with almond oil. Patients reported improvements in the domains of desire, arousal, lubrication, orgasm, pain, and satisfaction (110042).
• Tinea corporis. It is unclear if topical bitter orange oil is beneficial in patients with tinea corporis. Details: In one small clinical study of patients with either tinea corporis, tina cruris, or tinea pedis, 80% of patients applying a bitter orange oil 25% emulsion three times daily experienced a cure within 1-2 weeks, and 20% experienced a cure within 2-3 weeks. For those applying a solution of bitter orange oil 20% in alcohol, 50% experienced a cure in 1-2 weeks, 30% in 2-3 weeks, and 20% in 3-4 weeks (6972). The validity of these findings is limited by the lack of a comparator group.
• Tinea cruris. It is unclear if topical bitter orange oil is beneficial in patients with tinea cruris. Details: In one small clinical study of patients with either tinea corporis, tina cruris, or tinea pedis, 80% of patients applying a bitter orange oil 25% emulsion three times daily experienced cure within 1-2 weeks, and 20% experienced a cure within 2-3 weeks. For those applying a solution of bitter orange oil 20% in alcohol, 50% experienced a cure in 1-2 weeks, 30% in 2-3 weeks, and 20% in 3-4 weeks (6972). The validity of these findings is limited by the lack of a comparator group.
• Tinea pedis. It is unclear if topical bitter orange oil is beneficial in patients with tinea pedis. Details: In one small clinical study of patients with either tinea corporis, tina cruris, or tinea pedis, 80% of patients applying a bitter orange oil 25% emulsion three times daily experienced cure within 1-2 weeks, and 20% experienced a cure within 2-3 weeks. For those applying a solution of bitter orange oil 20% in alcohol, 50% experienced a cure in 1-2 weeks, 30% in 2-3 weeks, and 20% in 3-4 weeks (6972). The validity of these findings is limited by the lack of a comparator group. More evidence is needed to rate bitter orange for these uses.

(Read more about BITTER ORANGE)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Age-related cognitive decline. Oral fo-ti has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in patients with mild age-related cognitive decline shows that taking a combination product containing fo-ti root and Panax ginseng as five capsules three times daily for 3 months improves memory when compared to baseline (50720). The validity of these findings is limited by a lack of placebo control group.
• Aging. Although there has been interest in using oral fo-ti for aging, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Alopecia areata. Although there has been interest in using oral fo-ti for alopecia areata, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Alzheimer disease. Although there has been interest in using oral fo-ti for Alzheimer disease, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Androgenic alopecia. Although there has been interest in using oral fo-ti for androgenic alopecia, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Cardiovascular disease (CVD). Although there has been interest in using oral fo-ti for CVD, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Dyslipidemia. Oral fo-ti has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: A small clinical study in adults in China with dyslipidemia shows that taking four capsules of a specific combination product (Blood Fat Droplets, Vita Green Pharmaceutical Ltd.), containing extracts of fo-ti 43 mg, hawthorn 129 mg, Asian water plantain 86 mg, corn silk 86 mg, reishi mushroom 43 mg, and white mulberry 43 mg, twice daily for 12 weeks decreases low-density lipoprotein (LDL) cholesterol by 12 mg/dL, or around 9%, but does not improve total cholesterol, high-density lipoprotein (HDL) cholesterol, or triglyceride levels, when compared with placebo (99854).
• Insomnia. Although there has been interest in using oral fo-ti for insomnia, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Osteoarthritis. Although there has been interest in using oral fo-ti for osteoarthritis, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Osteoporosis. Although there has been interest in using oral fo-ti for osteoporosis, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Parkinson disease. Although there has been interest in using oral fo-ti for Parkinson disease, there is insufficient reliable information about the clinical effects of fo-ti for this purpose.
• Wrinkled skin. Although there has been interest in using topical fo-ti for wrinkled skin, there is insufficient reliable information about the clinical effects of fo-ti for this purpose. More evidence is needed to rate fo-ti for these uses.

(Read more about FO-TI)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Anxiety. Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Preliminary clinical research shows that taking two tablets of a specific product (Euphytose) containing hawthorn, black horehound, passionflower, valerian, cola nut, and guarana three times daily for 28 days can reduce the severity of anxiety in a greater percentage of patients with adjustment disorder with anxious mood compared to placebo (6250). However, because guarana was included in the supplement as a mild stimulant, it is unclear if this component contributed to the antianxiety effect of the product.
• Athletic performance. Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: Clinical research shows that taking a single dose of a specific product (Berocca Boost, Bayer) containing guarana 222.2 mg (standardized to 40 mg caffeine), B vitamins, vitamin C, and minerals slightly improves exercise tolerance in trained individuals by approximately 2% when compared with placebo (91491). A small crossover study in young adult recreational handball players shows that taking a specific multi-ingredient supplement product (Olimp, Poland) containing guarana, caffeine, and other ingredients (total caffeine content 300 mg) prior to exercise slightly improves the time to complete agility testing but does not increase jump height when compared with placebo. However, taking a supplement containing only guarana and caffeine (total caffeine content 300 mg) does not improve agility or jump height (111577). It is unclear if the effects in these studies are due to guarana, other ingredients, or the combination.
• Cancer-related anorexia. It is unclear if oral guarana is beneficial for anorexia in patients with cancer. Details: A preliminary clinical study shows that taking guarana extract might improve appetite and reduce weight loss in some patients with cancer-related anorexia. Taking guarana extract (Pharmanostra) 50 mg twice daily for 4 weeks stabilized or increased weight in 55% of patients and stabilized or improved appetite in 89% of patients. However, only two patients achieved a weight gain of at least 5%, which was the minimum weight gain considered to be a positive response (91487).
• Cancer-related fatigue. It is unclear if oral guarana is beneficial for fatigue in patients with cancer. Details: Meta-analyses of small clinical studies in patients with solid tumors or breast cancer who are receiving chemotherapy or radiation therapy show that taking guarana 75-100 mg daily for 2-12 weeks does not improve cancer-related fatigue when compared with placebo (108016,111576). Additionally, a systematic review of clinical studies in patients with a variety of solid tumor types found no difference in cancer-related fatigue following at least 5 weeks of guarana consumption (108016). Most studies included in the meta-analysis and systematic review were low-quality, and all studies were conducted in Brazil. Higher quality studies in other geographic locations are needed to confirm these findings.
• Chemotherapy-related fatigue. It is unclear if oral guarana is beneficial for fatigue in patients receiving chemotherapy. Details: In patients with breast cancer, clinical research shows taking guarana extract 50 mg twice daily for 21 days improves fatigue in 52% to 66% of patients, compared with only 10% to 13% in the placebo group (91482). Other preliminary clinical research shows that taking guarana extract 37.5 mg twice daily for 3 weeks improves or stabilizes fatigue in 90% of patients with chemotherapy-related fatigue when compared with baseline. However, when compared with placebo for an additional 3 weeks, guarana does not affect fatigue (91483). Other clinical research shows that taking a dried, purified extract of guarana (PC-18) in doses of 7.5, 12.5, or 37.5 mg twice daily for 21 days improves fatigue in patients with breast cancer when compared with baseline, but not when compared with placebo. It is possible that the magnesium silicate used as a filler in both active and placebo treatments in this study contributed a fatigue-reducing effect (99049).
• Chronic fatigue syndrome (CFS). Although there has been interest in using oral guarana for CFS, there is insufficient reliable information about the clinical effects of guarana for this condition.
• Cognitive function. It is unclear if oral guarana is beneficial for improving cognitive function. Details: In healthy individuals, some clinical research shows that taking a single dose of guarana dry extract 37.5-75 mg, containing 11% to 12% caffeine, improves the speed of cognitive task performance and memory for up to 6 hours, but does not improve reaction time or speed and accuracy of memory, when compared with placebo. Higher doses of guarana 150-300 mg do not appear to be effective (54374,91484). However, a small clinical study in young adult cyclists shows that taking guarana powder 125 mg/kg 30 minutes prior to cognitive testing improves reaction time and alertness scores when compared with placebo, but not when compared with caffeine (111361). Other clinical research shows that taking guarana powder 500 mg, containing 2.1% to 2.5% caffeine, twice daily for 3-150 days does not improve cognitive function when compared with placebo in adults or elderly individuals (54402,54414). Some research has evaluated guarana in combination with other ingredients. Preliminary clinical studies show that taking a specific product containing guarana 222 mg, B vitamins, vitamin C, and minerals (Berocca Boost, Bayer) can improve the speed and accuracy of visual information processing, working memory, and attention, as well as decrease mental fatigue, when compared to placebo (91485,91489,91491). Another specific combination product containing guarana 300 mg and other ingredients (Isoxan Actiflash, Menarini, NHS) improves reaction time by almost 600 msec for up to 90 minutes when compared with placebo or caffeine alone (91488). Conversely, a small clinical study in experienced young-adult video gamers shows that taking guarana 500 mg in combination with microalgae extract 440-880 mg daily for 30 days does not improve most measures of accuracy, reaction time, or gaming performance when compared to baseline (111360). A meta-analysis of 8 small clinical studies in healthy adults, that includes many of these studies, shows that taking a single dose of guarana 37.5-500 mg (median dose 222 mg; caffeine content 4-100 mg), alone or with other ingredients (i.e., B vitamins, vitamin C), within 360 minutes before a cognitive task does not improve overall cognitive performance or accuracy, but modestly improves reaction time when compared with placebo. In addition, cognitive performance was not related to guarana dose (111359). The validity of this analysis is limited by the heterogeneity of the included studies which utilized widely varying doses and various cognitive tests.
• Dysmenorrhea. Although there has been interest in using oral guarana for dysmenorrhea, there is insufficient reliable information about the clinical effects of guarana for this condition.
• Dyspepsia. Although there has been interest in using oral guarana for dyspepsia, there is insufficient reliable information about the clinical effects of guarana for this purpose.
• Erectile dysfunction (ED). Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: In middle-aged patients with ED, preliminary clinical research shows that taking two capsules of a specific combination product (Revactin, MD Concepts LLC) containing guarana 125 mg, muira puama 125 mg, ginger root 125 mg, and L-citrulline 400 mg twice daily for 3 months improves scores related to erectile function and intercourse satisfaction, but not sexual desire or orgasmic function, when compared to baseline (103224). The validity of this study is limited by the lack of a placebo control, the use of per-protocol analysis, and a high dropout rate. In fact, 44% of patients withdrew in order to resume use of phosphodiesterase type 5 (PDE5) inhibitors. Further, it is unclear if these effects are due to guarana, other ingredients, or the combination.
• Fatigue. Although there has been interest in using oral guarana for fatigue, there is insufficient reliable information about the clinical effects of guarana for this purpose.
• Headache. Although there has been interest in using oral guarana for headache, there is insufficient reliable information about the clinical effects of guarana for this purpose.
• Obesity. Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear. Details: One very small exploratory clinical study in overweight females shows that taking guarana 855 mg, yerba mate 1008 mg, and damiana 325 mg in divided doses daily for up to 45 days delays gastric emptying, increases satiety, and modestly improves weight loss when compared to baseline (11866). The validity of these findings is limited by the small study size and lack of a comparator group.
• Psychological well-being. It is unclear if oral guarana is beneficial for improving feelings of well-being. Details: Preliminary clinical research shows that taking guarana 1080 mg daily after breakfast for 5 days does not improve feelings of well-being or mood in healthy individuals (91490).
• Radiation-induced fatigue. It is unclear if oral guarana is beneficial for improving fatigue related to radiation therapy. Details: A small clinical trial shows that taking guarana 75 mg daily does not improve symptoms of depression or fatigue when compared with placebo in patients with breast cancer undergoing radiation therapy treatments (91481).

(Read more about GUARANA)

INSUFFICIENT RELIABLE EVIDENCE to RATE

• Hereditary hemorrhagic telangiectasia (HHT). It is unclear if topical rose geranium oil is beneficial for epistaxis in patients with HHT. Details: A small clinical study in patients with HHT shows that applying 3-4 drops of a topical formulation containing rose geranium essential oil 0.17% in sesame oil into the nose twice daily for at least 3 months reduces the severity of epistaxis by 34% when compared to baseline (93881). The validity of this finding is limited by a lack of control group.
• Neuropathic pain. Although there has been interest in using oral and topical rose geranium oil for neuropathic pain, there is insufficient reliable information about the clinical effects of rose geranium oil for this purpose.
• Postherpetic neuralgia. It is unclear if topical rose geranium oil is beneficial in patients with postherpetic neuralgia. Details: A small clinical study in patients with postherpetic neuralgia shows that a single topical application of rose geranium oil 50% or 100% can significantly reduce pain when compared with placebo. Pain relief appears to be concentration-dependent. Rose geranium oil in a concentration of 100% appears to be about twice as effective as a 50% concentration (16653).
• Wound healing. Although there has been interest in using topical rose geranium oil for wound healing, there is insufficient reliable information about the clinical effects of rose geranium oil for this purpose. More evidence is needed to rate rose geranium oil for these uses.

(Read more about ROSE GERANIUM OIL)

LIKELY SAFE ...when used orally in amounts commonly found in foods. Bitter orange has Generally Recognized as Safe (GRAS) status in the US (4912,35751).

POSSIBLY SAFE ...when bitter orange essential oil is used topically or by inhalation as aromatherapy (6972,7107,98331,104186,104187,108642).

POSSIBLY UNSAFE ...when used orally for medicinal purposes. Although single doses of synephrine, or low daily doses used short-term, may be safe in healthy adults (2040,11269,15381,35757,35759,91681,97256,98332), laboratory analyses raise concerns that many marketed bitter orange products contain higher amounts of synephrine and other natural and synthetic amines than on the label, increasing the risk for serious stimulant-related adverse effects (104185). Additionally, there is a lack of agreement regarding a safe daily dose of synephrine. Health Canada has approved 50 mg of p-synephrine daily when used alone, or 40 mg of p-synephrine in combination with up to 320 mg of caffeine daily in healthy adults (91684). The Federal Institute for Risk Assessment in Germany recommends that supplements should provide no more than 6.7 mg of synephrine daily. This recommendation is meant to ensure that patients who frequently consume synephrine in conventional foods will receive no more than 25.7 mg daily (91290). These limits are intended to reduce the risk for serious adverse effects. There have been several case reports of ischemic stroke and cardiotoxicity including tachyarrhythmia, cardiac arrest, syncope, angina, myocardial infarction, ventricular arrhythmia, and death in otherwise healthy patients who have taken bitter orange extract alone or in combination with other stimulants such as caffeine (2040,6979,12030,13039,13067,14326,14342,91680).

PREGNANCY AND LACTATION: LIKELY SAFE
when used orally in the amounts found in foods. Bitter orange has Generally Recognized as Safe (GRAS) status in the US (4912).

PREGNANCY AND LACTATION: POSSIBLY UNSAFE
when used orally for medicinal purposes. There are case reports of cardiotoxicity including tachyarrhythmia, syncope, and myocardial infarction in otherwise healthy adults who have taken bitter orange extract alone or in combination with other stimulants such as caffeine (2040,6979,12030,13039,13067,14326,14342,91680). The effects of bitter orange during lactation are unknown; avoid use.

(Read more about BITTER ORANGE)

POSSIBLY UNSAFE ...when used orally. Fo-ti has been linked to several cases of liver damage (7626,7627,14327,14347,14482,16459,17192,50711,50727,50729) (92892,92895,112231).

CHILDREN: POSSIBLY UNSAFE
when used orally. Fo-ti has been linked to several cases of liver damage in adults and at least one case in a 5-year-old child (14339,92895).

PREGNANCY: POSSIBLY UNSAFE
when used orally. Fo-ti contains anthraquinone constituents, which can exert a stimulant laxative effect. Bulk-forming or emollient laxatives are preferred in pregnancy (272). Fo-ti has also been linked to several cases of liver damage (7626,7627,14327). There is insufficient reliable information available about the safety of fo-ti when used topically during pregnancy.

LACTATION: POSSIBLY UNSAFE
when used orally. Anthraquinone constituents can cross into breast milk and might cause loose stools in some breast-fed infants (272). Fo-ti has also been linked to several cases of liver damage (7626,7627,14327). There is insufficient reliable information available about the safety of fo-ti when used topically during lactation.

(Read more about FO-TI)

LIKELY SAFE ...when consumed in amounts typically found in foods. Guarana has Generally Recognized as Safe (GRAS) status for use in foods in the US (4912).

POSSIBLY SAFE ...when used orally and appropriately, short-term (12). Guarana contains caffeine. 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).

POSSIBLY UNSAFE ...when used orally long-term or in high doses. Guarana contains a significant amount of caffeine. Chronic use, especially in large amounts, can produce tolerance, habituation, psychological dependence, and other significant adverse effects. Acute use of high doses, typically above 400 mg per day, has been associated with significant adverse effects such as tachyarrhythmias and sleep disturbances (11832,95503,98806). These effects would not be expected to occur with the consumption of decaffeinated guarana.

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 per kilogram). Serious toxicity can occur at lower doses depending on variables in caffeine sensitivity such as smoking, age, or prior caffeine use (11832,54425).

PREGNANCY: POSSIBLY SAFE
when consumed in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored during pregnancy to ensure moderate consumption. Although it is not considered a teratogen, caffeine crosses the placenta and causes dose-dependent increases in fetal blood concentrations (4260). The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects (2708,2709,2710,2711,9606,11733,16014,16015,98806). In some studies, consuming amounts over 200 mg daily is associated with a significantly increased risk of miscarriage (16014). This increased risk may be most likely to occur in individuals 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, caffeine can be safely consumed 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). However, some research has also found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years (109846). Advise individuals to keep caffeine consumption below 300 mg daily during pregnancy.

PREGNANCY: POSSIBLY UNSAFE
when used orally in amounts over 300 mg daily. Although it is not considered a teratogen, caffeine crosses the placenta and causes dose-dependent increases in fetal blood concentrations (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 keeping caffeine consumption from all sources below 300 mg daily. High maternal 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).

LACTATION: POSSIBLY SAFE
when used orally in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored when breast-feeding. Breast milk concentrations of caffeine are thought to be approximately 50% of serum concentrations (9892).

LACTATION: POSSIBLY UNSAFE
when used orally in large amounts. Consumption of guarana might cause irritability and increased bowel activity in nursing infants (6026). Large doses or excessive intake of guarana should be avoided when breast-feeding.

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LIKELY SAFE ...when used orally in amounts commonly found in foods. Rose geranium oil has Generally Recognized as Safe (GRAS) status in the US (4912).

POSSIBLY SAFE ...when used topically and appropriately, short-term. A single application of rose geranium oil in concentrations up to 100% has been safely used in a clinical trial (16653). ...when used intranasally and appropriately, short-term. Rose geranium oil has been applied with sesame oil in the nose safely (93881). There is insufficient reliable information available about using rose geranium oil orally for medicinal purposes.

PREGNANCY AND LACTATION:
Insufficient reliable information available; avoid amounts greater than those found in foods.

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, bitter orange might increase the risk of hypoglycemia when taken with antidiabetes drugs.  Details Some clinical research shows that drinking a tea containing bitter orange and Indian snakeroot reduces fasting and postprandial glucose levels in patients with type 2 diabetes who are using antidiabetes drugs (35751). However, it is unclear if these effects are due to bitter orange, Indian snakeroot, or the combination. An animal study also shows that p-synephrine in combination with gliclazide , a sulfonylurea, causes an additional 20% to 44% decrease in glucose levels when compared with gliclazide alone (95658).

CAFFEINE Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = B Bitter orange might increase blood pressure and heart rate when taken with caffeine.  Details Small clinical studies show that taking bitter orange in combination with caffeine can increase blood pressure and heart rate in otherwise healthy normotensive adults (13657,95659). Theoretically, this might increase the risk of serious cardiovascular adverse effects.

COLCHICINE Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Bitter orange might affect colchicine levels.  Details Colchicine is a substrate of P-glycoprotein and cytochrome P450 3A4 (CYP3A4). Bitter orange has been reported to inhibit CYP3A4 and increase levels of CYP3A4 substrates (7029,11362,93470). However, one small clinical study in healthy adults shows that drinking bitter orange juice 240 mL twice daily for 4 days and taking a single dose of colchicine 0.6 mg on the 4th day decreases colchicine peak serum levels by 24%, time to peak serum level by 1 hour, and overall exposure to colchicine by 20% (35762). The clinical significance of this finding is unclear.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = D Theoretically, bitter orange might increase levels of drug metabolized by CYP2D6.  Details In vitro research shows that octopamine, a constituent of bitter orange, weakly inhibits CYP2D6 enzymes (91878). This effect has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Bitter orange might increase levels of drugs metabolized by CYP3A4.  Details Small clinical studies suggest that single or multiple doses of freshly squeezed bitter orange juice 200-240 mL can inhibit CYP3A4 metabolism of drugs (7029,11362,93470), causing increased drug levels and potentially increasing the risk of adverse effects. However, the extent of the effect of bitter orange on CYP3A4-mediated drug interactions is unknown. Some evidence suggests that bitter orange selectively inhibits intestinal CYP3A4, but not hepatic CYP3A4. Its effect on P-glycoprotein, which strongly overlaps with CYP3A4 interactions, is unclear (7029,11269,11270,11362). One small clinical study shows that drinking 8 ounces of freshly squeezed bitter orange juice has no effect on cyclosporine, which seems to be more dependent on hepatic CYP3A4 and P-glycoprotein than intestinal CYP3A4 (11270).

DEXTROMETHORPHAN (Robitussin DM, others) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Bitter orange might increase blood levels of dextromethorphan.  Details One small clinical study shows that bitter orange juice increases dextromethorphan levels, likely through cytochrome P450 3A4 (CYP3A4) inhibition (11362). Theoretically, bitter orange might increase the risk for dextromethorphan-related adverse effects.

FELODIPINE (Plendil) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Bitter orange might increase blood levels of felodipine.  Details One small clinical study shows that bitter orange juice increases felodipine levels, likely through cytochrome P450 3A4 (CYP3A4) inhibition (7029). Theoretically, bitter orange might increase the risk for felodipine-related adverse effects.

INDINAVIR (Crixivan) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Bitter orange might increase blood levels of indinavir.  Details One small clinical study shows that bitter orange juice slightly increases indinavir levels, but this effect is likely to be clinically insignificant. Bitter orange selectively inhibits intestinal cytochrome P450 3A4 (CYP3A4); however, the metabolism of indinavir seems to be more dependent on hepatic CYP3A4 (11269). The effect of bitter orange on other protease inhibitors has not been studied.

MIDAZOLAM (Versed) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = B Bitter orange might increase blood levels of midazolam.  Details One small clinical study shows that bitter orange juice can increase midazolam levels, likely through inhibition of cytochrome P450 3A4 (CYP3A4) (7029). Theoretically, bitter orange might increase the risk of midazolam-related adverse effects.

MONOAMINE OXIDASE INHIBITORS (MAOIs) Interaction Rating = Major Do not take this combination. Severity = High •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking MAOIs with synephrine-containing bitter orange preparations might increase the hypertensive effects of synephrine, potentially leading to hypertensive crisis.  Details Bitter orange contains tyramine, octopamine, and synephrine, which are MAO substrates (11267,11995,12378).

QT INTERVAL-PROLONGING DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, bitter orange might have an additive effect when combined with drugs that prolong the QT interval, potentially increasing the risk of ventricular arrhythmias.  Details One case report suggests that taking bitter orange in combination with other stimulants such as caffeine might prolong the QT interval in some patients (13039).

SILDENAFIL (Viagra) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = B Bitter orange juice might increase blood levels of sildenafil.  Details A small clinical study in healthy adult males shows that drinking freshly squeezed bitter orange juice 250 mL daily for 3 days and taking a single dose of sildenafil 50 mg on the 3rd day increases the peak plasma concentration of sildenafil by 18% and the overall exposure to sildenafil by 44%. Theoretically, this may be due to inhibition of cytochrome P450 3A4 by bitter orange (93470).

STIMULANT DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, bitter orange might increase the risk of hypertension and adverse cardiovascular effects when taken with stimulant drugs.  Details Bitter orange appears to have stimulant effects (2040,6979).

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ANTIDIABETES DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the risk of hypoglycemia when taken with antidiabetes drugs.  Details Fo-ti reportedly has hypoglycemic effects (5,19).

CONTRACEPTIVE DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking large amounts of fo-ti might interfere with contraceptive drugs due to competition for estrogen receptors.  Details In vitro research suggests that fo-ti extract has estrogenic activity (10143,16061,50710).

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase or decrease the levels and clinical effects of drugs metabolized by CYP1A2.  Details In vitro research suggests that fo-ti might inhibit CYP1A2 (12479,112351). Additionally, in vitro research suggests that the degree of CYP1A2 inhibition depends on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts) (112351). However, in an animal study, an aqueous extract of fo-ti inhibited CYP1A2 while an alcoholic extract of fo-ti induced CYP1A2 (92898). Induction or inhibition of CYP1A2 by fo-ti has not been reported in humans.

CYTOCHROME P450 2B6 (CYP2B6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the levels and clinical effects of drugs metabolized by CYP2B6.  Details Animal research suggests that fo-ti might inhibit CYP2B6 (92898). One in vitro study suggests that the degree of CYP2B6 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts) (112351). However, this interaction has not been reported in humans.

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2C19.  Details Animal and in vitro research suggests that fo-ti may inhibit CYP2C19 (12479,92898,112351). An in vitro study suggests that the degree of CYP2C19 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts) (112351). However, this interaction has not been reported in humans.

CYTOCHROME P450 2C8 (CYP2C8) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the levels and clinical effects of drugs metabolized by CYP2C8.  Details In vitro research suggests that fo-ti might inhibit CYP2C8 (112351). However, this interaction has not been reported in humans.

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2C9.  Details Animal and in vitro research suggests that fo-ti may inhibit CYP2C9 (12479,92898,112351). However, this interaction has not been reported in humans.

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti may increase the levels and clinical effects of drugs metabolized by CYP2D6.  Details Animal research suggests that fo-ti might inhibit CYP2D6 (92898). Additionally, an in vitro study suggests that the degree of CYP2D6 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts) (112351). However, this interaction has not been reported in humans.

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the levels and clinical effects of drugs metabolized by CYP3A4.  Details In vitro research suggests that fo-ti might inhibit CYP3A4 (12479,112351). One in vitro study suggests that the degree of CYP3A4 inhibition may depend on the type of fo-ti extract (i.e., the raw plant leads to greater inhibition than extensively processed extracts) (112351). However, this evidence conflicts with animal research suggesting that fo-ti does not inhibit CYP3A4 (92898). This interaction has not been reported in humans.

DIGOXIN (Lanoxin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti, particularly raw fo-ti root, might increase the risk of hypokalemia and cardiotoxicity when taken with digoxin.  Details Raw fo-ti root contains anthraquinone derivatives, which might have stimulant laxative effects (5,16459). In vitro research shows that fermented and processed fo-ti root have reduced laxative effects compared with raw fo-ti root (99855).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti, particularly raw fo-ti root, might increase the risk of hypokalemia when taken with diuretic drugs.  Details Raw fo-ti root contains anthraquinone derivatives, which might have stimulant laxative effects and compound diuretic-induced potassium loss (5,16459). In vitro research shows that fermented and processed fo-ti root have reduced laxative effects compared with raw fo-ti root (99855).

ESTROGENS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, taking large amounts of fo-ti might interfere with hormone replacement therapy through competition for estrogen receptors.  Details In vitro research suggests that fo-ti extract has estrogenic activity (10143,16061,50710).

HEPATOTOXIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the risk of liver damage when taken with hepatotoxic drugs.  Details Fo-ti has been linked to liver damage in many reports (7626,7627,14327,14339,14347,14482,16459,17192,50711,50727,50729,92892,92895).

STIMULANT LAXATIVES Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti, particularly raw fo-ti root, might increase the risk of fluid and electrolyte depletion when taken with stimulant laxatives.  Details Raw fo-ti root contains anthraquinone derivatives, which might have stimulant laxative effects (5,16459). However, in vitro research shows that fermented and processed fo-ti root have reduced laxative effects compared with raw fo-ti root (99855).

SULINDAC (Clinoril) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase or decrease the levels and clinical effects of sulindac.  Details Animal research suggests that the type of fo-ti extract might affect the levels of sulindac differently; the raw plant may increase levels, but processed parts may decrease levels (112351). Induction or inhibition of CYP1A2 by fo-ti has not been reported in humans.

WARFARIN (Coumadin) Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, fo-ti might increase the effects and adverse effects of warfarin.  Details Fo-ti may have stimulant laxative effects and cause diarrhea, especially when the raw or unprocessed fo-ti root is used (5,12,16459,50733,99855). Diarrhea can increase the effects of warfarin, increase international normalized ratio (INR), and increase the risk of bleeding. Also, fo-ti has been linked to cases of acute liver failure which can decrease clotting factor production and increase the effects of warfarin. In one case, a patient who had been stable on warfarin presented with acute hepatitis and an INR elevated to 14.98. The patient had been taking fo-ti for 90 days prior to admission. Discontinuation of warfarin and fo-ti lead to a decrease in the INR and full recovery (17192).

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ADENOSINE (Adenocard) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, guarana might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.  Details Guarana contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine (11771). It is recommended that methylxanthines 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, alcohol might increase the levels and adverse effects of caffeine.  Details Guarana contains caffeine. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism (6370).

ANTICOAGULANT/ANTIPLATELET DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = High •  Occurrence = Possible •  Level of Evidence = D Theoretically, guarana may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.  Details In vitro and animal research suggests that guarana extract can inhibit platelet aggregation (54378,54388,54435). This effect may be due to the caffeine in guarana, which is also reported to have antiplatelet activity (8028,8029). 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 guarana with antidiabetes drugs might interfere with blood glucose control.  Details Some conflicting reports claim that caffeine, a constituent of guarana, might increase or decrease blood sugar (6024,8646).

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

CARBAMAZEPINE (Tegretol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, guarana 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 given to animals 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 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, concomitant use might increase the effects and adverse effects of caffeine in guarana.  Details Guarana contains caffeine. 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 Theoretically, guarana might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.  Details Guarana contains caffeine. Caffeine can 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). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to the 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, concomitant use might increase the effects and adverse effects of caffeine found in guarana.  Details Guarana contains caffeine. Oral contraceptives 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 might increase the levels and adverse effects of caffeine.  Details Guarana contains caffeine. Caffeine is metabolized by the CYP1A2 enzyme. 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, guarana might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.  Details Guarana contains caffeine. Caffeine might inhibit 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 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 risk of adverse effects from caffeine.  Details In human research, disulfiram decreases the clearance and increases the half-life of caffeine (11840).

DIURETIC DRUGS Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, using guarana with diuretic drugs might increase the risk of hypokalemia.  Details Guarana 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 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 Guarana contains caffeine. 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 Guarana contains caffeine. Estrogen inhibits caffeine metabolism (2714).

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

FELBAMATE (Felbatol) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, guarana might reduce the effects of felbamate and increase the risk for convulsions.  Details Guarana contains caffeine. Animal research shows that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate (23563). This effect has not been observed 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 Guarana contains caffeine. 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, guarana might increase the levels and adverse effects of flutamide.  Details Guarana contains caffeine. In vitro evidence shows 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 Guarana contains caffeine. Fluvoxamine reduces caffeine metabolism (6370).

LITHIUM Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Probable •  Level of Evidence = D Theoretically, abrupt guarana withdrawal might increase the levels and adverse effects of lithium.  Details Guarana contains caffeine. Theoretically, abrupt caffeine withdrawal might increase serum lithium levels. 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 caffeine.  Details Guarana contains caffeine. Animal research shows 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 Guarana contains caffeine. Methoxsalen can reduce 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 Guarana contains caffeine. Mexiletine can decrease caffeine elimination by 50% (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 Guarana contains caffeine. Caffeine has been shown to inhibit 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, concomitant use might increase the risk of hypertension.  Details Guarana contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly (36549).

PENTOBARBITAL (Nembutal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = B Theoretically, guarana might decrease the effects of pentobarbital.  Details Guarana contains caffeine. In vivo evidence suggests that caffeine can negate the hypnotic effects of pentobarbital in humans (13742). However, animal research suggests that guarana does not alter the hypnotic effect of pentobarbital (54419).

PHENOBARBITAL (Luminal) Interaction Rating = Moderate Be cautious with this combination. Severity = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, guarana might reduce the effects of phenobarbital and increase the risk for convulsions.  Details Guarana contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of phenobarbital (23558,23559,23561). 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 Guarana contains caffeine. Phenothiazines 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 Guarana 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 = Moderate •  Occurrence = Possible •  Level of Evidence = D Theoretically, guarana might reduce the effects of phenytoin and increase the risk for convulsions.  Details Guarana contains caffeine. Animal research shows 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, guarana might increase the levels and clinical effects of pioglitazone.  Details Guarana 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 = Minor Be watchful with this combination. Severity = Mild •  Occurrence = Possible •  Level of Evidence = B Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.  Details Guarana contains caffeine. Theoretically, concomitant use might increase serum caffeine concentrations and the risk of adverse effects. Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting the cytochrome P450 1A2 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 Guarana 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 = Possible •  Level of Evidence = D Theoretically, concomitant use might increase stimulant adverse effects.  Details Guarana contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects (11832).

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

THEOPHYLLINE Interaction Rating = Moderate Be cautious with this combination. Severity = Mild •  Occurrence = Probable •  Level of Evidence = D Theoretically, guarana might increase the levels and adverse effects of theophylline.  Details Guarana contains caffeine. Large amounts of caffeine might decrease 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, guarana might increase the levels and adverse effects of tiagabine.  Details Guarana contains caffeine. Animal research shows 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 Guarana contains caffeine. In vitro evidence shows that ticlopidine can inhibit the metabolism of caffeine (23557). However, this interaction has not been reported in humans.

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

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General ...Orally, bitter orange might be unsafe when used in medicinal amounts. Topically and when inhaled as aromatherapy, bitter orange seems to be well tolerated.
Most Common Adverse Effects:
Orally: Hypertension and tachycardia, particularly when used in combination with caffeine and/or other stimulant ingredients.
Topically: Skin irritation.
Serious Adverse Effects (Rare):
Orally: Myocardial infarction, QT prolongation, seizures, stroke, syncope, tachyarrhythmia, and ventricular fibrillation have been reported in patients taking bitter orange in combination with other ingredients. It is unclear if these effects are due to bitter orange, other ingredients, or the combination.

Cardiovascular ...Bitter orange, which contains adrenergic agonists synephrine and octopamine, may cause hypertension and cardiovascular toxicity when taken orally (2040,6969,6979). Studies evaluating the effect of bitter orange on cardiovascular parameters have been mixed. Several studies show that taking bitter orange alone or in combination with caffeine increases blood pressure and heart rate. In one clinical study, bitter orange in combination with caffeine increased systolic and diastolic blood pressure and heart rate in otherwise healthy normotensive adults (13657). In another study, a single dose of bitter orange 900 mg, standardized to 6% synephrine (54 mg), also increased systolic and diastolic blood pressure and heart rate for up to 5 hours in young, healthy adults (13774). Using half that dose of bitter orange and providing half as much synephrine, did not seem to significantly increase blood pressure or QT interval in healthy adults (14311). Increased diastolic, but not systolic, blood pressure or heart rate also occurred in a clinical trial involving a specific supplement containing synephrine 21 mg and caffeine 304 mg (Ripped Fuel Extreme Cut, Twinlab) (35743). Synephrine given intravenously to males increased systolic blood pressure, but lacked an effect on diastolic blood pressure or heart rate (12193).
In clinical research and case reports, tachycardia, tachyarrhythmia, QT prolongation, ischemic stroke, variant angina, and myocardial infarction have occurred with use of bitter orange or synephrine-containing multi-ingredient products (12030,13039,13067,13091,13657,14326,35749,91680). In one case report, a combination product containing bitter orange may have masked bradycardia and hypotension while exacerbating weight loss in a 16 year-old female with an eating disorder taking the product for weight loss (35740). From 1998 to 2004, Health Canada received 16 reports of serious adverse cardiovascular reactions such as tachycardia, cardiac arrest, ventricular fibrillation, blackout, and collapse. In two of these cases, the patient died. In almost all of these cases, bitter orange was combined with another stimulant such as caffeine, ephedrine, or both (14342).
Other research has found no significant effect of bitter orange on blood pressure or heart rate. Several clinical studies have reported that, when taken as a single dose or in divided doses ranging from 20-100 mg for one day, p-synephrine had no significant effect on blood pressure, heart rate, electrocardiogram results or adverse cardiovascular events in healthy adults (35772,91681,91681,95659,101708) Similarly, no difference in blood pressure, heart rate or electrocardiogram results were reported when p-synephrine from bitter orange (Advantra Z/Kinetic; Nutratech/Novel Ingredients Inc.) was taken for 6 weeks in healthy patients (11268). Another clinical study showed no significant effect of bitter orange (Nutratech Inc.), standardized to synephrine 20 mg, on blood pressure or heart rate when taken daily for 8 weeks in healthy males (95656). In other research, changes in blood pressure, heart rate, or QTc interval were lacking when bitter orange was given alone or in combination with caffeine and green tea (14311,35753,35755,35764,35769,35770). In one study of healthy adults, taking a single dose of p-synephrine 103 mg actually reduced mean diastolic blood pressure by 0.4-4 mmHg at 1 and 2 hours after administration when compared with placebo (95659).
A meta-analysis of clinical trials in adults with or without obesity suggests that taking p-synephrine 6-214 mg orally daily does not affect blood pressure or heart rate when used short-term, but modestly increases blood pressure and heart rate when taken for 56-60 days (109950).
The effect of bitter orange on blood pressure, heart rate, and electrocardiogram results in patients with underlying conditions, particularly cardiovascular disease, is unknown and requires further study.

Dermatologic ...Photosensitivity may occur, particularly in fair-skinned people (11909). In a clinical trial, topical application with bitter orange essential oil resulted in irritation (6972).

Endocrine ...Some clinical research shows that taking a specific supplement containing 21 mg of synephrine and 304 mg of caffeine (Ripped Fuel Extreme Cut, Twinlab) increases levels of postprandial glucose (35743). Other preliminary clinical research shows that taking a specific pre-workout supplement (Cellucor C4 Pre-Workout, Nutrabolt) along with a bitter orange extract standardized for synephrine 20 mg (Nutratech Inc.) 30 minutes once before exercise causes a significant 12% increase in glucose (95657); however, there is no difference in blood glucose when compared with placebo when this combination is taken daily for 8 weeks (95656). The effect of bitter orange itself is unclear.

Gastrointestinal ...Bitter orange has been linked to a report of ischemic colitis. In one case, a 52-year-old female developed ischemic colitis after taking a bitter orange-containing supplement (NaturalMax Skinny Fast, Nutraceutical Corporation) for a week. Symptoms resolved within 48 hours after discontinuing the supplement (15186). As this product contains various ingredients, the effect of bitter orange itself is unclear.

Musculoskeletal ...Unsteady gait has been noted in one case report of a patient taking bitter orange (13091). In another case, an otherwise healthy, Black male with sickle cell trait, developed severe rhabdomyolysis following ingestion of a specific weight loss product (Lipo 6, Nutrex Research Inc.), which contained synephrine and caffeine (16054). However, other preliminary clinical research shows that taking a specific pre-workout supplement (Cellucor C4 Pre-Workout, Nutrabolt) along with a bitter orange extract standardized for synephrine 20 mg (Nutratech Inc.), taken 30 minutes once before exercise (95657) or daily for 8 weeks, does not affect creatine kinase or serum creatinine levels when compared with placebo (95656). As these products contain various ingredients, the effect of bitter orange itself is unclear.

Neurologic/CNS ...Dizziness, difficulty in concentrating, memory loss, syncope, seizure, and stroke have been noted in case reports following bitter orange administration (13091,13039). Theoretically, bitter orange may trigger a migraine or cluster headache due to its synephrine and octopamine content (35768). When used as aromatherapy, bitter orange essential oil has also been reported to cause headache in some patients (104187). Sprint athletes taking the bitter orange constituent p-synephrine 3 mg/kg (Synephrine HCL 99%, Nutrition Power) 60 minutes before exercises and sprinting reported more nervousness (mean difference 0.9) when compared with placebo on a Likert scale. Although statistically significant, this difference is not considered clinically significant (95655).

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General ...Orally, fo-ti may be unsafe.
Most Common Adverse Effects:
Orally: Abdominal pain, diarrhea, nausea, and vomiting with use of unprocessed fo-ti.
Serious Adverse Effects (Rare):
Orally: Hepatotoxicity with processed or unprocessed fo-ti.

Dermatologic ...Orally, one case of a fine maculopapular rash was reported in a patient taking the herbal product known as Shen-Min, which contains fo-ti. Symptoms resolved within three weeks after discontinuing the product (14482). It is unclear if the rash was due to fo-ti or other ingredients in the herbal product.

Gastrointestinal ...Orally, unprocessed fo-ti may cause diarrhea, abdominal pain, nausea, and vomiting (12,50733).

Hematologic ...Orally, one case of mild eosinophilia was reported in a patient taking the herbal product known as Shen-Min, which contains fo-ti. Symptoms resolved within three weeks after discontinuing the product (14482). It is unclear if this reaction was due to fo-ti or other ingredients in the herbal product. A case of agranulocytosis was reported in a 65-year-old female taking fo-ti 30 grams/day for 17 days. The patient recovered gradually following a 15-day hospitalization, which included treatment with intravenous steroids and granulocyte colony-stimulating factor (112231).

Hepatic ...Orally, cases of liver damage due to both processed and unprocessed fo-ti have been well documented in the medical literature. (7626,7627,14327,14339,14347,14482,16459,17192,50711,50726)(50727,50729,92892,92895,112231).
In a systematic review, around 450 cases of hepatitis associated with fo-ti were identified. These cases occurred in patients 5-78 years of age. Liver damage occurred at a wide range of doses, formulations, and durations of intake. The type of liver injury ranged from hepatocellular, to cholestatic, or mixed. Outcomes ranged from full recovery to cirrhosis, liver transplantation, and/or death. The evidence suggests that when the daily fo-ti dose is less than 12 grams, the median time to occurrence of liver damage is 60 days. When the daily fo-ti dose is more than 12 grams, the median time to liver damage is 30 days (92895). Presenting signs and symptoms may include jaundice, abdominal pain, nausea, fatigue, loss of appetite, dark urine, myalgias, and elevations in liver function tests (LFTs), ferritin, transferrin, prothrombin time, and INR (17192,92892). Other manifestations may include fever, skin rash, thrombocytopenia, pancytopenia, and arthralgias. Symptoms and increased LFTs usually seem to resolve within a month after discontinuing fo-ti (7626,7627,14339,14347,14482,16459). In one case series, liver enzymes began to normalize 48 hours after discontinuation of fo-ti and treatment with S-adenosylmethionine, compound glycyrrhizin injection, polyene phosphatidylcholine, and reduced glutathione. All patients were eventually discharged home in stable condition (92892). Rechallenge with fo-ti should not be attempted. A patient who had recovered from hepatitis associated with fo-ti use presented with myalgias and markedly elevated LFTs after a single dose of the herb (17192).
It is thought that this idiosyncratic reaction leading to liver damage is at least partially related to genetic polymorphisms. Cytochrome P450 1A2 (CYP1A2) is the predominant enzyme involved in biotransformation of emodin, a constituent of fo-ti thought to play a role in liver damage. In one genetic study, the frequency of CYP1A2*1C mutation in fo-ti induced drug-induced liver injury patients was 46.5%, which is significantly higher than the 27.9% frequency of liver injury reported in healthy patients without the mutation. Patients with a CYP1A2*1C mutation may have decreased activity of the CYP1A2 enzyme, which could inhibit the metabolism of fo-ti, causing an accumulation of toxic substances (92897).

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General ...Orally, guarana is typically well tolerated when used in moderation. Due to its caffeine content, use of large doses may be unsafe.
Most Common Adverse Effects:
Orally: Stomach burning and nausea.

Cardiovascular ...Orally, a case of premature ventricular contraction has been reported for a 51-year-old female who used guarana as part of a multi-ingredient herbal product (54372).
Guarana contains caffeine. Although acute administration of caffeine can increase blood pressure, regular consumption does not seem to increase either blood pressure or pulse, even in mildly hypertensive patients (1451,1452,2722). Also, epidemiological research suggests there is no association between caffeine consumption and increased incidence of hypertension. Habitual coffee consumption doesn't seem to be related to hypertension, but habitual consumption of sugared or diet cola is associated with development of hypertension (13739).
Combining ephedra with guarana can increase the risk of adverse effects. Cases of hypertension and chest pain have been reported for patients who took products containing guarana and ephedra (8644,54376). A case of cerebral infarction has also been reported for a patient consuming ephedra extract and guarana (48746). There is also a 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).

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

Endocrine ...Guarana contains caffeine. Some evidence shows caffeine is associated with fibrocystic breast disease, breast cancer, and endometriosis; however, this is controversial since findings are conflicting (8043). Restricting caffeine in people 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).
Although the effects of guarana alone are not clear, the combination of guarana along with ephedra has been reported to cause increased blood glucose levels and decreased blood levels of potassium (54376).

Gastrointestinal ...Orally, guarana can cause a sensation of burning in the stomach and vomiting (54414,91487). These effects may be due to caffeine in guarana. Orally, caffeine can cause gastric irritation, nausea, and vomiting (11832,11838,13735). In infants, caffeine may also cause feeding intolerance and gastrointestinal irritation (6023).

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

Musculoskeletal ...In a clinical trial of guarana extract, one person abandoned treatment due to symptoms of arthritis with edema. It is not clear if this adverse effect is due to guarana (91487).
Cases of rhabdomyolysis and myoglobinuria have been reported in individuals that have taken products containing guarana in combination with ephedra and other herbal products. These adverse effects are thought to be related to the caffeine content of guarana (19154,36466).
Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can increase urinary excretion of calcium (2669,10202,11317). Women 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, less than 300 mg per day, does not seem to significantly increase osteoporosis risk in most postmenopausal women with normal calcium intake (2669,6025,10202,11317).

Neurologic/CNS ...Orally, guarana can cause dizziness (91483). The caffeine in guarana can cause insomnia (especially in children), nervousness, restlessness, dizziness, tremors, delirium, and convulsions. Other symptoms include headache, anxiety, and agitation (10755,11832,11838,13735,108016).
Taking guarana with ephedra can cause insomnia, irritability, dizziness, and headache (3719). The combination of ephedra and caffeine in guarana might also increase the risk of adverse effects such as jitteriness, seizures, and temporary loss of consciousness (2729,21015).

Ocular/Otic ...Guarana contains caffeine. When taken orally, caffeine can cause ringing in the ears (11832,11838,13735).

Psychiatric ...In a clinical trial, depression was reported by one person taking guarana extract (91483).

Renal ...Guarana contains caffeine. When taken orally, caffeine can cause diuresis (11832,11838,13735).

Other ...Guarana contains caffeine. 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). Other researchers suggest 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). 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).

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General ...Orally, rose geranium oil is well tolerated when used in food amounts. Topically, rose geranium oil seems to be well tolerated, short-term.

Dermatologic ...Topically, rose geranium oil has been associated with reports of dermatitis in hypersensitive individuals and burning sensations when applied to the face (16653).

Gastrointestinal ...When applied with droppers in the nose, rose geranium oil has been reported to cause a bad taste (93881).

Neurologic/CNS ...Topically, rose geranium oil has been associated with reports of lightheadedness and eye irritation when applied to the face (16653).

Ocular/Otic ...Topically, rose geranium oil has been associated with reports of eye irritation when applied to the face (16653).

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