guarana (generic name)

an herbal product - treats Cognitive enhancement, Mood enhancement, and Weight loss
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Adults (over 18 years old)

There is no proven effective dose for guarana. Teas, capsules and energy drinks are all commercially available. For cognitive enhancement, a single dose of 150 milligrams guarana dry extract, standardized to 11-13% alkaloid concentration has been used. One gram of guarana up to four times a day has been taken to relieve diarrhea or dysentery. As a diuretic, 486 milligrams of guarana daily has been used. One to two tablets or capsules (200-800 milligrams guarana extract) before breakfast or lunch, not to exceed 3 grams daily, has reportedly been used for energy enhancement.

Children (under 18 years old)

There is no proven safe or effective dose for guarana in children.


DISCLAIMER: Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.


Avoid in individuals with a known allergy or hypersensitivity to guarana (Paullinia cupana), caffeine, tannins or related species of the Sapindaceae family. Caffeine, a prominent constituent of guarana, may have an inhibitory effect on type-I allergic reactions.

Side Effects and Warnings

Guarana is generally well-tolerated. A majority of information related to adverse effects of guarana is based in theory upon the adverse effect profile of caffeine. The effects of caffeine are likely more pronounced at age extremes, in the elderly and in children. The chronic use of caffeine, especially in large amounts, may produce tolerance, habituation, and psychological dependence. Abrupt discontinuation of caffeine can result in physical withdrawal symptoms including headache, irritation, nervousness, anxiety, and dizziness.

Caffeinism and caffeine withdrawal may be indistinguishable from anxiety neurosis (physical symptoms of anxiety), and caffeine intoxication may cause psychosis (mental disorder). In various cases, anxiety disorders and somatic dysfunctions could be linked to caffeine intake. However, in a study of schizophrenic inpatients, no correlation was found between levels of anxiety, depression or other behavior, and caffeine consumption. Caffeine has been reported to increase mental alertness, physical energy, enhanced mood and physical performance and endurance. Avoid use in patients with psychological or psychiatric disorders as guarana may exacerbate symptoms.

Seizures, muscle spasms, and convulsions have been reported from caffeine overdose. Lifetime caffeinated coffee intake equivalent to two cups a day without daily milk consumption (or calcium intake below RDA) in women as has been associated with significantly decreased bone density, and bone loss in older women. Use cautiously in individuals at risk for osteoporosis, as caffeine may increase urinary excretion of calcium. Cases of rhabdomyolysis and myoglobinuria have been related to toxic effects of caffeine. Caffeine-induced insomnia has also been extensively studied.

Consuming large amounts of caffeine per day may increase the risk of breast disease, tachycardia (increased heart rate) or high blood pressure, although there is controversy in this area. Nevertheless, use cautiously in patients with pre-existing mitral valve prolapse, as intractable ventricular fibrillation has been reported in a case associated with high dosage caffeine consumption.

Several studies have found no connection between coronary heart disease and habitual coffee drinking. The Framingham Study did not find an association between coffee-drinking and atherosclerotic (hardening of the blood vessels) cardiovascular disease in the general population. In another large study, there was no significant association between coffee consumption and angina (chest pain).

An increase in blood glucose may occur after low caffeine ingestion. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugar. Serum glucose levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.

Theoretically, the caffeine in guarana may increase the bioavailability and absorption of tannins, and thus decrease the absorption of nutrients. Weight loss, delayed gastric emptying time, and perceived gastric fullness have been attributed to a combination guarana product also containing yerba maté and damiana. "Burning in the stomach," worsening of ulcer symptoms, and urticaria ("hives") have also been reported.

Guarana may increase the risk of bleeding. Caution is advised in patients with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.

Adverse effects reported secondary to ingestion of a combination of ma huang and guarana included insomnia, anxiety, headache, irritability, poor concentration, blurred vision, and dizziness. Other symptoms include hyper-excitation, tremor, nervousness, cerebral infarction (stroke), changes in voice quality, and palpitations (with and without chest pain). Avoid use in combination with other stimulatory agents, especially ephedra, due to reports of death and permanent disability associated with this combination.

Ingestion of caffeine has increased intraocular pressure in two glaucoma patients. Use cautiously in individuals with glaucoma.

Guarana may produce a diuretic effect. A reduction of caffeine may reduce the episodes of leakage per day in patients with symptoms of urinary frequency, and/or urge incontinence. Caffeine may cause dysuria (difficulty or pain urinating). High caffeine intake has been shown to worsen the condition of detrussor instability (unstable bladder) in older women. Use cautiously in patients with impaired kidney function.

Use cautiously in individuals with an iron deficiency due to possible association with the development of anemia.

Avoid in patients with liver impairment, as the clearance of caffeine may be impaired.

Pregnancy & Breastfeeding

Studies on caffeine, the active constituent in guarana, indicate that consumption of caffeine may increase certain risks in pregnant women, although there is controversy in this area. For instance, high levels of caffeine consumption may result in delayed conception among women who are nonsmokers. Several studies found an association between caffeine and low birth weight. Heavy caffeine intake throughout pregnancy may increase the risk for SIDS (sudden infant death syndrome). Three cases of birth defects have been associated with excessive caffeine intake. Studies in pregnant women drinking moderate amounts of caffeine have shown inconsistent results, with more recent studies reporting no adverse effects on the fetus.

Caffeine consumption may increase the risk of an early spontaneous abortion among non-smoking women. Heavy caffeine consumers reporting nausea had a doubled risk for spontaneous abortion. Light caffeine use has been associated with risk for spontaneous abortion among women who aborted in their last pregnancy.

Caffeine is readily transferred into breast milk. Infant caffeine ingestion can lead to infant sleeping disturbances. The effect of other substances contained in guarana is unknown. Breastfeeding may inhibit the caffeine metabolism in infants due to human milk components. Babies from mothers who consumed large amounts of caffeine daily have experienced tremors, and some experienced cardiac rhythm disturbances.

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