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Medically reviewed on Feb 16, 2018

Scientific Name(s): Paullinia cupana Kunth var. sorbilis (L.) Family: Sapindaceae

Common Name(s): Guarana , guarana paste or guarana gum , Brazilian cocoa , zoom


Guarana has been used as a natural energizer, cognitive stimulant, flavoring for beverages, and as a component in natural weight loss products; however, it cannot be recommended as a natural energizer or weight loss aid.


Guarana paste is used as a stimulant at a dose of 1 g, usually dissolved in water or juice. The caffeine content is between 3.6% and 5.8%.


Contraindicated in pregnancy and lactation.


Documented low birthweight, birth defects, and premature birth. Avoid use.


None well documented.

Adverse Reactions

Excessive nervousness, insomnia, and other health risks in patients sensitive to caffeine.


Research reveals little or no information regarding severe toxicity with the use of this product. Given its high tannin content, excessive use may lead to an increased risk of cancer of the oropharynx.


Guarana is the dried paste made from the crushed seeds of P. cupana or P. sorbilis , fast-growing, woody perennial shrubs native to Brazil and other regions of the Amazon. 1 P. cupana and P. sorbilis bear orange-yellow fruits that contain up to 3 seeds each. Historically, the seeds were collected and dry-roasted over fire. The kernels were then ground to a paste with cassava and molded into cylindrical sticks, which were then sun dried. Today, the most common forms of guarana include syrups, extracts, and distillates used as flavorings and a source of caffeine by the soft drink industry. Guarana also is used as an ingredient in herbal weight loss preparations.


Guarana has played an important role in South American culture and in Amazonian Indian society. It is often taken during periods of fasting to suppress the appetite. In certain regions, the extract is believed to be an aphrodisiac and as protection from malaria and dysentery. 2 , 3 In the 19th century, guarana became popular as a stimulating drink in France, 1 and in 1880 it was introduced as an official drug in the United States Pharmacopeia , where it remained listed until 1910. 4 Natural diet aids, which rely on daily doses of guarana, have been advertised in the lay press. Guarana is occasionally combined with glucomannan in natural weight loss tablets.

The stems, leaves, and roots of guarana are used as a fish-killing drug in Central and South America.


In 1840, caffeine was identified as guarana's principal constituent, with a level ranging from 3% to greater than 5% by dry weight. 2

By comparison, coffee beans contain approximately 1% to 2% caffeine and the content in dried tea leaves varies from 1% to 4%. 5 The related alkaloids, theophylline and theobromine, have also been identified in guarana. Guarana is high in tannins (primarily catechutannic acid and catechol), present in concentrations of 5% to 6% dry weight; these impart an astringent taste. Guarana contains no cocaine.

Trace amounts of a saponin known as timbonine, related to compounds reported in timbo fish poisons used by Amazonian Indians, have been reported. 2

Uses and Pharmacology

Guarana is used by Brazilian Indians in a stimulating beverage consumed like tea or coffee; it is sometimes mixed with alcohol to prepare a more intoxicating beverage. 2

Cognitive stimulant effects
Animal data

In one study, behavioral effects in rats and mice subsequent to acute and chronic guarana administration were observed. 6 In this investigation, groups of animals treated with guarana in doses of 2,000 mg/kg showed no difference when compared with control groups in the parameters of motor activity, tremor, or salivation. Another study showed an increase in physical capacity when mice were subjected to a stressful situation, such as forced swimming, after 3 to 6 months of guarana treatment. 7

Clinical data

There are few human clinical trials evaluating the safety and efficacy of guarana. In a small study, 3 groups of healthy volunteers ranging from 20 to 35 years of age were given either placebo, caffeine 25 mg, or 1,000 mg of guarana containing 2.1% caffeine daily. After 4 days, no reproducible improvement in cognition was noted in any group using neuropsychological testing, assessment of sleep quality, and a State-Trait Anxiety Inventory. 8 In another study, the effects of long-term guarana administration on the cognition of healthy, elderly volunteers were studied. Guarana did not result in statistically significant memory improvement. 9

Other uses

Guarana extract has been shown to inhibit aggregation of platelets following either parenteral or oral administration, possibly due to inhibition of platelet thromboxane synthesis. 10

Some researchers claim that part of the revitalizing effects of guarana may result from its antioxidant action. 6

The appetite suppressant and energy-inducing effects are related to the caffeine content. Numerous investigational studies have shown the sympathetic stimulant ephedrine, when combined with caffeine, to have a synergistic effect on increasing metabolic rates with subsequent increased energy expenditure (thermogenesis), and to have lipolytic actions. 11 These effects have resulted in statistically significant weight loss in animal and human trials when combined with diet.


Guarana paste is used as a stimulant at a dose of 1 g, usually dissolved in water or juice. The caffeine content is between 3.6% and 5.8%. 12


There has been documented low birthweight, birth defects, and premature birth with guarana use. 13 Use is contraindicated.


None well documented.

Adverse Reactions

Those sensitive to caffeine, including patients taking herbal weight loss preparations, should use guarana with caution. Guarana use has led to excessive nervousness and insomnia.


There are no published reports describing severe toxicity from guarana; however, given its high tannin content, excessive use may lead to an increased risk of cancer of the oropharynx. 14


1. Angelucci E, et al. Chemical evaluation of guarana seed ( Paullinia cupana var. sorbilis Ducke). Bol Inst Tec Aliment . 1978;56:183-192.
2. Henman A. Guarana ( Paullinia cupana var. sorbilis ): ecological and social perspectives on an economic plant of the central Amazon basin. J Ethnopharmacol . 1982;6:311-338.
3. Lewis W, Elvin-Lewis MP. Medical Botany: Plants Affecting Man's Health . New York: Wiley; 1977.
4. Steinmetz E. Guarana. J Crude Drug Res . 1965:749-751.
5. Der Marderosian A, Liberti LE. Natural Product Medicine: A Scientific Guide to Foods, Drugs, Cosmetics . Philadelphia, PA: G.F. Stickley Co.; 1988.
6. Mattei R, Dias RF, Espinola EB, Carlini EA, Barros SB. Guarana ( Paullinia cupana ): toxic behavioral effects in laboratory animals and antioxidants activity in vitro. J Ethnopharmacol . 1998;60:111-116.
7. Espinola E, Dias RF, Mattei R, Carlini EA. Pharmacological activity of Guarana ( Paullinia cupana Mart.) in laboratory animals. J Ethnopharmacol . 1997;55:223-229.
8. Galduroz J, Carlini Ede A. Acute effects of the Paulinia cupana , “Guarana” on the cognition of normal volunteers. Sao Paulo Med J . 1994;112:607-611.
9. Galduroz J, Carlini EA. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Sao Paulo Med J . 1996;114:1073-1078.
10. Bydlowski S, D'Amico EA, Chamone DA. An aqueous extract of guarana ( Paullinia cupana ) decreases platelet thromboxane synthesis. Braz J Med Biol Res . 1991;24:421-424.
11. Breum L, Pederson JK, Ahlstrom F, Frimodt-Moller J. Comparison of an ephedrine/caffeine combination and dexfenfluramine in the treatment of obesity. A double-blind multi-centre trial in general practice. Int J Obes Relat Metab Disord . 1994;18:99-103.
12. Claus E. Pharmacognosy . 3rd ed. Philadelphia, PA: Lea & Febiger; 1956.
13. Ernst E. Herbal medicinal products during pregnancy: are they safe? BJOG . 2002;109:227-235.
14. Brinker F. Herb Contraindications and Drug Interactions . 2nd ed. Sandy, OR: Eclectic Medical Publications; 1998.

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