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Scientific Name(s): Paullinia cupana Kunth var. sorbilis (L.)
Common Name(s): Brazilian cocoa, Guarana, Guarana gum, Guarana paste, Zoom
Drug class: Herbal products

Medically reviewed by Last updated on Dec 30, 2020.

Clinical Overview


Guarana has traditionally been used as a natural energizer and cognitive stimulant, as flavoring in beverages, and as a component in natural weight loss products; however, clinical data do not support use as a natural energizer or weight loss aid. Limited clinical trials have been conducted with guarana alone, with some evidence for use in chemotherapy-related fatigue.


Doses ranging from 75 mg to 1,000 mg daily were administered in limited clinical trials.


Guarana is contraindicated in pregnancy and lactation.


Use is contraindicated. Low birthweight, birth defects, and premature birth have been documented with guarana use.


Caffeine, a principal constituent of guarana, is unsafe as a food additive when combined with alcohol (ie, alcoholic beverages with added caffeine).

Adverse Reactions

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


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

Scientific Family

  • Sapindaceae (Soapberry)


P. cupana or Paullinia sorbilis are fast-growing, woody, perennial shrubs native to Brazil and other regions of the Amazon. The trees have large leaves and clusters of flowers that bear orange-yellow fruits containing up to 3 seeds each, similar in size to a coffee bean. Guarana is the dried paste made from the crushed seeds of P. cupana.1, 2


Historically, guarana 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. Guarana has been traditionally used in South America and by Amazonian Indians to increase awareness and energy. In certain regions, the extract is believed to be an aphrodisiac and protectant against malaria and dysentery. In 19th century France, guarana became popular as an ingredient in beverages, due to its stimulant properties. In 1880, guarana was introduced as an official drug in the United States Pharmacopeia, where it remained listed until 1910. Natural diet aids containing daily doses of guarana (occasionally combined with glucomannan) have been advertised in the lay press. Guarana has also been used during periods of fasting to suppress appetite. Today, the most common forms of guarana include syrups, extracts, and distillates used for flavoring and as sources of caffeine by the soft drink industry. Indian tribes in Brazil use guarana for its stimulant properties in beverages such as tea or coffee; it is sometimes mixed with alcohol to make a more intoxicating beverage.3, 4, 5, 6, 7


In 1840, caffeine was identified as guarana's principal constituent, with levels ranging from 3% to greater than 5% by dry weight.7 By comparison, coffee beans contain approximately 1% to 2% of caffeine and the content in dried tea leaves varies from 1% to 4%.8 The related alkaloids theophylline and theobromine have also been identified in guarana. Guarana is high in tannins (primarily catechutannic acid and catechol), which are present in concentrations of 5% to 6% dry weight; these impart an astringent taste.8

Trace amounts of a saponin known as timbonine, related to compounds reported in timbo fish poisons used by Amazonian Indians, have been reported.4

Uses and Pharmacology

Limited clinical trials have been conducted using guarana alone.7, 9

Cognitive stimulant/CNS effects

Animal data

One study examined behavioral effects in rats and mice after acute and chronic guarana administration. Animals treated with guarana doses of 2,000 mg/kg showed no difference when compared with control groups in motor activity, tremor, or salivation parameters.10 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.11

Clinical data

In a small study, 3 groups of healthy volunteers 20 to 35 years of age were given placebo, caffeine 25 mg, or 1,000 mg of guarana containing 2.1% caffeine (21 mg) daily. After 4 days, no reproducible improvement in cognition was noted in any group according to neuropsychological testing, assessment of sleep quality, and a State-Trait Anxiety Inventory.12 In another small study, the effects of long-term guarana administration on the cognition of healthy, elderly volunteers was assessed. Guarana did not result in statistically significant memory improvement.13

In an Italian randomized, single-blind, crossover trial of 27 healthy volunteers, guarana 350 mg (2.5% caffeine) 3 times daily for 5 days did not produce any effects on psychological well-being, anxiety, or mood compared with placebo. However, a subpopulation of female participants reported an increase in self-acceptance scores.14

A group of researchers in Brazil evaluated the effect of guarana on chemotherapy-related fatigue, and reported favorable outcomes for guarana 37.5 mg to 75 mg orally twice daily.15, 16, 17, 18 In 2018, the American Society of Clinical Oncology (ASCO) endorsed the Society for Integrative Oncology (SIO) evidence-based guideline for the use of integrative therapies after breast cancer treatment, stating that acetyl-L-carnitine should not be recommended for improving fatigue during treatment (Grade D).30

Other uses

Some researchers suggest that the revitalizing effects of guarana result partly from its antioxidant action.10

Guarana's potential appetite suppressant and energy-inducing effects are likely related to its caffeine content. Numerous investigational studies have shown the sympathetic stimulant ephedrine, when combined with caffeine, demonstrates a synergistic effect on increasing metabolic rates, with subsequent increased energy expenditure (thermogenesis), as well as lipolytic actions.19 These effects resulted in statistically significant weight loss when guarana was combined with diet in short-term animal and clinical trials. However, a review reports a lack of unequivocal benefits of guarana over water or sports drinks.3

A study in rats with diet-induced hypercholesterolemia demonstrated reductions from baseline levels in total cholesterol and low-density lipoprotein cholesterol with guarana doses of 12.5, 25, or 50 mg/day for 4 weeks.20

The effects of a guarana extract (12.24 mg/g of caffeine) on 7 chemotherapeutic drugs used in the treatment of breast cancer were tested in vitro in a breast cancer cell line. Cell proliferation decreased about 20% to 25% with the extract alone, but guarana extract plus cyclophosphamide resulted in an 80% decrease in cancer cell population compared to the control group after 72 hours. Guarana added to the other 6 agents resulted in decreases in cell proliferation of 40% to 50%.21


Doses ranging from 75 mg to 1,000 mg daily have been used in limited clinical trials evaluating stimulant effects.9

A group of researchers in Brazil evaluated the effect of guarana on chemotherapy-related fatigue and reported favorable outcomes with doses of 37.5 mg to 75 mg orally twice daily.15, 16, 17, 18

Pregnancy / Lactation

Use is contraindicated. Low birthweight, birth defects, and premature birth have been documented with guarana use.22


The Food and Drug Administration (FDA) has ruled that caffeine is unsafe as a food additive when combined with alcohol (ie, alcoholic beverages with added caffeine).1, 23 In vitro, guarana extract inhibited aggregation of platelets, possibly due to inhibition of platelet thromboxane synthesis.24

Based on the caffeine content of guarana, interactions with clozapine, lithium, anxiolytic agents, pseudoephedrine, and antihypertensive agents are theoretically possible.25

Adverse Reactions

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


Case reports of dysrhythmias and seizures related to overconsumption of energy drinks exist in the literature;3, 26, 27 however, most cases of toxicity in adults appear to be mild and clinically benign. Accidental overdose in children may be more serious.27, 28 Pure caffeine/guaranine is potentially fatal at a dose of 10 g.8

Because of its high tannin content, excessive use of guarana may lead to an increased risk of cancer of the oropharynx.29

Index Terms

  • Paullinia sorbilis


1. Serious concerns over alcoholic beverages with added caffeine. U.S. Food and Drug Administration website. Published November 17, 2010.Accessed April 28, 2017.
2. Duke J, Bogenschutz-Godwin M, duCellier J, Duke P. Handbook of Medicinal Herbs. 2nd ed. Boca Raton, FL: CRC Press; 2002.
3. Higgins JP, Tuttle TD, Higgins CL. Energy beverages: content and safety. Mayo Clin Proc. 2010;85(11):1033-1041.21037046
4. Henman AR. Guaraná (Paullinia cupana var. sorbilis): ecological and social perspectives on an economic plant of the central Amazon basin. J Ethnopharmacol. 1982;6(3):311-338.
5. Lewis W, Elvin-Lewis MP. Medical Botany: Plants Affecting Man's Health. New York, NY: Wiley; 1977.
6. Steinmetz E. Guarana. J Crude Drug Res. 1965:749-751
7. Schimpl FC, da Silva JF, Gonçalves JF, Mazzafera P. Guarana: revisiting a highly caffeinated plant from the Amazon. J Ethnopharmacol. 2013;150(1):14-31.23981847
8. Burke LM, Stear SJ, Lobb A, Ellison M, Castell LM. A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance--Part 19. Br J Sports Med. 2011;45(5):456-458.21393262
9. Haskell CF, Dodd FL, Wightman EL, Kennedy DO. Behavioural effects of compounds co-consumed in dietary forms of caffeinated plants. Nutr Res Rev. 2013;26(1):49-70.23561485
10. Mattei R, Dias RF, Espínola EB, Carlini EA, Barros SB. Guarana (Paullinia cupana): toxic behavioral effects in laboratory animals and antioxidants activity in vitro. J Ethnopharmacol. 1998;60(2):111-116.9582000
11. Espinola EB, Dias RF, Mattei R, Carlini EA. Pharmacological activity of Guarana (Paullinia cupana Mart.) in laboratory animals. J Ethnopharmacol. 1997;55(3):223-229.9080343
12. Galduróz JC, Carlini Ede A. Acute effects of the Paulinia cupana, "Guaraná" on the cognition of normal volunteers. Sao Paulo Med J. 1994;112(3):607-611.7638522
13. Galduróz JC, Carlini EA. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Sao Paulo Med J. 1996;114(1):1073-1078.8984582
14. Silvestrini GI, Marino F, Cosentino M. Effects of a commercial product containing guaraná on psychological well-being, anxiety and mood: a single-blind, placebo-controlled study in healthy subjects. J Negat Results Biomed. 2013;12:9.23706111
15. de Oliveira Campos MP, Riechelmann R, Martins LC, Hassan BJ, Casa FB, Del Giglio A. Guarana (Paullinia cupana) improves fatigue in breast cancer patients undergoing systemic chemotherapy. J Altern Complement Med. 2011;17(6):505-512.21612429
16. del Giglio AB, Cubero Dde I, Lerner TG, et al. Purified dry extract of Paullinia cupana (guaraná) (PC-18) for chemotherapy-related fatigue in patients with solid tumors: an early discontinuation study. J Diet Suppl. 2013;10(4):325-334.24237188
17. da Costa Miranda V, Trufelli DC, Santos J, et al. Effectiveness of guaraná (Paullinia cupana) for postradiation fatigue and depression: results of a pilot double-blind randomized study. J Altern Complement Med. 2009;15(4):431-433.19388866
18. Palma CG, Lera AT, Lerner T, et al. Guarana (Paullinia cupana) improves anorexia in patients with advanced cancer. J Diet Suppl. 2016;13(2):221-231.25695932
19. Breum L, Pederson JK, Ahlstrøm F, Frimodt-Møller 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(2):99-103.8148931
20. Ruchel JB, Rezer JF, Thorstenberg ML, et al. Hypercholesterolemia and ecto-enzymes or purinergic system: effects of Paullinia cupana. Phytother Res. 2016;30(1):49-57.26514663
21. Hertz E, Cadoná FC, Machado AK, et al. Effect of Paullinia cupana on MCF-7 breast cancer cell response to chemotherapeutic drugs. Mol Clin Oncol. 2015;3(1):37-43.25469267
22. Ernst E. Herbal medicinal products during pregnancy: are they safe? BJOG. 2002;109(3):227-235.11950176
23. Marczinski CA, Fillmore MT. Energy drinks mixed with alcohol: what are the risks? Nutr Rev. 2014;72(suppl 1):98-107.25293549
24. Bydlowski S, D'Amico EA, Chamone DA. An aqueous extract of guaraná (Paullinia cupana) decreases platelet thromboxane synthesis. Braz J Med Biol Res. 1991;24(4):421-424.1823256
25. Woods DJ. Guarana: Paullinia cupana, P. sorbilis; also known as Brazilian cocoa and 'zoom'. J Prim Health Care. 2012;4(2):163-164.22675703
26. Iyadurai SJ, Chung SS. New-onset seizures in adults: possible association with consumption of popular energy drinks. Epilepsy Behav. 2007;10(3):504-508.17349826
27. Seifert SM, Seifert SA, Schaechter JL, et al. An analysis of energy-drink toxicity in the National Poison Data System. Clin Toxicol (Phila). 2013;51(7):566-574.23879181
28. Lüde S, Vecchio S, Sinno-Tellier S, et al. Adverse effects of plant food supplements and plants consumed as food: results from the Poisons Centres-based PlantLIBRA study. Phytother Res. 2016;30(6):988-996.26948409
29. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications; 1998.
30. Lyman GH, Greenlee H, Bohike K, et al. Integrative therapies during and after breast cancer treatment: ASCO endorsement of the SIO clinical practice guideline. J Clin Oncol. 2018;36(25):2647-2655.29889605


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This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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