Common Names

  • Guarana gum
  • Guarana seed
  • Zoom cocoa
  • Brazilian cocoa

For Patients & Caregivers

How It Works

Guarana contains caffeine, and therefore has stimulant effects. Long-term effects of using guarana are not known.

Guarana is extracted from the seed and gum of a plant found in the Amazon Basin. It is commonly used in beverages because of its flavor and because it contains high levels of caffeine. Scientists are very familiar with how caffeine affects the body: it prolongs the action of the sympathetic nervous system (responsible for our “fight or flight” response) and therefore stimulates the brain, heart and muscles, and increases blood pressure.

Guarana showed anticancer, neuroprotective, and anti-anxiety properties in lab studies. A population study showed that guarana intake protected elderly subjects against metabolic disorders. A few small studies in cancer patients suggest guarana may help reduce chemotherapy-related fatigue, stabilize weight, and increase appetite. However, it did not reduce fatigue after radiation therapy, or in patients with head and neck cancers, and some symptoms worsened compared with a placebo. Further research is needed.

Purported Uses
  • As an appetite suppressant
    No scientific evidence supports this use.
  • As a stimulant
    Guarana contains caffeine, which has known stimulant effects.
  • To treat fatigue
    Results from studies of guarana to treat fatigue in cancer patients are mixed, and in one study of head and neck cancer patients, some symptoms worsened. Additional research is needed.
  • To improve sexual performance
    No scientific evidence supports this use.
Do Not Take If
  • You are taking anticoagulant or antiplatelet medications: Guarana has antiplatelet activity and can have additive effects.
Side Effects
  • Increased water lost from the body as urine
  • Insomnia

Case Reports

  • Seizures: In 4 healthy young adults following consumption of energy drinks that contained guarana along with other ingredients.
  • Vomiting, agitation, irregular heartbeat, high blood pressure, or nausea:  With abuse or misuse of guarana-containing supplements.

Back to top

For Healthcare Professionals

Scientific Name
Paullinia cupana
Clinical Summary

Guarana, a bushy plant prevalent in the Amazon Basin, has been used in traditional medicine to treat fevers, headaches, and dysentery. Actions of guarana are attributed primarily to caffeine present in its seeds (2) (3). It is promoted as an appetite suppressant, stimulant, as an aphrodisiac, and to alleviate fatigue. There are extensive data regarding caffeine and its activity.

In vitro studies indicate that guarana has chemopreventive (11) (12), neuroprotective, (13) and anxiolytic (14) properties. Epidemiologic data suggest its protective effects against metabolic disorders in elderly populations (15). Improvements in cognitive performance and mental fatigue were also observed following supplementation with guarana in healthy adults (16).

A few small studies in cancer patients suggest guarana may help reduce chemotherapy-related fatigue, stabilize weight, and increase appetite (22) (25) (26). However, it did not reduce fatigue post-radiation (17) or in patients with head and neck cancers, and some symptoms worsened compared with a placebo (27). Further research is needed.

Purported Uses
  • Appetite suppression
  • Central nervous system stimulation
  • Fatigue
  • Sexual performance
Mechanism of Action

Many of guarana’s effects are thought to be due to its high caffeine content. Caffeine’s actions include CNS stimulation, cardiac stimulation, diuresis, increase in blood pressure, inhibition of platelet aggregation, skeletal muscle stimulation and causing hyperglycemia (2) (3). Guarana demonstrated antioxidant effects by inhibiting lipid peroxidation (19). Chronic exposure to Guarana seed extract produced an anxiolytic effect involving the dopaminergic and serotonergic neurotransmission systems (14).

Adverse Reactions

Case Reports

  • Vomiting, agitation, tachycardia, hypertension, or nausea: Pediatric cases with abuse or misuse of guarana-containing supplements (28).
  • Tachycardia: In 2 women consuming guarana-containing supplement/energy drinks (29).
  • Premature ventricular contractions: In a 25-year-old woman with pre-existing mitral valve prolapse following consumption of guarana (7).
  • Seizures: In 4 healthy young adults following consumption of an energy drink that contained guarana along with other ingredients (18).
Herb-Drug Interactions

Anticoagulant or Antiplatelet drugs: Guarana demonstrated antiplatelet activity and can therefore have additive effects (20) (21).
Amiodarone: A study done in rats showed that Guarana extract decreases the bioavailability of amiodarone (24).

Herb Lab Interactions

May cause arrhythmia
Blood pressure may be elevated

Dosage (OneMSK Only)
  1. McGuffin M. A Botanical Safety Handbook. Boca Raton (FL): CRC Press; 1997.

  2. Gruenwald J, et al. PDR for Herbal medicines, 2nd ed. Montvale (NJ): Medical Economics Company; 1998.

  3. Schulz V, et al. Rational Phytotherapy: A Physicians Guide to the Use of Herbs and Related Remedies, 3rd ed. Berlin (Germany): Springer; 1998.

  4. Fetrow CW, et al. Professional’s Handbook of Complementary and Alternative Medicines. Philadelphia: Springhouse; 1999.

  5. McEvoy GK, et al. AHFS Drug Information. Bethesda (MD): ASHP; 1998.

  6. Brinker F. Herb Contraindications and Drug Interactions, 2nd ed. Sandy (OR): Eclectic; 1998.

  7. Cannon ME, Cooke CT, McCarthy JS. Caffeine-induced cardiac arrhythmia: an unrecognized danger of healthfood products. Med J Aust 2001;174:520-1.

  8. Robbers JE. Tyler’s Herbs of Choice: The Therapeutic Use of Phytomedicinals. New York: Haworth Herbal Press; 1999.

  9. Wallach J. Interpretation of Diagnostic Tests: A synopsis of laboratory medicine. Boston: Little, Brown, & Company; 1992.

  10. Boozer CN, et al. An herbal supplement containing Ma Huang-Guarana for weight loss: a randomized, double-blind trial. Int J Obes Related Metab Disord 2001;25:316-24.

  11. Fukumasu H, Cristina da Silva T, Avanzo JL, et al. Chempreventive effects of Puallinia cupana Mart var. sorbilis, the guarana, on mouse hepatocarcinogenesis. Cancer Lett 2006 20;233(1):158-64.

  12. de Oliveira DM, Barreto G, Galeano P, et al. Paullinia cupana Mart. var. Sorbilis protects human dopaminergic neuroblastoma SH-SY5Y cell line against rotenone-induced cytotoxicity. Hum Exp Toxicol. 2010 Nov 16. [Epub ahead of print]

  13. Roncon CM, Biesdorf de Almeida C, Klein T, Palazzo de Mello JC, Audi EA. Anxiolytic effects of a semipurified constituent of guaraná seeds on rats in the elevated T-maze test. Planta Med. 2011 Feb;77(3):236-41.

  14. Costa Krewer C, Ribeiro EE, Ribeiro EA, et al. Habitual Intake of Guaraná and Metabolic Morbidities: An Epidemiological Study of an Elderly Amazonian Population. Phytother Res. 2011 Feb 22.

  15. Kennedy DO, Haskell CF, Robertson B, et al. Improved cognitive performance and mental fatigue following a multi-vitamin and mineral supplement with added guaraná (Paullinia cupana). Appetite. 2008 Mar-May;50(2-3):506-13. Epub 2007 Oct 30.

  16. 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 Apr;15(4):431-3.

  17. Iyadurai SJ, Chung SS. New-onset seizures in adults: possible association with consumption of popular energy drinks. Epilepsy Behav. 2007 May;10(3):504-8.

  18. 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 Mar;60(2):111-6.

  19. Bydlowski SP, D’Amico EA, Chamone DA. An aqueous extract of guaraná (Paullinia cupana) decreases platelet thromboxane synthesis. Braz J Med Biol Res. 1991;24(4):421-4.

  20. de Oliveira Campos MP, Riechelmann R, Martins LC, et al. Guarana (Paullinia cupana) improves fatigue in breast cancer patients undergoing systemic chemotherapy. J Altern Complement Med. 2011 Jun;17(6):505-12.

  21. Yamaguti-Sasaki E, Ito LA, Canteli VC, et al. Antioxidant capacity and in vitro prevention of dental plaque formation by extracts and condensed tannins of Paullinia cupana. Molecules. 2007 Aug 20;12(8):1950-63.

  22. Rodrigues M, Alves G, Lourenço N, Falcão A. Herb-Drug Interaction of Paullinia cupana (Guarana) Seed Extract on the Pharmacokinetics of Amiodarone in Rats. Evid Based Complement Alternat Med. 2012;2012:428560.

  23. 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.

  24. Biggs JM, Morgan JA, Lardieri AB, et al. Abuse and Misuse of Selected Dietary Supplements Among Adolescents: a Look at Poison Center Data. J Pediatr Pharmacol Ther. Nov-Dec 2017;22(6):385-393.

Back to top
Back to top
Email your questions and comments to

Last Updated