# Guarana (Paullinia cupana) *Guarana bread, Brazilian cocoa, uabano, uaranzeiro; *Paullinia sorbilis* of Martius; *Paullinia cupana* Kunth; in pharmacy *Paulliniae semen** **Known today as.** *Paullinia cupana*, a climbing shrubby vine of the family Sapindaceae native to the Amazon basin, whose pear-shaped fruit holds a seed which Grieve likens to a small horse chestnut half enclosed in a flesh-coloured aril. Guarana proper is the paste of the roasted, shelled, pounded seeds, kneaded with water into a dough, rolled into cylinders, and dried over a slow fire; King’s Dispensatory describes the sticks as hard, dark reddish-brown, with a slight odour “resembling that of chocolate” and an astringent, bitter taste. The genus takes its name from C. F. Paullini, a German medical botanist. Kind: Plant > **Caution.** Not for people with stomach or duodenal ulcers, high blood pressure, irregular heartbeat or other heart disorders, or an overactive thyroid, nor under eighteen; not before bedtime, since it may disturb sleep. People taking MAO inhibitors should use it with caution, and its caffeine increases the side effects of sympathomimetic drugs. LiverTox warns that high doses can cause tremor, agitation, confusion, high blood pressure, and dehydration, and that combining several products containing guarana and other caffeine sources can lead to caffeine toxicity; it has not been convincingly linked to liver injury. ## What was it used for? A stimulating drink and a remedy for headache. Grieve records that Brazilian miners grated the sticks into sugar and water and drank it like tea, believing it “a preventive of many diseases, as well as a most refreshing beverage,” carrying a stick in their pockets with the palate bone or a scale of a large fish to grate it. King’s Dispensatory, like coffee and tea, calls it “a gentle excitant,” useful when the brain is irritated or depressed by mental over-exertion, and chiefly in nervous headache, the headache of menstruation, “and that following a course of dissipation.” ## What does modern science say? The European Medicines Agency’s herbal committee accepts the seed as a traditional herbal medicine, “exclusively based upon long-standing use,” for symptoms of fatigue and a sensation of weakness (monograph of 2013). Its assessment report finds 1.1 to 5.8 per cent of caffeine with smaller amounts of theobromine and theophylline, 9.5 to 16 per cent of tannins, mainly proanthocyanidins, and about 30 per cent of starch. Trials of its use against the fatigue of cancer disagree: a 2021 meta-analysis of three breast-cancer studies found it no better than placebo, on very low quality evidence, while a 2024 meta-analysis of five studies in 229 patients found a significant benefit despite high heterogeneity. A 2023 meta-analysis of eight placebo-controlled studies found that a single dose quickened response times a little without improving accuracy, and that it was unknown whether caffeine or something else was responsible. LiverTox, revised in 2023, judges that most of its effects and side effects can be explained by its caffeine. ## Pharmacognosy and toxicology - **caffeine**: 1.1 to 5.8 per cent of the seed - **theobromine**: smaller amounts, with theophylline - **theophylline**: - **proanthocyanidins**: most of the tannins, 9.5 to 16 per cent **Mechanism.** LiverTox judges that most of its effects and side effects can be explained by its caffeine. **Standing.** European Union herbal monograph (2013): traditional use, “exclusively based upon long-standing use,” for fatigue and a sensation of weakness. Meta-analyses of its use in cancer fatigue disagree (2021, 2024). ## What lore surrounds it? Grieve says the seeds were mixed with cassava and water and left to ferment until almost putrid, to make a favourite drink of the Orinoco Indians, and that guarana “is only made by the Guaranis.” LiverTox notes that the seeds hold 2 to 8 per cent of caffeine, far more than coffee beans. ## What did the older authorities say? **King’s American Dispensatory (1898).** Guarana “was introduced into France in the year 1817, by a French officer,” and described that year by Gassicourt in the *Journal de Pharmacie* before its plant was known; it was named after the Guaranis, who prepared it, and in 1826 Martius identified the plant and named it *Paullinia sorbilis*, from its use for a drink. Once loudly heralded for diarrhoea, it was by 1898 used chiefly for certain headaches, and was contraindicated wherever it was not desirable to excite the heart or raise the arterial tension. ## Sources - Grieve, M. *A Modern Herbal*, “Guarana.” As published on botanical.com. - Felter, H. W., & Lloyd, J. U. (1898). *King’s American Dispensatory*, vol. 2, “Guarana.” Internet Archive, kingsamericandis02kinguoft. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Paulliniae semen (Guarana)*. EMA/HMPC/897344/2011, 15 January 2013. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Paulliniae semen*. EMA/HMPC/897384/2011, 15 January 2013. - de Araujo DP, et al. (2021). The use of guarana (Paullinia cupana) as a dietary supplement for fatigue in cancer patients: a systematic review with a meta-analysis. *Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer*. PMID 34146166. - Maselli-Schoueri JH, et al. (2024). Natural supplementation to effectively treat cancer-induced fatigue: evidence of a meta-analysis on the use of guaraná. *Revista da Associacao Medica Brasileira (1992)*. PMID 39536249. - Hack B, et al. (2023). Effect of Guarana (Paullinia cupana) on Cognitive Performance: A Systematic Review and Meta-Analysis. *Nutrients*. PMID 36678305. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Guarana.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2023. NCBI Bookshelf. - European Medicines Agency, Committee on Herbal Medicinal Products. *European Union herbal monograph on Paulliniae semen (Guarana)*. EMA/HMPC/897344/2011, 15 January 2013. - European Medicines Agency, Committee on Herbal Medicinal Products. *Assessment report on Paulliniae semen*. EMA/HMPC/897384/2011, 15 January 2013. - de Araujo DP, et al. (2021). The use of guarana (Paullinia cupana) as a dietary supplement for fatigue in cancer patients: a systematic review with a meta-analysis. *Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer*. PMID 34146166. - Maselli-Schoueri JH, et al. (2024). Natural supplementation to effectively treat cancer-induced fatigue: evidence of a meta-analysis on the use of guaraná. *Revista da Associacao Medica Brasileira (1992)*. PMID 39536249. - LiverTox: Clinical and Research Information on Drug-Induced Liver Injury, “Guarana.” National Institute of Diabetes and Digestive and Kidney Diseases, updated 2023. NCBI Bookshelf. --- *Guarana.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-16. The Thinking Press. https://thethinkingpress.org/materia-medica/guarana Historical description, not medical advice.