Guarana (Paullinia cupana): Uses, Evidence and Safety
Guarana seed (Paullinia cupana): a caffeine-rich herb. What research shows on focus and fatigue, and cautions for the heart, blood pressure, pregnancy, children and surgery.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read herb safety and interactions before you use anything on this page.
What is Guarana good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Thinking speed in healthy adults
Preliminary or mixedA 2023 meta-analysis of 8 small placebo-controlled studies found a small improvement in response time but not in accuracy, and no significant overall effect on cognition.
Supplements: Small effect on speed after single doses; chronic use and caffeine-matched comparisons not established.
Mental fatigue in healthy adults
Preliminary or mixedMemorial Sloan Kettering says guarana supplementation improved cognitive performance and mental fatigue in healthy adults.
Supplements: Possible short-term alertness effect, likely caffeine-related; evidence limited.
Cancer-related fatigue
Preliminary or mixedSmall studies suggest possible benefit, but others found no reduction in fatigue. A 2024 meta-analysis found a benefit (5 reports, 229 patients) while a 2026 review found no significant guarana effect and very low certainty.
Supplements: Not established; people with cancer should discuss any supplement with their care team.
Appetite, weight and sexual performance (promoted uses)
Preliminary or mixedGuarana is promoted to reduce hunger and improve sexual performance; Memorial Sloan Kettering notes these have not been studied for effectiveness. Small cancer studies hint at weight stability and appetite effects.
Supplements: No good evidence of benefit in the sources read.
Laboratory findings (antioxidant, neuroprotective, anxiolytic)
Lab or animal research onlyLaboratory studies suggest chemopreventive, neuroprotective, anxiolytic and antioxidant properties.
Supplements: No human benefit shown from these lab findings.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (4)
- Energy BoostPreliminary or mixed
Guarana contains caffeine, a stimulant. Small studies and meta-analyses of guarana suggest at most a small, short-term effect, probably through its caffeine; results for cancer-related fatigue conflict.
- Better FocusPreliminary or mixed
Caffeine-containing guarana may speed responses slightly; accuracy was not improved and the source of the effect is unknown.
- Cognitive PerformancePreliminary or mixed
A 2023 meta-analysis found a small gain in response time but no change in accuracy or overall cognition.
- Reduce FatiguePreliminary or mixed
Mental fatigue improved in healthy adults per Memorial Sloan Kettering; cancer-related fatigue results conflict.
Body systems (5)
- Cardiovascular SystemDocumented risk
Memorial Sloan Kettering warns guarana may cause irregular heartbeat and raise blood pressure.
- Heart & CirculationDocumented risk
Case reports describe fast heartbeat and extra heartbeats with guarana products.
- Nervous SystemDocumented risk
As a caffeine source guarana stimulates the central nervous system; insomnia and, at high amounts, seizures are reported.
- Brain & FocusPreliminary or mixed
Small effect on response time in healthy adults; no effect on accuracy.
- Energy & FatiguePreliminary or mixed
Small studies and meta-analyses of guarana suggest at most a small, short-term effect, probably through its caffeine; results for cancer-related fatigue conflict.
Body parts (3)
- HeartDocumented risk
Caffeine can speed the heart; case reports of rhythm effects with guarana products.
- BrainPreliminary or mixed
Caffeine-containing guarana had a small effect on thinking speed in healthy adults.
- Nervous SystemDocumented risk
Stimulant effects; seizures reported at high amounts or in energy-drink cases.
Functional actions (1)
- Cognitive EnhancementPreliminary or mixed
Small effect on response time only.
Root causes (1)
- Medication Side EffectsDocumented risk
Guarana may add to other stimulants, may raise bleeding risk with blood thinners (lab findings) and may lower amiodarone levels (rat study); clinical relevance is not known.
Documented risks and interactions (5)
- Caffeine effects on heart and blood pressure. Caffeine stimulates the heart and central nervous system and can raise blood pressure. Case reports describe fast heartbeat and extra heartbeats with guarana products.
- Insomnia, nausea and high-amount effects (vomiting, seizures). Common side effects are nausea and insomnia; at high amounts vomiting, heartbeat changes, high blood pressure and seizures. Seizures were reported in four young adults after an energy drink containing guarana and other ingredients.
- Interactions with stimulants, blood thinners and amiodarone. Combining with other stimulants may not be safe. Lab studies show antiplatelet activity, so bleeding risk with warfarin is possible. A rat study found lower amiodarone levels.
- Children and energy drinks. Medical experts advise against energy drinks for children and teens because of caffeine and sugar. Memorial Sloan Kettering describes vomiting, agitation, fast heartbeat or high blood pressure in children after misuse of supplements.
- Pregnancy and breastfeeding (caffeine). The FDA advises people who are pregnant, trying to become pregnant or breastfeeding to ask a provider whether to limit caffeine. Memorial Sloan Kettering does not address guarana in pregnancy.
Safety first: guarana is a caffeine product
The seeds contain caffeine, and Memorial Sloan Kettering says most of guarana's effects are put down to it. [1] That means the cautions for caffeine apply. Memorial Sloan Kettering lists nausea and insomnia as common side effects, and with high amounts vomiting, heartbeat changes, high blood pressure and seizures. [1] It also reports case reports of fast heartbeat in two women using guarana supplements or energy drinks, extra heartbeats in a woman with a heart valve condition, and seizures in four healthy young adults after an energy drink containing guarana and other ingredients. [1] It says combining guarana with other stimulants may not be safe, and that it may add to bleeding risk with blood thinners such as warfarin (lab findings; the real-world importance is not known). [1] The US Food and Drug Administration (FDA) notes that concentrated caffeine products can have serious consequences, including death, and that the label should list total caffeine from all sources. [2] Caffeine amounts in guarana products vary widely. [3] Tell your doctor or pharmacist about any guarana product, especially if you have a heart rhythm problem, high blood pressure, seizures, or are pregnant. See how herb and medicine interactions work and supplements before surgery.Overview
Guarana is the seed of Paullinia cupana, a climbing plant in the soapberry family (Sapindaceae). GBIF lists Paullinia cupana Kunth as the accepted name. [4] The Memorial Sloan Kettering page describes the seeds as containing caffeine and related chemicals. [1] The 2023 meta-analysis below notes that pure guarana can contain up to about 5.3% caffeine. [3] Guarana is sold as powder, capsules, extracts, and as an ingredient in energy drinks and "energy" supplements. Where its native range is concerned, the sources we read do not state it, so we do not give one here. This page covers the seed and its extracts. For another caffeine herb see green tea.Traditional use (not proof of benefit)
Memorial Sloan Kettering says traditional uses include fevers, headaches and dysentery, and that guarana is promoted to reduce hunger, manage fatigue, increase energy and improve sexual performance. [1] It adds that doctors have not studied several of these promoted uses for effectiveness. [1] Long use does not show that a product works or is safe.What research shows
Most human studies are small and many tested products where it is hard to tell guarana apart from its caffeine. [3]| Use | What the sources found | Strength of evidence | Form and population |
|---|---|---|---|
| Thinking speed and accuracy | A 2023 meta-analysis of 8 placebo-controlled studies (328 people) found no significant overall effect on cognition. Response time improved slightly, accuracy did not. The authors say it is unknown whether the effect comes from caffeine or other substances. [3] | Mixed (small effect on speed only) | Single doses; healthy adults |
| Mental fatigue in healthy adults | Memorial Sloan Kettering says guarana improved cognitive performance and mental fatigue in healthy adults. [1] | Promising but limited | Supplements; healthy adults |
| Cancer-related fatigue | Memorial Sloan Kettering reports small studies suggesting benefit, but also studies with no reduction in fatigue and a meta-analysis not better than placebo, rated low quality. [1] A 2024 meta-analysis of 5 reports (229 patients) found a benefit, with large differences between studies. [5] A 2026 meta-analysis of herbal products found no significant guarana effect and very low certainty. [6] | Mixed | Supplements; people with cancer |
| Weight loss and appetite | Memorial Sloan Kettering lists hunger reduction as a promoted use. [1] Proper evidence not found in the sources we read. | Insufficient evidence | Supplements |
| Sexual performance | Listed as a promoted use. [1] Proper evidence not found in the sources we read. | Insufficient evidence | Supplements |
| Anxiety, cancer prevention, brain protection | Memorial Sloan Kettering says these were seen only in laboratory studies. [1] | Lab findings only | Cells and animals |
Forms and why the form matters
Guarana is sold as seed powder, capsules, extracts, and inside energy drinks and mixed supplements. [1] The caffeine in guarana products varied widely in the studies reviewed (about 4 to 100 mg per study dose), and commercial products differ. [3] The meta-analysis found a larger speed effect with guarana dissolved in liquid than in capsules, but the difference was not statistically significant. [3] Energy drinks and mixed products add other stimulants or sugar, so results for guarana alone do not carry over. How much to use is a decision for a clinician or pharmacist, not this page.Safety in more detail
- Common side effects: nausea and insomnia; with higher amounts vomiting, heartbeat changes, high blood pressure and seizures. [1]
- Heart and blood pressure: Memorial Sloan Kettering warns guarana may cause irregular heartbeat and raise blood pressure. [1] See heart disease, blood pressure and supplements.
- Seizures: case reports exist after energy drinks containing guarana and other ingredients; the cause could not be pinned on guarana alone. [1] See epilepsy and seizure risk with herbs.
- Medicines: other stimulants; blood thinners such as warfarin (lab antiplatelet findings, importance not known); amiodarone (a rat study found lower blood levels, importance not known). [1]
- Pregnancy and breastfeeding: Memorial Sloan Kettering does not address this. [1] The FDA says people who are pregnant, trying to become pregnant or breastfeeding should ask their provider whether to limit caffeine. [2] See pregnancy and breastfeeding safety.
- Children and teens: medical experts advise against energy drinks for children and teens because of caffeine and sugar. [2] Memorial Sloan Kettering describes vomiting, agitation, fast heartbeat or high blood pressure in children after supplement misuse. [1]
- Liver and kidney: the sources we read give no liver or kidney warning. We could not read NIH's LiverTox (the site blocked access), so we make no claim either way.
- Surgery: Memorial Sloan Kettering does not address surgery. [1] Because of the bleeding and heart-rhythm concerns, tell the surgical team. See herbs before and after surgery.
- Allergy: the sources we read do not discuss allergy.
- Overall safety view: a 2019 review concluded guarana is not known to cause serious health risks when caffeine guidelines are respected. [7]
- Quality and contamination: the sources we read do not discuss guarana adulteration; caffeine content is the main variable. [3]
Official statements
- FDA (US), page current as of 28 August 2024: about 400 mg of caffeine a day is not generally linked to negative effects in healthy adults, sensitivity varies, and guarana is named as a caffeine source in energy drinks. [2]
- EU herbal monograph on guarana seed: we found the document (EMA/HMPC/897344/2011) but could not read its text, so we do not describe it.
- Memorial Sloan Kettering, page last updated 6 May 2022: summary of the evidence above. [1]
Related pages
Frequently asked questions
Does guarana give you energy?
Guarana contains caffeine, and most of its effects are credited to it. [1] A 2023 meta-analysis found a small effect on response time but not accuracy, and could not say whether caffeine or something else caused it. [3]
How much caffeine is in guarana?
It varies. Pure guarana can contain up to about 5.3% caffeine, and the products in the studies reviewed ranged from about 4 to 100 mg of caffeine per study dose. [3] Check the label for total caffeine. [2]
Is guarana safe?
A 2019 review found no serious risks when caffeine guidelines are followed. [7] Memorial Sloan Kettering still lists insomnia, nausea, heartbeat changes, raised blood pressure and, at high amounts, seizures. [1] Ask a clinician if you have heart, blood pressure or seizure problems.
Does guarana help with cancer fatigue?
Results conflict. A 2024 meta-analysis found a benefit, while a 2026 review found no significant effect and rated the evidence very low certainty. [5][6] Discuss it with your cancer care team.
Can I take guarana with blood thinners or other stimulants?
Memorial Sloan Kettering says other stimulants may not be safe with it and that it may raise bleeding risk with blood thinners. [1] Ask a pharmacist first.
References
- Memorial Sloan Kettering Cancer Center. Guarana: Purported Benefits, Side Effects & More. Page last updated 6 May 2022. Read 2026-10-23.
- U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine Is Too Much?. Content current as of 28 August 2024. Read 2026-10-23.
- Effect of Guarana (Paullinia cupana) on Cognitive Performance: A Systematic Review and Meta-Analysis. Nutrients, 2023. Read 2026-10-23.
- GBIF Secretariat. GBIF Backbone Taxonomy species match: Paullinia cupana Kunth. Read 2026-10-23.
- Natural supplementation to effectively treat cancer-induced fatigue: evidence of a meta-analysis on the use of guaraná. Revista da Associação Médica Brasileira, 2024. PMID 39536249. Europe PMC summary read 2026-10-23.
- Efficacy of Phytotherapy for Cancer-Related Fatigue: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Diseases, 2026. PMID 41745077. Europe PMC summary read 2026-10-23.
- Safety of Guarana Seed as a Dietary Ingredient: A Review. Journal of Agricultural and Food Chemistry, 2019. PMID 31539257. Europe PMC record read 2026-10-23.