Guarana: Caffeine Content, Benefits, Side Effects and Label Tips

Guarana is a climbing plant from the Amazon whose seeds are one of the richest natural sources of caffeine, with reported levels of about 2% to 7.5% of the seed’s weight. In energy drinks and weight-loss supplements, guarana works mainly as a caffeine source, so its effects and risks largely follow caffeine’s. Small studies suggest a single serving can sharpen attention and alertness, but evidence beyond that is thin. The practical issue is hidden caffeine: a label may list guarana without saying how much caffeine it adds. Here is what guarana is, how guarana caffeine compares with coffee caffeine, what the research shows and who should be careful.

Peptide Labs sells supplements that contain guarana, but this article does not recommend any of them. It is general information, not medical advice.

What is guarana?

Guarana, Paullinia cupana, belongs to the soapberry family (Sapindaceae). A 2019 safety review by US Pharmacopeia experts notes that its seeds have long been used as a stimulant and today are ground into powder and sold as powder, tablets and capsules. Researchers Nigel Smith and Andre Atroch write that guarana was domesticated in the Brazilian Amazon; it is unclear by which group, but the Satere-Maue people along the Maues River cultivate it extensively. Carbonated guarana soda reached Brazilians in 1909 and became a national drink.

Brazil remains the main producer. A 2013 review in the Journal of Ethnopharmacology says guarana is grown mainly in the states of Amazonas and Bahia and that about 70% of the harvest goes to soft drink and energy drink makers. The rest becomes powder for capsules or for mixing with water, or raw material for drug and cosmetic companies.

Guarana caffeine: how much does it contain?

Smith and Atroch report caffeine levels of 2% to 7.5% in guarana seeds and estimate that guarana has about four times as much caffeine as coffee. The 2013 review gives up to 6%. One weight-loss trial described by the ODS used guarana with 3% to 6% caffeine. Extracts can be more concentrated: one research extract was standardized to about 12% caffeine. That variation is why the amount of guarana on a label tells you little unless the caffeine is stated too.

Guarana vs caffeine: is there a difference?

Chemically, no. “Guaranine”, the name once given to the stimulant in guarana, is listed in the NIH’s PubChem database as a synonym for caffeine (1,3,7-trimethylxanthine). The molecule is identical whether it comes from a guarana seed, a coffee bean or a factory.

Guarana seeds do contain other compounds; Memorial Sloan Kettering notes they hold caffeine and other caffeine-like chemicals. Two small studies from one UK research group suggested guarana’s effects on attention and memory were not fully explained by its caffeine. For safety, though, count caffeine from guarana the same way as caffeine from coffee.

Guarana benefits: what studies show

In a 2004 placebo-controlled study at Northumbria University, 28 healthy adults aged 18 to 24 took single servings of a guarana extract. Performance improved on attention tasks, though with some evidence of reduced accuracy, and on serial subtraction. A 2007 study from the same group tested four amounts in 26 adults and found better memory and higher alertness and contentment ratings, with the two lower amounts giving the more positive results. Neither study looked at regular use over weeks or months.

For weight, the ODS describes a trial in which 47 adults with overweight took a combination of yerba mate, guarana and damiana before meals for 45 days and lost an average of 5.1 kg, compared with 0.3 kg on placebo. It was small, short and tested a blend. The ODS concludes that caffeine might help people lose a little weight or gain less over time, but that tolerance can blunt the effect. Our review of whether fat burners work looks at caffeine-based formulas in more detail.

Hidden caffeine: reading labels that list guarana

The FDA requires packaged foods to list caffeine in the ingredients when it is added on its own, but when caffeine comes naturally from an ingredient, only that ingredient may appear. The ODS warns that some weight-loss supplement labels do not declare the amount of caffeine and list only the herbs, so buyers may not realize a product contains it. For most adults, the FDA cites 400 milligrams of caffeine a day as an amount not generally associated with negative effects, and caffeine from guarana counts toward it. Our guide to how much caffeine is too much shows how quickly coffee, tea and supplements add up. Three products we carry show why the whole panel matters:

You can read the full labels on our pages for Animal Cuts, Zantrex Blue and JetFuel Original. All three say they are not for anyone under 18 or for use during pregnancy or nursing, and the Animal Cuts and Zantrex Blue labels tell users to avoid or limit other caffeine. JetFuel also lists yohimbe bark extract; read our article on yohimbine and yohimbe safety before considering any product that contains it.

Energy drinks, guarana and emergency visits

A 2013 federal report from the Substance Abuse and Mental Health Services Administration (SAMHSA) described energy drinks as high in caffeine and often containing guarana, “a plant product containing concentrated caffeine.” Emergency department visits involving energy drinks doubled from 10,068 in 2007 to 20,783 in 2011, and 58% of the 2011 visits involved energy drinks alone. The report notes that large amounts of caffeine can cause insomnia, nervousness, headache, fast heartbeat and seizures. Memorial Sloan Kettering lists case reports of fast heart rate in women taking guarana supplements and seizures in healthy young adults after energy drinks containing guarana. The American Academy of Pediatrics says the caffeine and other stimulants in energy drinks have no place in the diets of children and teens.

Side effects, interactions and who should avoid guarana

Memorial Sloan Kettering lists nausea and trouble sleeping as common side effects, and vomiting, heartbeat changes, high blood pressure and seizures at high intakes. The FDA’s list for too much caffeine adds palpitations, anxiety, jitters, upset stomach and headache. Talk to a clinician first if any of these apply:

• Blood thinners such as warfarin: Memorial Sloan Kettering says guarana may increase bleeding risk.
• Amiodarone or other heart rhythm medicines: a possible interaction is listed.
• Ciprofloxacin: MedlinePlus advises against consuming a lot of caffeine, because the antibiotic may intensify its effects.
• Other stimulants: caffeine pills, bitter orange and yohimbe add to guarana’s effects.
• Pregnancy or breastfeeding: the FDA suggests asking your provider whether to limit caffeine, and the products above say not to use them.
• Heart conditions, high blood pressure, anxiety or reflux: caffeine can raise heart rate and blood pressure, and NIDDK lists caffeine among triggers for acid reflux.

The 2019 US Pharmacopeia review concluded that guarana is not known to cause serious harm when used properly and that risks are unlikely if caffeine intake guidelines are respected. Seek emergency care for chest pain, a racing or irregular heartbeat, fainting or a seizure.

Frequently Asked Questions

Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Last reviewed September 2026.

Related guides: How Much Caffeine Is Too Much? Daily Limits, Overdose Signs and Label Math, Do Fat Burners Work? Thermogenic Ingredients, Evidence and Risks, Yohimbine: Yohimbe vs Yohimbine HCl, Fat Loss Evidence and Side Effects, Caffeine Pills: Caffeine Anhydrous, Tablets vs Coffee and Safety.