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Guarana: What It Is, How Much Caffeine It Has, and Is It Safe?
Guarana (Paullinia cupana) is a climbing plant from the Amazon whose seeds are among the richest natural sources of caffeine. It is used in energy drinks, Brazilian sodas and supplements sold for energy, focus and weight loss.
Last updated 2 November 2026
Guarana: the short answer
Guarana is an Amazon plant whose seeds contain up to about 6% caffeine. In a small 2007 trial, single doses of 37.5 to 300 mg of a guarana extract improved memory and alertness, and the authors judged that caffeine alone did not explain the effect. Its main risks are those of caffeine: the FDA says up to 400 mg of caffeine a day is not generally linked to harm in healthy adults, and guarana’s caffeine counts toward that total even when a label does not say how much there is.
| What it is | The seeds of Paullinia cupana, an Amazon climbing plant; one of the richest natural sources of caffeine, used in energy drinks and supplements. |
|---|---|
| Caffeine content | Up to about 6% caffeine in the seeds; labels often list guarana without stating the caffeine. |
| Most studied for | Alertness, mood and memory: one small trial of single doses found improvements not explained by caffeine alone. |
| Amounts used in studies | Single doses of 37.5 to 300 mg of a standardized extract. |
| Safety | The risks of caffeine: jitteriness, poor sleep, fast heartbeat. Count it toward the FDA’s 400 mg a day caffeine guide; take care with heart problems, high blood pressure or pregnancy. |
| In products we review | Audifort, ZenCortex, Sugar Defender |
Sources: Guarana: a highly caffeinated plant from the Amazon (Journal of Ethnopharmacology 2013) · Guarana extract, memory and mood: placebo-controlled trial (Journal of Psychopharmacology 2007) · How much caffeine is too much? (US FDA)
Benefits of Guarana
What is guarana?
Guarana, Paullinia cupana, is a climbing plant from the Amazon basin, grown mainly in the Brazilian states of Amazonas and Bahia. Its red fruits split open to show black seeds that look like eyes, and those seeds are roasted and ground into the powder and extracts used in drinks and supplements. About 70% of the harvest goes into soft drinks and energy drinks.
Why people take it
Guarana is valued as a stimulant because its seeds contain a lot of caffeine, up to about 6% by weight. Supplements use it for energy, focus, exercise and weight loss, and some products list it as a “natural” ingredient without saying that it supplies caffeine.
Top Rated Supplements with Guarana
Products we review that list Guarana as an ingredient. Not every product discloses how much of each ingredient a serving contains, so check each review before assuming it matches the amounts used in studies.
Audifort is a liquid dietary supplement marketed for hearing support and ringing in the ears, made from a blend of plant extracts, amino acids and a trace of chromium. This review looks at what is actually in the formula, what the evidence supports, what a realistic trial costs, and when hearing symptoms warrant an audiologist rather than a supplement.
ZenCortex is a liquid supplement marketed for hearing support, memory and mental sharpness. This liquid supplement is designed for individuals who are tired of the constant ringing, buzzing, or muffled sounds that often accompany aging or environmental exposure. In this review we look at the evidence behind the formula, which the vendor says contains over 20 ingredients, mostly plant extracts plus amino acids. ZenCortex comes as liquid drops rather than pills; there is no published evidence that this format is absorbed better. Whether you are looking to sharpen your mental focus or protect your delicate auditory system from oxidative stress, ZenCortex claims to provide the 360-degree support you need.
Sugar Defender is a liquid sold for blood sugar and weight loss. This review covers its full label, which turns out to be identical to ZenCortex’s, what research shows for chromium, gymnema, ginseng and the rest at the amounts in the drops, what people taking diabetes medicines should know, the real prices and the 60-day refund.
Scientific Analysis of Guarana
Energy, alertness and memory
In a double-blind, placebo-controlled trial published in 2007, 26 adults took single doses of 37.5, 75, 150 or 300 mg of a standardized guarana extract. Guarana improved memory test scores and made people feel more alert and content, and the two lower doses worked better than the higher ones. The authors concluded that caffeine alone could not explain the results. It was a small study of single doses, and it does not show what happens with daily use.
Weight loss and exercise
Guarana is common in weight-loss and pre-workout products, usually alongside other stimulants such as green tea or caffeine itself. Caffeine can slightly raise energy use and exercise performance, but we found no good evidence that guarana on its own leads to meaningful weight loss.
The caffeine in guarana
Because guarana seeds can contain up to about 6% caffeine, guarana counts toward your caffeine intake even when a label lists it as a plant extract. The US Food and Drug Administration says 400 mg of caffeine a day, roughly four or five cups of coffee, is an amount not generally linked to negative effects in healthy adults, and that toxic effects such as seizures can occur with rapid intake of around 1,200 mg. If you are pregnant, trying to become pregnant or breastfeeding, the FDA recommends asking your health care provider whether to limit caffeine.
Side effects and who should take care
Guarana’s side effects are those of caffeine: jitteriness, poor sleep, a fast heartbeat, anxiety, an upset stomach and headache, especially at higher intakes or when combined with coffee, energy drinks or other stimulants. People with heart rhythm problems, high blood pressure, anxiety or insomnia, and anyone sensitive to caffeine, should be cautious and ask a doctor first.
How much was used in studies
The 2007 trial used single doses of 37.5 to 300 mg of a standardized extract, with the lower doses giving the better results. Products differ widely in how much guarana and caffeine they contain, so check the label for the caffeine content where it is given.
Products we review that contain it
Audifort, ZenCortex and Sugar Defender each list guarana, along with green tea, in a blend of about 22 ingredients that totals 200 mg per 1 ml serving. None states the guarana or caffeine amount; with so small a blend the caffeine is probably modest, but it is worth knowing about if you are sensitive to caffeine, especially as some of these sellers describe their products as non-habit forming or stimulant-free.
Frequently Asked Questions
A climbing plant from the Amazon, Paullinia cupana, whose seeds are rich in caffeine. Its powder and extracts are used in energy drinks, Brazilian sodas and supplements.
Guarana seeds contain up to about 6% caffeine by weight. The amount in a drink or supplement depends on how much guarana it contains and how it is processed, and many labels do not state it.
Not quite. Caffeine is its main active compound, but guarana also contains other plant compounds, and in one small trial its effects on memory and alertness could not be explained by caffeine alone.
Like caffeine, it can increase alertness. In a 2007 trial, single doses of 37.5 to 300 mg of an extract improved memory and mood ratings. There is no good evidence that guarana on its own causes meaningful weight loss.
Its side effects are those of caffeine: jitteriness, poor sleep, fast heartbeat, anxiety, upset stomach and headache. Count its caffeine toward the FDA’s guide of 400 mg a day for healthy adults, and take care with heart problems, high blood pressure or other stimulants.
Guarana supplies caffeine, so ask your health care provider first. The FDA recommends that people who are pregnant, trying to become pregnant or breastfeeding talk to their provider about limiting caffeine.
Among the products we review, Audifort, ZenCortex and Sugar Defender list guarana with green tea in a 22-ingredient blend, without stating the amount of guarana or caffeine.
⚖️ Conclusion
Guarana is essentially a natural caffeine source with some extra plant compounds. A small trial suggests it can sharpen alertness and memory for a few hours, which is roughly what you would expect from caffeine, and there is no good evidence that it does much more, including for weight loss. The practical point is to count it: guarana adds caffeine even when a label calls it a plant extract, so people who are sensitive to caffeine, pregnant, or have heart problems or high blood pressure should check with a doctor and watch their total intake.