Herb & supplement monograph

Guarana Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Guarana interacts with medications. The heart of this page is the interaction list — every drug Guarana is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Guarana is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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Guarana Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Because guarana contains caffeine, the overall risk of a clinically significant Guarana drug interaction is moderate for most people, and a few combinations deserve genuine caution. Only a handful of interactions are rated major, but the large majority are moderate, and nearly all trace back to the caffeine guarana contains.

Interactions deserving the most attention

The clearest concern is combining guarana with ephedrine or other stimulant medications, since caffeine plus a stimulant has been linked to serious problems like dangerously high blood pressure, heart attack, stroke, and seizures. Human evidence also shows that cimetidine, fluvoxamine, and estrogens slow the body's clearance of caffeine, so guarana's jittery, stimulant effects can build up. Caffeine may also raise clozapine levels and, in animal research, weaken several seizure medicines, so people taking these closely monitored drugs should treat guarana with extra care.

What the rest of the list means

A long interaction list does not mean every combination is harmful. Most entries are theoretical, based on how caffeine might affect enzymes the body uses to clear medications or on animal and lab findings, and several predicted effects have not been confirmed in people. In practice, many of these interactions come down to how much caffeine someone takes in overall.

Check your medications against Guarana

Based on HelloPharmacist’s Guarana interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Guarana

655 medications have a known interaction with Guarana, graded by severity. Select any drug for the full evidence-based detail.

8 major interactions. These combinations can be clinically significant — best avoided, or used only with close professional supervision. Always check with your pharmacist before combining them with Guarana.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Guarana using our pharmacist-reviewed interaction data.

AI summaries are generated from our Guarana interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Guarana combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Guarana affects

Every type of medication (drug category) Guarana is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 41 drug categories Guarana interacts with

EphedrineAdenosine (adenocard)Anticoagulant/antiplatelet DrugsBeta-adrenergic AgonistsCarbamazepine (tegretol)Cimetidine (tagamet)Clozapine (clozaril)Dipyridamole (persantine)Disulfiram (antabuse)Diuretic DrugsEstrogensEthosuximide (zarontin)Felbamate (felbatol)Flutamide (eulexin)Fluvoxamine (luvox)LithiumMonoamine Oxidase Inhibitors (maois)NicotinePentobarbital (nembutal)Phenobarbital (luminal)PhenylpropanolaminePhenytoin (dilantin)Pioglitazone (actos)Riluzole (rilutek)Stimulant DrugsTheophyllineValproateVerapamil (calan, Others)Alcohol (ethanol)Antidiabetes DrugsContraceptive DrugsCytochrome P450 1a2 (cyp1a2) InhibitorsFluconazole (diflucan)Metformin (glucophage)Methoxsalen (oxsoralen)Mexiletine (mexitil)PhenothiazinesQuinolone AntibioticsTerbinafine (lamisil)Tiagabine (gabitril)Ticlopidine (ticlid)

Ephedrine

Theoretically, concomitant use might increase the risk for stimulant adverse effects.
Guarana contains caffeine. Use of ephedrine with caffeine can increase the risk of stimulatory adverse effects. There is evidence that using ephedrine with caffeine might increase the risk of serious life-threatening or debilitating adverse effects such as hypertension, myocardial infarction, stroke, seizures, and death.

Likelihood Probable Evidence D

Adenosine (Adenocard)

Theoretically, guarana might decrease the vasodilatory effects of adenosine and interfere with its use prior to stress testing.
Guarana contains caffeine. Caffeine is a competitive inhibitor of adenosine at the cellular level. However, caffeine does not seem to affect supplemental adenosine because high interstitial levels of adenosine overcome the antagonistic effects of caffeine. It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests. However, methylxanthines appear more likely to interfere with dipyridamole (Persantine) than adenosine-induced stress testing.

Likelihood Possible Evidence B

Anticoagulant/Antiplatelet Drugs

Theoretically, guarana may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
In vitro and animal research suggests that guarana extract can inhibit platelet aggregation. This effect may be due to the caffeine in guarana, which is also reported to have antiplatelet activity. This interaction has not been reported in humans.

Likelihood Possible Evidence D

Beta-Adrenergic Agonists

Theoretically, concomitant use might increase the clinical effects of beta-adrenergic agonists.
Guarana contains caffeine. Theoretically, concomitant use of large amounts of caffeine might increase cardiac inotropic effects of beta-agonists.

Likelihood Probable Evidence D

Carbamazepine (Tegretol)

Theoretically, guarana might reduce the effects of carbamazepine and increase the risk for convulsions.
Animal research suggests that taking caffeine can lower the anticonvulsant effects of carbamazepine and can induce seizures when given to animals in doses above 400 mg/kg. Human research has shown that taking caffeine 300 mg in three divided doses along with carbamazepine 200 mg reduces the bioavailability of carbamazepine by 32% and prolongs the plasma half-life of carbamazepine two-fold in healthy individuals.

Likelihood Possible Evidence D

Cimetidine (Tagamet)

Theoretically, concomitant use might increase the effects and adverse effects of caffeine in guarana.
Guarana contains caffeine. Cimetidine decreases the rate of caffeine clearance by 31% to 42%.

Likelihood Likely Evidence B

Clozapine (Clozaril)

Theoretically, guarana might increase the levels and adverse effects of clozapine and acutely exacerbate psychotic symptoms.
Guarana contains caffeine. Caffeine can increase the effects and toxicity of clozapine. Caffeine doses of 400-1000 mg per day inhibit clozapine metabolism. Clozapine is metabolized by cytochrome P450 1A2 (CYP1A2). Researchers speculate that caffeine might inhibit CYP1A2. However, there is no reliable evidence that caffeine affects CYP1A2. There is also speculation that genetic factors might make some patients more sensitive to the interaction between clozapine and caffeine.

Likelihood Possible Evidence B

Dipyridamole (Persantine)

Theoretically, guarana might decrease the vasodilatory effects of dipyridamole and interfere with its use prior to stress testing.
Guarana contains caffeine. Caffeine might inhibit dipyridamole-induced vasodilation. It is recommended that methylxanthines and methylxanthine-containing products be stopped 24 hours prior to pharmacological stress tests. Methylxanthines appear more likely to interfere with dipyridamole than adenosine-induced stress testing.

Likelihood Probable Evidence B

Disulfiram (Antabuse)

Theoretically, disulfiram might increase the risk of adverse effects from caffeine.
In human research, disulfiram decreases the clearance and increases the half-life of caffeine.

Likelihood Probable Evidence D

Diuretic Drugs

Theoretically, using guarana with diuretic drugs might increase the risk of hypokalemia.
Guarana contains caffeine. Caffeine, especially in excessive amounts, can reduce potassium levels due to stimulation of the sodium-potassium pump. Diuretics can also lower potassium levels.

Likelihood Possible Evidence D

Estrogens

Theoretically, estrogens might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Estrogen inhibits caffeine metabolism.

Likelihood Probable Evidence B

Ethosuximide (Zarontin)

Theoretically, guarana might reduce the effects of ethosuximide and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine 92.4 mg/kg can decrease the anticonvulsant activity of ethosuximide. This effect has not been observed in humans.

Likelihood Possible Evidence D

Felbamate (Felbatol)

Theoretically, guarana might reduce the effects of felbamate and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that a high dose of caffeine 161.7 mg/kg can decreases the anticonvulsant activity of felbamate. This effect has not been observed in humans.

Likelihood Possible Evidence D

Flutamide (Eulexin)

Theoretically, guarana might increase the levels and adverse effects of flutamide.
Guarana contains caffeine. In vitro evidence shows that caffeine can inhibit the metabolism of flutamide. However, this effect has not been reported in humans.

Likelihood Probable Evidence D

Fluvoxamine (Luvox)

Theoretically, fluvoxamine might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Fluvoxamine reduces caffeine metabolism.

Likelihood Probable Evidence D

Lithium

Theoretically, abrupt guarana withdrawal might increase the levels and adverse effects of lithium.
Guarana contains caffeine. Theoretically, abrupt caffeine withdrawal might increase serum lithium levels. There are two case reports of lithium tremor that worsened upon abrupt coffee withdrawal.

Likelihood Probable Evidence D

Monoamine Oxidase Inhibitors (Maois)

Theoretically, concomitant use might increase the risk of a hypertensive crisis.
Guarana contains caffeine. Caffeine has been shown to inhibit MAO-A and -B in laboratory studies. Concomitant intake of large amounts of caffeine with MAOIs might precipitate a hypertensive crisis. In a case report, a patient that consumed 10-12 cups of caffeinated coffee and took the MAOI tranylcypromine presented with severe hypertension. Hypertension was resolved after the patient switched to drinking decaffeinated coffee.

Likelihood Possible Evidence D

Nicotine

Theoretically, concomitant use might increase the risk of hypertension.
Guarana contains caffeine. Concomitant use of caffeine and nicotine has been shown to have additive cardiovascular effects, including increased heart rate and blood pressure. Blood pressure was increased by 10.8/12.4 mmHg when the agents were used concomitantly.

Likelihood Probable Evidence D

Pentobarbital (Nembutal)

Theoretically, guarana might decrease the effects of pentobarbital.
Guarana contains caffeine. In vivo evidence suggests that caffeine can negate the hypnotic effects of pentobarbital in humans. However, animal research suggests that guarana does not alter the hypnotic effect of pentobarbital.

Likelihood Possible Evidence B

Phenobarbital (Luminal)

Theoretically, guarana might reduce the effects of phenobarbital and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of phenobarbital. The exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D

Phenylpropanolamine

Theoretically, phenylpropanolamine might increase the risk of hypertension, as well as the levels and adverse effects of caffeine.
Guarana contains caffeine. Concomitant use of phenylpropanolamine and caffeine might cause an additive increase in blood pressure. Phenylpropanolamine also seems to increase caffeine serum levels.

Likelihood Probable Evidence B

Phenytoin (Dilantin)

Theoretically, guarana might reduce the effects of phenytoin and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of phenytoin. The effect does not seem to be related to the seizure threshold-lowering effects of caffeine. However, the exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D

Pioglitazone (Actos)

Theoretically, guarana might increase the levels and clinical effects of pioglitazone.
Guarana contains caffeine. Animal research suggests that caffeine can modestly increase the maximum concentration, area under the curve, and half-life of pioglitazone, and also reduce its clearance. This increased the antidiabetic effects of pioglitazone. However, the exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D

Riluzole (Rilutek)

Theoretically, concomitant use might increase the levels and adverse effects of both caffeine and riluzole.
Guarana contains caffeine. Caffeine and riluzole are both metabolized by cytochrome P450 1A2 (CYP1A2), and concomitant use might reduce the metabolism of one or both agents.

Likelihood Possible Evidence D

Stimulant Drugs

Theoretically, concomitant use might increase stimulant adverse effects.
Guarana contains caffeine. Due to the central nervous system (CNS) stimulant effects of caffeine, concomitant use with stimulant drugs can increase the risk of adverse effects.

Likelihood Possible Evidence D

Theophylline

Theoretically, guarana might increase the levels and adverse effects of theophylline.
Guarana contains caffeine. Large amounts of caffeine might decrease theophylline clearance by 23% to 29%.

Likelihood Probable Evidence D

Valproate

Theoretically, guarana might reduce the effects of valproate and increase the risk for convulsions.
Guarana contains caffeine. Animal research shows that caffeine can decrease the anticonvulsant activity of valproate. The exact mechanism of this interaction is unclear.

Likelihood Possible Evidence D

Verapamil (Calan, Others)

Theoretically, verapamil might increase the levels and adverse effects of caffeine.
Verapamil increases plasma caffeine concentrations by 25%.

Likelihood Possible Evidence D

Alcohol (Ethanol)

Theoretically, alcohol might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Concomitant use of alcohol can increase caffeine serum concentrations and the risk of caffeine adverse effects. Alcohol reduces caffeine metabolism.

Likelihood Possible Evidence D

Antidiabetes Drugs

Theoretically, taking guarana with antidiabetes drugs might interfere with blood glucose control.
Some conflicting reports claim that caffeine, a constituent of guarana, might increase or decrease blood sugar.

Likelihood Unlikely Evidence B

Contraceptive Drugs

Theoretically, concomitant use might increase the effects and adverse effects of caffeine found in guarana.
Guarana contains caffeine. Oral contraceptives decrease the rate of caffeine clearance by 40% to 65%.

Likelihood Possible Evidence B

Cytochrome P450 1A2 (Cyp1A2) Inhibitors

Theoretically, concomitant use might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Caffeine is metabolized by the CYP1A2 enzyme. Theoretically, drugs that inhibit CYP1A2 may decrease the rate of caffeine clearance and increase caffeine levels.

Likelihood Possible Evidence D

Fluconazole (Diflucan)

Theoretically, fluconazole might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Fluconazole decreases caffeine clearance by approximately 25%.

Likelihood Possible Evidence B

Metformin (Glucophage)

Theoretically, metformin might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Animal research shows that metformin can reduce caffeine metabolism. However, this effect has not been reported in humans.

Likelihood Possible Evidence D

Methoxsalen (Oxsoralen)

Theoretically, methoxsalen might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Methoxsalen can reduce caffeine metabolism.

Likelihood Possible Evidence B

Mexiletine (Mexitil)

Theoretically, mexiletine might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Mexiletine can decrease caffeine elimination by 50%.

Likelihood Possible Evidence B

Phenothiazines

Theoretically, phenothiazines might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Phenothiazines can reduce the metabolism of caffeine by inhibiting cytochrome P450 1A2 (CYP1A2).

Likelihood Possible Evidence D

Quinolone Antibiotics

Theoretically, quinolone antibiotics might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Theoretically, concomitant use might increase serum caffeine concentrations and the risk of adverse effects. Quinolones (also called fluoroquinolones) can decrease caffeine clearance by inhibiting the cytochrome P450 1A2 enzyme.

Likelihood Possible Evidence B

Terbinafine (Lamisil)

Theoretically, terbinafine might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. Terbinafine decreases the clearance of intravenous caffeine by 19%.

Likelihood Possible Evidence B

Tiagabine (Gabitril)

Theoretically, guarana might increase the levels and adverse effects of tiagabine.
Guarana contains caffeine. Animal research shows that chronic caffeine administration can increase the serum concentrations of tiagabine. However, concomitant use does not seem to reduce the antiepileptic effects of tiagabine.

Likelihood Possible Evidence D

Ticlopidine (Ticlid)

Theoretically, ticlopidine might increase the levels and adverse effects of caffeine.
Guarana contains caffeine. In vitro evidence shows that ticlopidine can inhibit the metabolism of caffeine. However, this interaction has not been reported in humans.

Likelihood Possible Evidence D

Monograph

Guarana: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Guarana is an Amazonian seed that is naturally high in caffeine, which explains most of its stimulant and energy effects. While it may give a short-term boost in alertness and reduce fatigue, strong evidence for weight loss or major performance gains is limited, and it carries the same risks as too much caffeine. Talk to your pharmacist or doctor before using it, especially if you have heart problems, anxiety, or are pregnant.

Scientific name: Paullinia cupana
Family: Sapindaceae
Part used: Seeds
Common forms: Capsules, tablets, powders, energy drinks, liquid extracts

People commonly use it for

Energy and alertness
Reducing fatigue
Weight loss support
Athletic performance
Mental focus

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallUse caution

Generally tolerated in small amounts but it is high in caffeine, which can cause problems with overuse.

PregnancyPossibly Safe

When consumed in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored during pregnancy to ensur...

Read the full pregnancy detail

BreastfeedingPossibly Safe

When used orally in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored when breast-feeding. B...

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Guarana (Paullinia cupana) is a climbing plant native to the Amazon rainforest in Brazil and other parts of South America. The reddish fruit contains seeds that are dried, roasted, and ground into a powder that has been used for centuries by Indigenous Amazonian peoples as a stimulating drink and traditional remedy.

Today, guarana is best known as a natural source of caffeine. The seeds contain roughly 3% to 6% caffeine — often more than coffee beans by weight. Because of this, guarana is added to energy drinks, sodas, weight-loss products, and "energy" supplements. It is sold as capsules, tablets, powders, and liquid extracts.

How it works

The main active ingredient in guarana is caffeine (sometimes called "guaranine"). Caffeine blocks adenosine, a brain chemical that makes you feel sleepy, which is why it increases alertness and reduces the feeling of fatigue. It can also mildly raise heart rate and blood pressure and may speed up metabolism slightly.

Guarana seeds also contain other compounds such as tannins and small amounts of related stimulants like theobromine and theophylline. Some lab research suggests the tannins may slow how quickly the caffeine is released, possibly giving a longer-lasting effect, but this is not firmly proven in people. The plant also contains antioxidant compounds, though the health meaning of this is mostly based on laboratory studies.

Effectiveness

Does Guarana work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 14 uses evaluated

14 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Guarana, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 14 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Anxiety

Rating & evidence shown verbatim from Natural Medicines

Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Athletic performance

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for athletic performance.

Insufficient Reliable Evidence To Rate Cancer-related anorexia

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for anorexia in patients with cancer.

Insufficient Reliable Evidence To Rate Cancer-related fatigue

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for fatigue in patients with cancer.

Insufficient Reliable Evidence To Rate Chemotherapy-related fatigue

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for fatigue in patients receiving chemotherapy.

Insufficient Reliable Evidence To Rate Chronic fatigue syndrome (CFS)

Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral guarana for CFS, there is insufficient reliable information about the clinical effects of guarana for this condition.

Insufficient Reliable Evidence To Rate Cognitive function

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for improving cognitive function.

Insufficient Reliable Evidence To Rate Dysmenorrhea

Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral guarana for dysmenorrhea, there is insufficient reliable information about the clinical effects of guarana for this condition.

Insufficient Reliable Evidence To Rate Dyspepsia

Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral guarana for dyspepsia, there is insufficient reliable information about the clinical effects of guarana for this purpose.

Insufficient Reliable Evidence To Rate Erectile dysfunction (ED)

Rating & evidence shown verbatim from Natural Medicines

Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Headache

Rating & evidence shown verbatim from Natural Medicines

Although there has been interest in using oral guarana for headache, there is insufficient reliable information about the clinical effects of guarana for this purpose.

Insufficient Reliable Evidence To Rate Obesity

Rating & evidence shown verbatim from Natural Medicines

Oral guarana has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Insufficient Reliable Evidence To Rate Psychological well-being

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for improving feelings of well-being.

Insufficient Reliable Evidence To Rate Radiation-induced fatigue

Rating & evidence shown verbatim from Natural Medicines

It is unclear if oral guarana is beneficial for improving fatigue related to radiation therapy.

Source & disclaimer. Effectiveness ratings and evidence summaries are provided by Natural Medicines (Therapeutic Research Center) and shown as licensed. Where Natural Medicines hasn’t rated a use, HelloPharmacist’s pharmacists may add their own reviewed rating and evidence (each such entry is labeled). This is educational information, not medical advice — talk with your pharmacist or doctor before starting, stopping, or changing a supplement.

Safety & precautions

For most healthy adults, guarana in small amounts is generally tolerated, but its high caffeine content is the main safety concern. The amount of caffeine in different products can vary a lot, and it adds to any other caffeine you get from coffee, tea, soda, or other supplements.

Use caution or avoid guarana if you have heart problems, high blood pressure, irregular heartbeat, anxiety, sleep problems, or are sensitive to caffeine. It is not recommended for children and teens.

Pregnancy: It is best to avoid guarana while pregnant because of its high caffeine content, which is linked to risks when caffeine intake is high. Breastfeeding: Caffeine passes into breast milk and can affect a nursing baby, so guarana is best avoided or strictly limited. When in doubt, check with your doctor or pharmacist.

Side effects

Most side effects are the same as those from too much caffeine. These can include jitteriness, nervousness, a fast or pounding heartbeat, trouble sleeping, headache, upset stomach, and increased urination.

Higher doses can cause anxiety, restlessness, increased blood pressure, and heart rhythm changes. Very large amounts of caffeine — especially from concentrated supplements or energy products combined with other stimulants — can be dangerous and, in rare cases, lead to serious heart problems. Stop using it and seek medical care if you feel chest pain, a racing or irregular heartbeat, or severe anxiety.

Guarana: Reported Adverse Effects

Documented safety reports on Guarana from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, guarana is typically well tolerated when used in moderation. Due to its caffeine content, use of large doses may be unsafe.

Most Common Adverse Effects:

Orally: Stomach burning and nausea.

Reports by condition

Allergic rhinitis (hay fever) Immunologic

Guarana contains caffeine. When taken orally, caffeine can cause anaphylaxis in sensitive individuals, although true IgE-mediated caffeine allergy seems to be relatively rare.

Infante S, Baeza ML, Calvo M, et al. Anaphylaxis due to caffeine. Allergy 2003;58:681-2.

Anxiety Neurologic/CNS

Orally, guarana can cause dizziness. The caffeine in guarana can cause insomnia (especially in children), nervousness, restlessness, dizziness, tremors, delirium, and convulsions. Other symptoms include headache, anxiety, and agitation.

Taking guarana with ephedra can cause insomnia, irritability, dizziness, and headache. The combination of ephedra and caffeine in guarana might also increase the risk of adverse effects such as jitteriness, seizures, and temporary loss of consciousness.

del Giglio AB, Cubero Dde I, Lerner TG, Guariento RT, de Azevedo RG, Paiva H, Goldman C, Carelli B, Cruz FM, Schindler F, Pianowski L, de Matos LL, del Giglio A. Purified dry extract of Paullinia cupana (guaraná) (PC-18) for chemotherapy-related fatigue i
Schechter MD, Timmons GD. Objectively measured hyperactivity--II. Caffeine and amphetamine effects. J Clin Pharmacol 1985;25:276-80..
Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html.
Holmgren P, Norden-Pettersson L, Ahlner J. Caffeine fatalities--four case reports. Forensic Sci Int 2004;139:71-3.
Leson CL, McGuigan MA, Bryson SM. Caffeine overdose in an adolescent male. J Toxicol Clin Toxicol 1988;26:407-15.
de Araujo DP, Pereira PTVT, Fontes AJC, et al. The use of guarana (Paullinia cupana) as a dietary supplement for fatigue in cancer patients: a systematic review with a meta-analysis. Support Care Cancer 2021;29(12):7171-7182.
Boozer CN, Nasser JA, Heymsfield SB, et al. An herbal supplement containing Ma Huang-Guarana for weight loss: a randomized, double-blind trial. Int J Obes Relat Metab Disord 2001;25:316-24.
FDA. Proposed rule: dietary supplements containing ephedrine alkaloids. Available at: www.verity.fda.gov (Accessed 25 January 2000).
Spinella M. Herbal Medicines and Epilepsy: The Potential for Benefit and Adverse Effects. Epilepsy Behav 2001;2(6):524-532.

Anxiety Other

Guarana contains caffeine. The existence or clinical importance of caffeine withdrawal is controversial. Some researchers think that if it exists, it appears to be of little clinical significance. Other researchers suggest symptoms such as headache; tiredness and fatigue; decreased energy, alertness, and attentiveness; drowsiness; decreased contentedness; depressed mood; difficulty concentrating; irritability; and lack of clear-headedness are typical of caffeine withdrawal. Withdrawal symptoms such as delirium, nausea, vomiting, rhinorrhea, nervousness, restlessness, anxiety, muscle tension, muscle pains, and flushed face have been described. However, these symptoms may be from nonpharmacological factors related to knowledge and expectation of effects. Clinically significant symptoms caused by caffeine withdrawal may be uncommon.

Bone loss Musculoskeletal

In a clinical trial of guarana extract, one person abandoned treatment due to symptoms of arthritis with edema. It is not clear if this adverse effect is due to guarana.

Cases of rhabdomyolysis and myoglobinuria have been reported in individuals that have taken products containing guarana in combination with ephedra and other herbal products. These adverse effects are thought to be related to the caffeine content of guarana.

Epidemiological evidence regarding the relationship between caffeine use and the risk for osteoporosis is contradictory. Caffeine can increase urinary excretion of calcium. Women identified with a genetic variant of the vitamin D receptor appear to be at an increased risk for the detrimental effect of caffeine on bone mass. However, moderate caffeine intake, less than 300 mg per day, does not seem to significantly increase osteoporosis risk in most postmenopausal women with normal calcium intake.

Breast cancer Endocrine

Guarana contains caffeine. Some evidence shows caffeine is associated with fibrocystic breast disease, breast cancer, and endometriosis; however, this is controversial since findings are conflicting. Restricting caffeine in people with fibrocystic breast conditions doesn't seem to affect breast nodularity, swelling, or pain. A population analysis of the Women's Health Initiative observational study has found no association between consumption of caffeine-containing beverages and the incidence of invasive breast cancer in models adjusted for demographic, lifestyle, and reproductive factors. Also, a dose-response analysis of 2 low-quality observational studies has found that high consumption of caffeine is not associated with an increased risk of breast cancer.

Although the effects of guarana alone are not clear, the combination of guarana along with ephedra has been reported to cause increased blood glucose levels and decreased blood levels of potassium.

Depression Psychiatric

In a clinical trial, depression was reported by one person taking guarana extract.

del Giglio AB, Cubero Dde I, Lerner TG, Guariento RT, de Azevedo RG, Paiva H, Goldman C, Carelli B, Cruz FM, Schindler F, Pianowski L, de Matos LL, del Giglio A. Purified dry extract of Paullinia cupana (guaraná) (PC-18) for chemotherapy-related fatigue i

Hypertension Cardiovascular

Orally, a case of premature ventricular contraction has been reported for a 51-year-old female who used guarana as part of a multi-ingredient herbal product.

Guarana contains caffeine. Although acute administration of caffeine can increase blood pressure, regular consumption does not seem to increase either blood pressure or pulse, even in mildly hypertensive patients. Also, epidemiological research suggests there is no association between caffeine consumption and increased incidence of hypertension. Habitual coffee consumption doesn't seem to be related to hypertension, but habitual consumption of sugared or diet cola is associated with development of hypertension.

Combining ephedra with guarana can increase the risk of adverse effects. Cases of hypertension and chest pain have been reported for patients who took products containing guarana and ephedra. A case of cerebral infarction has also been reported for a patient consuming ephedra extract and guarana. There is also a report of ischemic stroke in an athlete who consumed ephedra 40-60 mg, creatine monohydrate 6 grams, caffeine 400-600 mg, and a variety of other supplements daily for six weeks.

Nausea and vomiting Gastrointestinal

Orally, guarana can cause a sensation of burning in the stomach and vomiting. These effects may be due to caffeine in guarana. Orally, caffeine can cause gastric irritation, nausea, and vomiting. In infants, caffeine may also cause feeding intolerance and gastrointestinal irritation.

Galduroz, J. C. and Carlini, E. A. The effects of long-term administration of guarana on the cognition of normal, elderly volunteers. Sao Paulo Med.J. 1996;114(1):1073-1078.
Palma CG, Lera AT, Lerner T, de Oliveira MM, de Borta TM, Barbosa RP, Brito GM, Guazzelli CA, Cruz FJ, del Giglio A. Guarana (Paullinia cupana) Improves Anorexia in Patients with Advanced Cancer. J Diet Suppl. 2016;13(2):221-31.
Institute of Medicine. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations. Washington, DC: National Academy Press, 2001. Available at: http://books.nap.edu/books/0309082587/html/index.html.
Holmgren P, Norden-Pettersson L, Ahlner J. Caffeine fatalities--four case reports. Forensic Sci Int 2004;139:71-3.
Leson CL, McGuigan MA, Bryson SM. Caffeine overdose in an adolescent male. J Toxicol Clin Toxicol 1988;26:407-15.
Tobias JD. Caffeine in the treatment of apnea associated with respiratory syncytial virus infection in neonates and infants. South Med J 2000;93:297-304.

Urticaria Dermatologic

Guarana contains caffeine. There are several case reports of urticaria after caffeine ingestion.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

Dosing

There is no official standardized dose for guarana. The caffeine content varies widely between products, so the strength of one supplement may be very different from another.

The safest approach is to follow the directions on the product label and to count guarana toward your total daily caffeine intake from all sources. If you are unsure how much caffeine a product contains or whether it is safe for you, ask your pharmacist or doctor before taking it. Avoid combining several caffeine-containing products at once.

Pregnancy & Breastfeeding

Guarana & Pregnancy

Possibly Safe

When consumed in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored during pregnancy to ensure moderate consumption. Although it is not considered a teratogen, caffeine crosses the placenta and causes dose-dependent increases in fetal blood concentrations. The use of caffeine during pregnancy is controversial; however, moderate consumption has not been associated with clinically important adverse fetal effects. In some studies, consuming amounts over 200 mg daily is associated with a significantly increased risk of miscarriage. This increased risk may be most likely to occur in individuals with genotypes that confer a slow rate of caffeine metabolism. According to a review by Health Canada, and a subsequent large meta-analysis conducted in the US, caffeine can be safely consumed in doses up to 300 mg daily without an increased risk of spontaneous abortion, stillbirth, preterm birth, fetal growth retardation, or congenital malformations. However, some research has also found that intrauterine exposure to even modest amounts of caffeine, based on maternal blood levels during the first trimester, is associated with a shorter stature in children ages 4-8 years. Advise individuals to keep caffeine consumption below 300 mg daily during pregnancy.

Briggs GB, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 1998.
The National Toxicology Program (NTP). Caffeine. Center for the Evaluation of Risks to Human Reproduction (CERHR). Available at: http://cerhr.niehs.nih.gov/common/caffeine.html.
Klebanoff MA, Levine RJ, DerSimonian R, et al. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. N Engl J Med 1999;341:1639-44.
Eskenazi B. Caffeine—filtering the facts. N Engl J Med 1999;341:1688-9.
Fernandes O, Sabharwal M, Smiley T, et al. Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis. Reprod Toxicol 1998;12:435-44.
Bracken MB, Triche EW, Belanger K, et al. Association of maternal caffeine consumption with decrements in fetal growth. Am J Epidemiol 2003;157:456-66..
Nawrot P, Jordan S, Eastwood J, et al. Effects of caffeine on human health. Food Addit Contam 2003;20:1-30.
Weng X, Odouli R, Li DK. Maternal caffeine consumption during pregnancy and the risk of miscarriage: a prospective cohort study. Am J Obstet Gynecol 2008;198:279.e1-8.
Savitz DA, Chan RL, Herring AH, et al. Caffeine and miscarriage risk. Epidemiology 2008;19:55-62.
Wikoff D, Welsh BT, Henderson R, et al. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children. Food Chem Toxicol 2017;109:585-648.
Gleason JL, Sundaram R, Mitro SD, et al. Association of maternal caffeine consumption during pregnancy with child growth. JAMA Netw Open. 2022;5(10):e2239609.

Possibly Unsafe

When used orally in amounts over 300 mg daily. Although it is not considered a teratogen, caffeine crosses the placenta and causes dose-dependent increases in fetal blood concentrations. Consumption of caffeine in amounts over 300 mg daily is associated with a significantly increased risk of miscarriage in some studies. Advise keeping caffeine consumption from all sources below 300 mg daily. High maternal doses of caffeine throughout pregnancy have resulted in symptoms of caffeine withdrawal in newborn infants. High doses of caffeine have also been associated with spontaneous abortion, premature delivery, and low birth weight.

Guarana & Breastfeeding

Possibly Safe

When used orally in amounts commonly found in foods. Due to the caffeine content of guarana, intake should be closely monitored when breast-feeding. Breast milk concentrations of caffeine are thought to be approximately 50% of serum concentrations.

Nehlig A, Debry G. Consequences on the newborn of chronic maternal consumption of coffee during gestation and lactation: a review. J Am Coll Nutr 1994;13:6-21..

Possibly Unsafe

When used orally in large amounts. Consumption of guarana might cause irritability and increased bowel activity in nursing infants. Large doses or excessive intake of guarana should be avoided when breast-feeding.

American Academy of Pediatrics. The transfer of drugs and other chemicals into human milk. Pediatrics 2001;108:776-89.

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

The 114 references that drive our Guarana monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

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Klebanoff MA, Levine RJ, DerSimonian R, et al. Maternal serum paraxanthine, a caffeine metabolite, and the risk of spontaneous abortion. N Engl J Med 1999;341:1639-44. PubMed
Eskenazi B. Caffeine—filtering the facts. N Engl J Med 1999;341:1688-9. PubMed
Fernandes O, Sabharwal M, Smiley T, et al. Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis. Reprod Toxicol 1998;12:435-44. PubMed
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del Giglio AB, Cubero Dde I, Lerner TG, Guariento RT, de Azevedo RG, Paiva H, Goldman C, Carelli B, Cruz FM, Schindler F, Pianowski L, de Matos LL, del Giglio A. Purified dry extract of Paullinia cupana (guaraná) (PC-18) for chemotherapy-related fatigue i
Palma CG, Lera AT, Lerner T, de Oliveira MM, de Borta TM, Barbosa RP, Brito GM, Guazzelli CA, Cruz FJ, del Giglio A. Guarana (Paullinia cupana) Improves Anorexia in Patients with Advanced Cancer. J Diet Suppl. 2016;13(2):221-31.
Wikoff D, Welsh BT, Henderson R, et al. Systematic review of the potential adverse effects of caffeine consumption in healthy adults, pregnant women, adolescents, and children. Food Chem Toxicol 2017;109:585-648. PubMed
de Araujo DP, Pereira PTVT, Fontes AJC, et al. The use of guarana (Paullinia cupana) as a dietary supplement for fatigue in cancer patients: a systematic review with a meta-analysis. Support Care Cancer 2021;29(12):7171-7182. PubMed
Zheng KH, Zhu K, Wactawski-Wende J, et al. Caffeine intake from coffee and tea and invasive breast cancer incidence among postmenopausal women in the Women's Health Initiative. Int J Cancer 2021;149(12):2032-2044. PubMed
Wang S, Li X, Yang Y, et al. Does coffee, tea and caffeine consumption reduce the risk of incident breast cancer? A systematic review and network meta-analysis. Public Health Nutr 2021;24(18):6377-6389. PubMed
Alshabi AM, Alkahtani SA, Shaikh IA, Habeeb MS. Caffeine modulates pharmacokinetic and pharmacodynamic profiles of pioglitazone in diabetic rats: Impact on therapeutics. Saudi Med J 2021;42(2):151-160. PubMed
Gleason JL, Sundaram R, Mitro SD, et al. Association of maternal caffeine consumption during pregnancy with child growth. JAMA Netw Open. 2022;5(10):e2239609. PubMed

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

Brand directory

Brands that make products with Guarana

473 brands in our database make a supplement containing Guarana.

'Merica Energy 1 product 1st Phorm 75 products 2 Own the Knight 1 product 21st Century 798 products 24 Bio 11 products 3D Energy Drinks 4 products 4 Organics 16 products A.B.B. American Body Building 55 products AA Anabolic Agents 16 products ABB Performance 22 products About Time 27 products Absolute Nutrition 15 products Accelerated Intelligence 1 product Accelerated Sport Nutraceuticals 2 products Accomplix 6 products Addrena 9 products Advanced Nutrition by Zahler 135 products Advocare 165 products ALLMAX 210 products ALLMAX NUTRITION 24 products Aloe Life 5 products Alpha Base 1 product Alpha Pro Nutrition 1 product Altrum 113 products

Product directory

Supplement products with Guarana

1,453 products in our database contain Guarana. Open any to see its full ingredient list and every drug interaction we check.

Pharmacist Counseling Corner

Guarana: Common Questions

What is Guarana used for, and does it work?

People use Guarana for a range of reasons, but according to the Natural Medicines database the current clinical evidence is insufficient to confirm it works for the specific conditions it has been studied for. See the graded list on this page, and talk to your pharmacist or doctor before relying on it for any condition.

Does Guarana interact with prescription medications?

Yes. We list 655 medications with a known interaction with Guarana, including 8 rated major. Use the checker above to see how Guarana interacts with a specific drug.

How are Guarana interactions rated?

Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.

Is it safe to take Guarana with my medications?

It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.

Where does this Guarana interaction information come from?

Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.

What is Guarana used for?

People most often use Guarana to boost energy, stay alert, reduce tiredness, and support focus. It is also a common ingredient in weight-loss and "energy" products, though strong proof for weight loss is lacking.

Does Guarana have caffeine?

Yes. Guarana seeds are naturally very high in caffeine — often more than coffee beans by weight — which explains most of its stimulant effects.

Is Guarana safe to take?

In small amounts it is generally tolerated by healthy adults, but because it is high in caffeine it can cause jitteriness, a fast heartbeat, and sleep problems, and it may not be safe for people with heart conditions or anxiety.

Can I take Guarana while pregnant or breastfeeding?

It is best to avoid Guarana during pregnancy because of its high caffeine content, and to avoid or strictly limit it while breastfeeding since caffeine passes into breast milk. Check with your doctor first.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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Guarana Drug Interactions, Uses, Effectiveness, Safety & More

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Guarana Drug Interactions: The Bottom Line

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What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

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Guarana: Uses, Safety & Side Effects

Overview

How it works

Does Guarana work?

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Guarana: Reported Adverse Effects

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Guarana & Pregnancy

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