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Limited evidenceBrain & cognition

Guayusa

An Amazonian holly leaf brewed as a caffeinated tea. Two small acute trials show the alertness effects you would expect from caffeine; the claim of a distinctively 'smoother' energy is not established.

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What the science says

  • Acute mood and cognitive performance Limited evidence

    A randomized dose-response trial of guayusa leaf extract in healthy adults found acute changes in mood and motor-cognitive performance along with the expected small cardiovascular effects. Effects were modest and the study tested a single session, not repeated use.

  • Compared with other stimulant extracts Limited evidence

    A randomized trial comparing acute guayusa tea and a lion's mane extract on cognitive performance in healthy adults reported small, task-specific effects. The design cannot separate guayusa's contribution from its caffeine content.

  • Safety and composition Limited evidence

    A critical review of guayusa's composition and history of use concluded that it is a caffeine-containing stimulant with an antioxidant profile similar to other Ilex species such as yerba mate, and that its safety record comes from traditional consumption rather than from trials.

Dosage & safety

Studied doseA cup of brewed guayusa provides roughly 50–90 mg of caffeine. Trials used single doses of leaf extract standardized for caffeine content. Treat total daily caffeine, not guayusa specifically, as the limit to watch.
SafetyThe main effects are those of caffeine: insomnia, jitteriness, palpitations, raised blood pressure and reflux, with tolerance and withdrawal headaches on regular use. Keep total caffeine below about 400 mg/day for healthy adults and 200 mg/day in pregnancy. Very hot beverage consumption of related Ilex teas has been associated in observational studies with oesophageal cancer risk — let it cool. Avoid if you have arrhythmia or uncontrolled hypertension.

How to take it

TimingMorning or early afternoon; caffeine has a half-life of about five hours, so avoid it within six hours of bed.
With food?Either way, though food softens the reflux some people get.
Worth knowingLet it cool before drinking — the oesophageal cancer signal in observational studies of related Ilex teas tracks drinking temperature, not the plant.

Interactions

With medications

  • ciprofloxacin, fluvoxamine and other CYP1A2 inhibitors (including oral contraceptives)

    They slow caffeine clearance, so the same cup hits harder and lasts much longer. cut your caffeine roughly in half while taking them

  • stimulant medication such as pseudoephedrine or ADHD drugs

    Additive jitteriness, raised heart rate and blood pressure. do not stack them; keep caffeine low on days you take a stimulant

With other supplements

  • other caffeine sources such as coffee, energy products, green tea extract or synephrine

    Caffeine adds up across products and the total is what causes insomnia and palpitations. count all sources against a 400 mg/day ceiling

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does guayusa give smoother energy than coffee?

That claim is not established. Guayusa is a caffeinated leaf, and small acute trials showed the modest alertness and mood effects expected from caffeine, so the evidence for anything beyond caffeine is limited.

How much caffeine is in guayusa?

A cup of brewed guayusa provides roughly 50-90 mg of caffeine. Count it with coffee and other sources toward a total of about 400 mg/day for healthy adults, or 200 mg/day in pregnancy.

Is guayusa safe?

Guayusa's side effects are those of caffeine: insomnia, jitteriness, palpitations, raised blood pressure and reflux. Avoid it with arrhythmia or uncontrolled hypertension, let it cool before drinking, and cut back if you take CYP1A2 inhibitors such as ciprofloxacin or fluvoxamine.

Scientific references

Related in Brain & cognition

Herbal medicines: what the evidence says (335)