The short answer
Guarana can contribute substantial caffeine, so check with your prescriber before taking it with phenelzine. The concern is a potentially excessive stimulant load and a rise in blood pressure. The amount and other ingredients matter more than the word "natural" on the package.
What this answer covers
Oral Paullinia cupana seed preparations that contain caffeine. No assumption is made about the caffeine concentration of an unidentified brand, a different plant part or a caffeine-free preparation.
- Supplement or preparation
- Paullinia cupana
- Medication ingredient
- phenelzine
Guarana counts as caffeine
Some labels list guarana rather than listing a separate caffeine quantity. This does not make the product stimulant-free. Include it when describing coffee, tea, energy drinks and pre-workout products to your pharmacist.
What is known about this combination
Phenelzine carries a warning about excessive caffeine. That supports caution with caffeine-containing guarana, but it does not establish a clinical event rate for every guarana extract or dose.
Combination products add uncertainty
A product may also contain added caffeine or other stimulants. Information about one ingredient cannot clear the whole formulation for use. Bring the complete supplement label, including serving size, for review.
Avoid relying on a timing gap
There is no validated hours-apart schedule that makes a high caffeine exposure safe with this MAOI. Follow a prescriber-agreed plan and seek urgent care for a sudden severe headache, chest pain or severe blood-pressure symptoms.
Evidence and practical considerations
Side effects & toxicity
Guarana is a botanical caffeine source. Applying the phenelzine warning about excessive caffeine to caffeine-containing guarana is a constituent-based inference; no exact guarana-pair clinical trial was identified.
- Exact scope
- Oral Paullinia cupana seed preparations that contain caffeine. No assumption is made about the caffeine concentration of an unidentified brand, a different plant part or a caffeine-free preparation. with Oral phenelzine tablets; current sulfate-tablet labeling uses the named active ingredient.
- Medication form and route
- oral
What remains uncertain
- Caffeine may be incompletely stated on labels. Direct guarana-MAOI outcome data and a safe dose threshold are lacking.
Factors that may matter: Exact supplement preparation and complete concomitant-medication list require assessment..
Read the supporting source summaries
Source 1: Current U.S. prescribing information
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral phenelzine sulfate tablets.
The label prohibits sympathomimetics, L-tryptophan, L-tyrosine, phenylalanine and serotonergic agents. It warns about excessive caffeine and high-tyramine exposures.
How this applies: Primary authority for phenelzine oral-tablet precautions; each article identifies whether the supplement is named or the application is a constituent/class inference.
Regulatory instructions do not quantify an exact-pair event rate or validate every botanical formulation.
Source 2: Federal ingredient information
ods.od.nih.gov · Source check Sep 10, 2026
Population: Consumers of caffeine and botanical dietary supplements.
Guarana and tea can contribute caffeine, and a botanical ingredient list may omit the amount of caffeine. Caffeine has stimulant effects.
How this applies: General healthy-adult caffeine limits are not safety limits for patients receiving MAOIs. No exact guarana-MAOI trial is supplied.
General healthy-adult caffeine limits are not safety limits for patients receiving MAOIs. No exact guarana-MAOI trial is supplied.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Initial targeted research draft. Inspected source material, adjudicated the current checker statements, and recorded preparation limits. Clinical review has not occurred. | |
| Research summary published |
Article revision: 7ec5a2b8cee297ea
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.