The short answer
No study of guarana with linezolid was found, and the linezolid label's blood pressure warning concerns ephedrine-type stimulants, not caffeine. Guarana is a concentrated caffeine source whose content often exceeds the label. During a linezolid course it is reasonable to limit stimulant supplements and follow the label's blood pressure monitoring advice if you have high blood pressure, but an interaction has not been demonstrated.
What this answer covers
Guarana (Paullinia cupana) seed extracts and powders used for their caffeine, with linezolid by any route. Product caffeine content varies.
- Supplement or preparation
- guarana
- Medication ingredient
- linezolid
What the label covers
Linezolid is a reversible MAO inhibitor. Its label warns of enhanced blood pressure responses to sympathomimetic agents such as pseudoephedrine and requires monitoring in people with uncontrolled hypertension. Caffeine is not a sympathomimetic amine and is not mentioned.
What was searched and not found
Europe PMC searches for linezolid with caffeine, guarana or green tea returned only analytical and environmental papers, and a search for caffeine with MAO inhibitors and blood pressure returned no original study. The European herbal monograph on guarana could not be retrieved. No exact-pair evidence was located.
What guarana delivers
A 500 mg guarana capsule supplied 130 mg caffeine in one controlled study, and measured caffeine in supplements often runs 4 to 35 percent above the declared amount. That is the dose to weigh against any personal sensitivity to stimulants during treatment.
Practical approach
If your blood pressure is controlled and you tolerate caffeine, the inspected evidence gives no specific reason to stop guarana for a linezolid course. If you have high blood pressure, palpitations or are also using decongestants, pause stimulant supplements and follow the label's monitoring advice. Report a severe headache, chest pain or a very high reading promptly.
Evidence and practical considerations
Side effects & toxicity
No evidence was found that linezolid changes the effect of guarana or caffeine; the label's pressor warning concerns sympathomimetic agents. Guarana's variable caffeine content is the only documented consideration.
- Exact scope
- Guarana seed extracts and powders; caffeine content varies by product. with Linezolid tablets, oral suspension and intravenous injection (ZYVOX and generics); the reversible, nonselective MAO inhibition is a property of the drug at all routes.
- Medication form and route
- oral medication; intravenous medication; oral supplement
What remains uncertain
- No exact-pair or caffeine plus MAO inhibitor study located; the EMA monograph was inaccessible; label silent on caffeine.
Factors that may matter: Caffeine dose and other stimulant sources; Existing high blood pressure; Concurrent decongestants.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 22, 2026
Population: People prescribed linezolid
The label's blood pressure interaction warning covers directly and indirectly acting sympathomimetic agents, vasopressors and dopaminergic agents; caffeine and guarana are not mentioned.
How this applies: Exact linezolid (RxCUI 190376) at every marketed route; the label names tyramine, pseudoephedrine, phenylpropanolamine and serotonergic agents, not the supplements assessed here.
Absence of caffeine from the label is not evidence of safety; it means no labelled interaction was established.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Twenty adult participants.
Neither guarana nor low-dose caffeine changed response time, heart rate variability or provided consistent mood benefit; the guarana dose supplied 130 mg caffeine.
How this applies: Documents the caffeine content of a typical guarana dose and the absence of a measurable acute autonomic effect; not an interaction study.
Cognitive and vagal endpoints, not blood pressure; no linezolid; abstract only.
Source 3: analytical product study
pubmed.ncbi.nlm.nih.gov · Source check Sep 22, 2026
Population: Not applicable (product analysis).
Caffeine content in most tested supplements was 4 to 35 percent higher than declared on the label.
How this applies: Shows that the caffeine dose from guarana-type supplements can exceed the label, which matters for anyone limiting stimulants.
Analytical study of products, not a clinical study; abstract only.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Prepared exact linezolid and Paullinia cupana article from inspected current labeling and original sources, with uncertainty stated. |
Article revision: 2a8241ddea168929
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.