The short answer
Check the caffeine content of green tea extract with your pharmacist before taking it with isocarboxazid. Marplan warns against excessive caffeine in any form. A caffeine-free extract is a different exposure, but is not automatically proven safe with this medication.
What this answer covers
Oral Camellia Sinensis Leaf Extract; caffeine amount and extraction method must be known. This assessment does not cover topical tea products.
- Supplement or preparation
- Camellia Sinensis Leaf Extract
- Medication ingredient
- isocarboxazid
Why caffeine content matters
Marplan warns against excessive caffeine in any form. Green tea extract can contribute to total intake, along with coffee, tea, energy products and other supplements. The medication label does not provide a universal safe caffeine limit.
Caffeinated and decaffeinated extracts differ
A trial of a defined decaffeinated tea capsule in healthy adults found lower blood pressure. That result does not establish safety with isocarboxazid, but it cautions against assuming every tea extract raises blood pressure.
What to check with your pharmacist
Bring the exact product and serving size. Ask about caffeine content and other stimulant ingredients before starting it. A few hours of separation has not been established as protection against excessive caffeine exposure.
When to seek help
Get urgent medical care for a sudden severe headache, chest pain or a pounding heartbeat, particularly with sweating or neck stiffness. These may be warning signs of a serious blood-pressure reaction during Marplan treatment.
Evidence and practical considerations
Timing & monitoring
Check the caffeine content of green tea extract with your pharmacist before taking it with isocarboxazid. Marplan warns against excessive caffeine in any form. A caffeine-free extract is a different exposure, but is not automatically proven safe with this medication.
- Exact scope
- Oral Camellia Sinensis Leaf Extract; caffeine amount and extraction method must be known. This assessment does not cover topical tea products. with isocarboxazid, RxCUI 6011 IN; oral MARPLAN tablets.
- Medication form and route
- Oral isocarboxazid; oral supplement
What remains uncertain
- No direct isocarboxazid and tea-extract trial was identified. The relevant concern depends on caffeine content and total intake. The evidence does not establish a need for tea extract or a protective spacing interval.
Factors that may matter: Exact product composition and dose; Other medicines and supplements.
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 isocarboxazid tablets.
Phenylalanine is named among substances that may precipitate hypertension and headache. Sympathomimetics, some CNS depressants and excessive caffeine are contraindicated. The label describes high-tyramine hypertensive crises and warns about drowsiness, hypotension and impaired driving.
How this applies: Exact isocarboxazid authority. Botanical applicability must be assessed from the relevant constituent or sedating effect rather than a botanical name alone.
The label does not quantify these botanical pair risks or give a universally safe supplement dose.
Source 2: Federal botanical safety information
nccih.nih.gov · Source check Sep 10, 2026
Population: Consumers of green tea beverages, oral extracts and a distinct topical prescription preparation.
Tea contains caffeine; oral extracts differ from beverages and can have adverse effects including increased blood pressure.
How this applies: Not an exact MAOI interaction study. The botanical name alone cannot establish caffeine content, extract equivalence or suitability of a specific product.
Not an exact MAOI interaction study. The botanical name alone cannot establish caffeine content, extract equivalence or suitability of a specific product.
Source 3: Original randomized human study
ebi.ac.uk · Source check Sep 10, 2026
Population: 111 healthy adults aged 21 to 70; no isocarboxazid coadministration.
Blood pressure decreased after three weeks; systolic reduction persisted at three months. Adverse events were mild, few and similar to placebo.
How this applies: Abstract only. This particular decaffeinated product cannot establish safety with isocarboxazid or equivalence to caffeinated extracts.
Abstract only. This particular decaffeinated product cannot establish safety with isocarboxazid or equivalence to caffeinated extracts.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources checked and article drafted. | |
| Clarified the distinction between the original dataset statement and the narrower source-supported precaution, and edited evidence limitations for readers. | |
| Research summary published |
Article revision: 937baa06d9898d86
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.