Medication · maoi

Supplements and Phenelzine.

Every documented pair, every citation. Below: 2 documented pairs grouped by mechanism.

Phenelzine, sold under the brand name Nardil, is a monoamine oxidase inhibitor (MAOI): it irreversibly inhibits MAO-A and MAO-B, with strict dietary and drug interaction rules.

Below are the 2 documented pairs we have explicitly assessed against Phenelzine in the Distil database: 2 red. The pairs cluster around 1 mechanism: Additive serotonergic activity. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.

Documented interactions

Additive serotonergic activity

Red 5-HTP

5-HTP raises serotonin levels. Combined with an MAOI like phenelzine, which blocks serotonin breakdown, this can produce severe serotonin syndrome. Do not combine.

BNF: Phenelzine

Red St John's Wort

St John's Wort with an MAOI like phenelzine can cause hypertensive crisis and serotonin syndrome. This is a strict do-not-combine.

BNF: Phenelzine

What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

Loading database stats…

For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

Anything we should know? (optional)

Pick any that apply. We adjust the findings where context changes the answer.

Your supplements

Type the supplement name. Click each match to add it.

Your medications

Brand or generic name works. Click each match to add it.

How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

Read the full methodology

Something missing?

If a supplement or medication you take isn't in our autocomplete, tell us and we'll add it in the next quarterly update.

Thanks. Logged for the next quarterly update.

Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a comprehensive personalised stack reasoned against this same database, the Distil report is the next step up.