NutriStack
ContraindicatedStrong evidence
What is happening. St. John's Wort is serotonergic and is inappropriate with irreversible MAOIs.
Mechanism. Additive serotonergic activity during MAO-A and MAO-B inhibition.
Recommendation. Do not use with phenelzine.
Supplement × Prescription·contraindicated·Strong evidence
Phenelzine + St. John's Wort
Contraindicated
Strong evidence
St. John's Wort is serotonergic and is inappropriate with irreversible MAOIs.
From the database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, and the recommendation.
Substances
Pair type
Contraindicated
Evidence
Strong
Source citations
1
Scope
Supplement × Prescription
Last verified
June 4, 2026
Stack Score
How it moves the number.
Effect on the composite score
If both Phenelzine and St. John's Wort are in the same stack, this pair applies −25 to your Stack Score (per scored contraindication row).
The full algorithm, the clamping rules, and four worked stacks are at /methodology/stack-score.
Sources
Sources, by evidence tier.
Every claim on this page is cited. PMIDs link straight to PubMed.
Reference material
1- 1U.S. National Library of Medicine. Phenelzine sulfate tablets US Prescribing Information. 2017.Needs sourceNo link
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