Interaction databaseSupplement × PrescriptionReviewed May 2026

5-HTP and MAOIs, contraindicated.

5-HTP increases serotonin synthesis while MAOIs reduce monoamine breakdown. Combining them can cause dangerous serotonergic excess and serotonin syndrome.

One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.

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Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.

At a glance

Substances
5-HTP and MAOIs
Pair type
Contraindicated
Evidence (highest tier)
Strong
Source citations
1 source
Stack Score effect
−25 to your Stack Score (per scored contraindication row).
Scope
Supplement × Prescription
Last verified
May 30, 2026

Contraindicated · Strong evidence

Contraindicated

What is happening. 5-HTP increases serotonin synthesis while MAOIs reduce monoamine breakdown. Combining them can cause dangerous serotonergic excess and serotonin syndrome.

Mechanism. 5-HTP bypasses tryptophan hydroxylase to increase serotonin production; MAOIs inhibit serotonin breakdown.

Recommendation. Do NOT combine 5-HTP with MAOIs. Use only if the prescriber managing the MAOI explicitly directs it and provides washout instructions.

Sources (1)
  1. Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med. 2005;352(11):1112-1120. PMID 15784664

Stack Score

How this pair moves the number.

Effect on the composite score

If both 5-HTP and MAOIs 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 documented at /methodology/stack-score.

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