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Isocarboxazid and L-Tryptophan, contraindicated.
L-Tryptophan feeds serotonin synthesis while Isocarboxazid reduces serotonin breakdown, increasing risk of 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.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Isocarboxazid and L-Tryptophan
- 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. L-Tryptophan feeds serotonin synthesis while Isocarboxazid reduces serotonin breakdown, increasing risk of serotonin syndrome.
Mechanism. Tryptophan is converted to 5-HTP and then serotonin; MAOIs reduce monoamine breakdown.
Recommendation. Do NOT combine L-tryptophan with Isocarboxazid unless specifically directed and monitored by the prescriber managing Isocarboxazid.
Sources (1)
Stack Score
How this pair moves the number.
Effect on the composite score
If both Isocarboxazid and L-Tryptophan 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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