NutriStack
L-Tryptophan and Paroxetine, contraindicated.
L-Tryptophan is the upstream precursor to serotonin. Combined with paroxetine's potent serotonin reuptake blockade, supplemental L-tryptophan can push synaptic serotonin to toxic levels and trigger serotonin syndrome (agitation, tremor, sweating, hyperthermia, clonus).
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.
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At a glance
- Substances
- L-Tryptophan and Paroxetine
- Pair type
- Contraindicated
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- 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 is the upstream precursor to serotonin. Combined with paroxetine's potent serotonin reuptake blockade, supplemental L-tryptophan can push synaptic serotonin to toxic levels and trigger serotonin syndrome (agitation, tremor, sweating, hyperthermia, clonus).
Mechanism. L-Tryptophan is converted to 5-HTP then serotonin. Paroxetine blocks the serotonin transporter; both inputs raise synaptic serotonin to potentially toxic concentrations.
Recommendation. Do not take L-tryptophan supplements with paroxetine. Dietary protein-bound tryptophan is fine; concentrated supplemental doses are the issue.
Stack Score
How this pair moves the number.
Effect on the composite score
If both L-Tryptophan and Paroxetine 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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