NutriStack
5-HTP and Venlafaxine, contraindicated.
Venlafaxine is an SNRI that blocks serotonin reuptake, particularly at lower doses where its effect is predominantly serotonergic. Adding 5-HTP increases serotonin synthesis while venlafaxine prevents its clearance, creating significant serotonin syndrome risk.
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At a glance
- Substances
- 5-HTP and Venlafaxine
- Pair type
- Contraindicated
- Evidence (highest tier)
- Moderate
- Source citations
- 3 sources
- Stack Score effect
- −25 to your Stack Score (per scored contraindication row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Contraindicated · Moderate evidence
Contraindicated
What is happening. Venlafaxine is an SNRI that blocks serotonin reuptake, particularly at lower doses where its effect is predominantly serotonergic. Adding 5-HTP increases serotonin synthesis while venlafaxine prevents its clearance, creating significant serotonin syndrome risk.
Mechanism. Venlafaxine blocks SERT (predominantly at doses <150mg) and NET (at higher doses). 5-HTP increases serotonin synthesis by providing direct substrate for AADC. The combination of increased serotonin production and blocked reuptake can cause dangerous serotonin accumulation.
Recommendation. Do not combine 5-HTP with venlafaxine. The serotonin syndrome risk is significant. Discontinue 5-HTP before starting venlafaxine therapy.
Sources (3)
- Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med. 2005;352(11):1112-1120. PMID 15784664
- Truyens M, Lobatón T, Ferrante M et al.. Effect of 5-Hydroxytryptophan on Fatigue in Quiescent Inflammatory Bowel Disease: A Randomized Controlled Trial. Gastroenterology. 2022. PMID 35940251
- Sutanto CN, Xia X, Heng CW et al.. The impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: A randomized controlled trial. Clinical Nutrition. 2024. PMID 38309227
Stack Score
How this pair moves the number.
Effect on the composite score
If both 5-HTP and Venlafaxine 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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