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5-HTP Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Safe with Caution

Potential Side Effects

  • Nausea — most common side effect, often dose-dependent
  • GI upset (diarrhea, abdominal discomfort)
  • Drowsiness, especially at higher doses
  • Risk of serotonin syndrome when combined with serotonergic medications
  • Eosinophilia reported rarely; may be contaminant-related

Drug & Supplement Interactions

  • SSRIs, SNRIs, and MAOIs — serious risk of serotonin syndrome; contraindicated without medical supervision
  • Tramadol and other serotonergic pain medications — additive serotonin effects
  • Carbidopa — dramatically increases 5-HTP bioavailability; use only under medical guidance
  • L-Tryptophan — avoid combining; both raise serotonin levels

Maximum Dose

Do not exceed: 900 mg/day has been used in studies; doses above 300 mg increase risk of serotonin-related side effects

Full 5-HTP Guide

References

  1. RCTCangiano C, Ceci F, Cascino A, et al. (1992). Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan. American Journal of Clinical Nutrition. DOI PubMed
  2. RCTCaruso I, Sarzi Puttini P, Cazzola M, Azzolini V. (1990). Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. Journal of International Medical Research. DOI PubMed
  3. RCTLi S, Sutanto CN, Xia X, Kim JE (2025). The Impact of 5-Hydroxytryptophan Supplementation on Cognitive Function and Mood in Singapore Older Adults: A Randomized Controlled Trial.. Nutrients. DOI PubMed
  4. RCTSutanto CN, Xia X, Heng CW, Tan YS, et al. (2024). The impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: A randomized controlled trial.. Clinical nutrition (Edinburgh, Scotland). DOI PubMed
  5. Evans C, Mekhail V, Curtis J, Czartoryski P, et al. (2023). The Effects of 5-HTP on Body Composition: An 8-Week Preliminary RCT.. Journal of dietary supplements. DOI PubMed
  6. Zamoscik V, Schmidt SNL, Bravo R, Ugartemendia L, et al. (2021). Tryptophan-enriched diet or 5-hydroxytryptophan supplementation given in a randomized controlled trial impacts social cognition on a neural and behavioral level.. Scientific reports. DOI PubMed
  7. van der Burg KP, Cribb L, Firth J, Karmacoska D, et al. (2020). EPA and DHA as markers of nutraceutical treatment response in major depressive disorder.. European journal of nutrition. DOI PubMed
Show 2 more references
  1. Sarris J, Byrne GJ, Stough C, Bousman C, et al. (2019). Nutraceuticals for major depressive disorder- more is not merrier: An 8-week double-blind, randomised, controlled trial.. Journal of affective disorders. DOI PubMed
  2. Sauer H, Mack I, Kohler S, Siegle S, et al. (2014). The effects of 5-hydroxytryptophan in combination with different Fatty acids on gastrointestinal functions: a pilot experiment.. Gastroenterology research and practice. DOI PubMed