# 5-HTP (5-hydroxytryptophan)

Source: https://onco.cc/technologies/five-htp-supplements/  
OnCo record `five-htp-supplements` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

5-HTP is sold for sleep, mood and appetite. Trials are small and mixed and it did not help hot flushes. It matters for two groups: people on antidepressants, where it can add to serotonin and cause a dangerous reaction, and people with neuroendocrine tumours, because it distorts the urine test used to monitor them.

## Summary

5-HTP is the immediate precursor of serotonin, extracted mainly from the seeds of the African shrub Griffonia simplicifolia. Memorial Sloan Kettering's About Herbs entry describes most human research as small trials with mixed results: possible effects on anxiety and depression but not treatment-resistant depression, preliminary appetite effects, and no benefit for postmenopausal hot flushes, chronic tension headache or childhood migraine. Its oncology relevance is mainly safety. People taking SSRIs, MAO inhibitors, tricyclics, the antibiotic linezolid or other serotonergic drugs should avoid it without medical supervision; MSK lists case reports of serotonin syndrome with linezolid and mania with an MAO inhibitor, and advises against combining it with St John's wort or SAM-e. 5-HTP raises urinary 5-HIAA and serum chromogranin A, the markers used to diagnose and monitor carcinoid and other neuroendocrine tumours, and can lead to misreading of those tests. Older reports found contaminants in some products, one linked to eosinophilia-myalgia in a family.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-11-04
- Also known as: 5-HTP; L-5-hydroxytryptophan; Griffonia seed extract
- Tags: complementary; supportive-care; evidence:insufficient
- Principle: Converted directly to serotonin, bypassing the rate-limiting step of tryptophan hydroxylase, so it adds to any drug that raises serotonin and to the serotonin metabolites measured in neuroendocrine tumour tests.
- Strengths: Small trials for mood and appetite
- Limitations: Serotonin syndrome risk with antidepressants and linezolid; Falsely raises 5-HIAA and chromogranin A in neuroendocrine tumour monitoring; No benefit for hot flushes; contamination history

## Sources

- MSK About Herbs: 5-HTP (page last updated 2 June 2022): https://www.mskcc.org/cancer-care/integrative-medicine/herbs/5-htp-01

## Connected records

- technologies: [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/), [L-theanine](https://onco.cc/technologies/l-theanine-supplements/), [Psycho-oncology and distress screening](https://onco.cc/technologies/psycho-oncology/), [SAM-e (S-adenosylmethionine)](https://onco.cc/technologies/sam-e-supplements/), [St John's wort: an interaction to avoid](https://onco.cc/technologies/st-johns-wort-interaction/)
- cancers: [Neuroendocrine tumours](https://onco.cc/cancers/neuroendocrine/)
- fronts: [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- terms: [Chromogranin A](https://onco.cc/terms/chromogranin-a/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)

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