5-HTP

5-Hydroxytryptophan · Oxitriptan · Griffonia simplicifolia

Snapshot

Indications	Contraindications
Depressive symptoms¹ Depressive symptoms in Parkinson's² REM sleep in Parkinson's³ Fibromyalgia⁴ Anxiety⁴ Appetite and satiety⁴	Scleroderma⁵ Linezolid use⁴

5-Hydroxytryptophan (5-HTP) is the intermediate between tryptophan and serotonin, sourced commercially from Griffonia simplicifolia seeds⁴. It crosses the blood-brain barrier and raises central serotonin synthesis⁴. That effect drives its use for depressive symptoms. It is also used for anxiety and fibromyalgia, where findings are initial⁴, and for appetite control. Sleep is a further use, though trials are lacking⁴.

A 2020 meta-analysis reported high remission rates in depression, but the included studies were weak and few had placebo groups¹. A Cochrane review found it better than placebo, with evidence too poor to be conclusive⁶. Randomized trials in fatigue from inflammatory bowel disease and in adults with attention deficit hyperactivity disorder traits found no benefit over placebo. A 2026 narrative review of tryptophan-pathway modulators in depression, including 5-HTP, found long-term efficacy and standardized protocols still undefined⁷. Over 1,700 products in the NIH label database list 5-HTP, mostly capsules; see Form comparison.

The caution behind the pills is serotonin syndrome, reported with linezolid⁴. Health Canada labels ask for a practitioner's advice before use with carbidopa or serotonergic medications⁵.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

56 sources, 39 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources