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Also known as 5-Hydroxytryptophan, Griffonia simplicifolia
Direct metabolic precursor to serotonin, derived from Griffonia simplicifolia seeds, bypassing the rate-limiting step in serotonin synthesis; must not be combined with SSRIs, MAOIs, or other serotonergic drugs due to serotonin syndrome risk.
We link to relevant studies and leave interpretation to you and your healthcare professional.
Number of audited published findings for 5-HTP by condition. Drill into a pair page for the full breakdown.
Where people report using it and what trials suggest
Common claims the trials do not support
Serotonin precursor with old, small depression trials and a genuinely important interaction risk with antidepressants.
Safety notes: Serotonin syndrome risk with SSRIs/SNRIs/MAOIs/tramadol — the key contraindication. Possible eosinophilia-myalgia link in impure historical batches.
Evidence grades reflect study quality and consistency, not marketing claims.
Summaries of published trial results for this compound, grouped by condition. Numbers are reported exactly as the researchers published them — we never calculate or convert.
How to read this table
In short: benefit is what was observed; evidence is how much you should trust the observation. A “Benefit seen” tag on a weak study counts for far less than the same tag on a meta-analysis.
| Outcome measured | What trials found | Effect size | People studied | Duration | Type of evidence | Study |
|---|---|---|---|---|---|---|
| depression remission rate | Depression remission rate was 0.65 across 13 studies, though placebo comparisons were limited. (95% confidence interval [CI], 0.55-0.78)Benefit seen | 0.65 | 13 | — | Meta-analysis · 2020 | PMID 31504850 |
| Hedges' g for depression symptoms | Depression scores showed a large effect size of 1.11 in 7 studies, with limited placebo controls. (95%CI, 0.53-1.69)Benefit seen | 1.11 | 7 | — | Meta-analysis · 2020 | PMID 31504850 |
| Depression symptom improvement (unipolar depression) |
Associated conditions and community-reported outcomes, wrapped together on one page. Aggregates appear only once enough reports arrive.
How this compound is sold in the UK, and where our readers typically find it.
Retailer search links — we may earn commission on purchases at no cost to you. Commission never affects our evidence ratings.
| 5-HTP and L-tryptophan were better than placebo at alleviating depression (Peto OR 4.1, 95% CI 1.3-13.2). (95% CI = 1.3-13.2)Benefit seen |
| 4.1 Peto OR |
| 64 |
| — |
| Meta-analysis · 2002 |
| PMID 12169147 |
| Depression symptom improvement (unipolar depression/dysthymia) | 5-HTP and tryptophan appeared better than placebo for depression (Peto OR 4.10, 95% CI 1.28-13.15), though evidence was limited. (95% confidence interval 1.28-13.15)Benefit seen | 4.10 Peto Odds Ratio | 64 | — | Systematic review · 2002 | PMID 11869656 |
| Depression symptom improvement (unipolar depression/dysthymia) | 5-HTP and tryptophan appeared better than placebo for depression (Peto OR 4.10, 95% CI 1.28-13.15), though evidence was limited. (95% confidence interval 1.28-13.15)Benefit seen | 4.10 Peto Odds Ratio | 64 | — | Systematic review · 2001 | PMID 11687048 |
| Apathy symptoms (AS) | No effect on apathy symptoms was seen with 5-HTP vs placebo in 25 people over 4 weeks.No clear benefit | no number reported | 25 | 4 weeks | RCT · 2020 | PMID 32067288 |
| Depressive symptoms (HDRS) | Depression scores improved significantly with 5-HTP vs placebo in 25 people over 4 weeks.Benefit seen | no number reported | 25 | 4 weeks | RCT · 2020 | PMID 32067288 |