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5-Hydroxytryptophan
Direct serotonin precursor that may support mood, sleep, and appetite control, but requires caution with certain medications.
What the evidence says
5-HTP appears to help in 6 of 7 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 2002–2026 with a typical study size of 41 participants.
Based on 28 studies · 1 meta-analysis · 21 RCTs · 6,298 total participants
Confidence
HighWhat the studies found
By outcome
See full supplement plans that include 5-HTP.
5-HTP has an evidence score of 8.5/10 — very strong evidence based on 28 indexed studies, including 3 meta-analyses. Direct serotonin precursor that may support mood, sleep, and appetite control, but requires caution with certain medications.
The commonly studied dose of 5-HTP is 50-100mg for sleep; 150-300mg for mood. Research points to an estimated optimal dose around 200mg, with a minimum effective dose near 100mg. Individual response varies — start low and adjust.
The best time to take 5-HTP is before bed. It can be taken on an empty stomach. 5-HTP is a direct serotonin precursor that crosses the blood-brain barrier.
Last reviewed May 2026 · evidence from 38 studies · how we score
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
5-HTP is the immediate precursor to serotonin, the neurotransmitter associated with mood, sleep, and appetite. Derived from the seeds of Griffonia simplicifolia, it crosses the blood-brain barrier and converts directly to serotonin. Can be effective for mood support and sleep, but interactions with serotonergic medications are a serious concern.
Directly converts to serotonin in the brain
Serotonin converts to melatonin for sleep
How 5-HTP works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Tap node to isolate • Pinch to zoom • Tap edge for research
50-100mg for sleep; 150-300mg for mood
Take with food
| Form | Type |
|---|---|
| 💊Capsules | Recommended |
| 💊Tablets | Alternative |
| 💊Extended-release | Alternative |
Start with lower doses and increase gradually. Some prefer taking with B6 for conversion support (though not always necessary).
Minimum: 2 weeks
Optimal: 4 weeks
Cycling: Not intended for long-term continuous use. Use for specific periods (4-8 weeks), then take breaks. Long-term safety data is limited.
Note: Taking with a carbohydrate may improve brain uptake. For sleep, take in evening. For mood, divide doses throughout day.
Limited evidence from small RCTs (n=30, n=166). Effectiveness constrained by mixed study populations and preliminary findings. Higher doses associated with increased nausea risk.
May lift mood and reduce depressive symptoms
Improved sleep quality and onset
May reduce carbohydrate cravings
Common side effect, especially at higher doses
Avoid — may affect fetal development
Do NOT use without medical supervision
Not recommended
Risk of serotonin syndrome — potentially life-threatening
Risk of serotonin syndrome
Both increase serotonin; dangerous combination
Tip: Take with food; start with low dose; use ginger
Tip: Take in evening; reduce dose
Tip: Take with meals
Tip: Reduce dose
5-HTP is generally safe at recommended doses, with a few precautions worth noting. The most commonly reported side effects are nausea, drowsiness, GI upset. Use caution if any of these apply to you: Currently taking SSRIs, SNRIs, MAOIs, or other serotonergic drugs; Carcinoid syndrome; Scleroderma.
GABA
Mostly mechanism / observationalInhibitory neurotransmitter that calms neural activity — may work through the gut-brain axis for acute anxiety and sleep support.
Additive serotonergic effects
May increase 5-HTP effects and side effects
Serotonin syndrome risk
Severe serotonin syndrome
Risk of serotonin syndrome