Skip to content
    Back to Database
    Amino AcidsNatural

    5-HTP

    Also known as: 5-hydroxytryptophan, 5-HTP, oxitriptan

    A 12-week randomized trial in older adults found 100 mg/day 5-HTP improved some subjective sleep components and increased serum serotonin, with greater benefit in participants who were poor sleepers. Cochrane-style systematic reviews of trials for depression (combining tryptophan and 5-HTP trials) reported some benefit versus placebo but concluded the evidence was limited and of insufficient quality to be conclusive.

    Last reviewed: 2026-10-14 · 3 indexed studies

    Evidence Score
    50/100
    Support for sleep qualitySupport for low mood / mild depressionGeneral mood and well‑being
    Data Completeness4/4 · 100%
    Evidence ScoreDosageSafetyLinked Studies

    Set your location for accurate regulatory status

    Saved on this device — no sign-in needed.

    Sign in to add to stack

    Overview

    5-Hydroxytryptophan (5-HTP) is the immediate metabolic precursor to serotonin and a commonly used oral supplement. Human trials and systematic reviews have examined its effects on sleep and depressive symptoms, though the clinical evidence base contains few high‑quality, large trials.

    Mechanism & Function

    Mechanism of Action

    Acts as a biochemical precursor in the tryptophan → 5-HTP → serotonin pathway; increased peripheral 5-HTP can raise serum serotonin and, via downstream pathways, may increase melatonin production involved in sleep regulation (pathway referenced in the provided abstracts).

    Physiological Role

    Precursor to serotonin and, indirectly, melatonin; implicated in regulation of mood and sleep through serotonergic pathways.

    Primary Pathways

    Tryptophan → 5-HTP → SerotoninSerotonin → Melatonin (indirect, sleep regulation)

    Performance / Health Relevance

    May modestly improve subjective sleep quality in some populations (older adults with poor sleep). Evidence for effects on mood/depression is limited and based on small, older trials.

    Evidence Review

    Overall50/100
    Human Clinical40/100
    Meta-Analysis55/100
    Mechanistic70/100
    Real-World35/100
    Safety60/100

    Practical Use & Dosage

    Minimum Effective Dose
    100 mg/day (shown to improve some sleep outcomes in a 12‑week RCT of older adults)
    Optimal Range
    Not established from the provided abstracts
    Upper / Caution Level
    Not established from the provided abstracts
    Timing
    Daily oral dosing (timing relative to bedtime not specified in provided abstracts)
    Best Format
    Oral capsule/tablet
    Bioavailability
    5-HTP is an intermediate in serotonin synthesis; oral 5-HTP can increase serum serotonin (reported in the provided RCT).
    Absorption Considerations
    Not detailed in the provided abstracts

    Safety & Interactions

    Side Effects

    • •Gastrointestinal upset (nausea/vomiting reported in some trials in the literature; not specified in the provided abstracts)
    • •Potential for increased serotonergic effects

    Contraindications

    • Concomitant use with serotonergic antidepressants (SSRIs, SNRIs) or MAO inhibitors due to risk of serotonin excess

    Drug Interactions

    • •SSRIs, SNRIs, MAO inhibitors, and other serotonergic agents (risk of serotonin syndrome)

    Who Should Avoid

    • •People taking prescription antidepressants or other serotonergic drugs
    • •Pregnant or breastfeeding women (safety not established in provided abstracts)

    Monitoring

    Monitor for symptoms of serotonin excess if combined with other serotonergic agents; seek medical advice before combining with antidepressants.

    Frequently Asked Questions

    Auto-generated from indexed evidence — dosage, safety, interactions, and more.

    When is 5-HTP typically used or indicated?

    5-HTP is most commonly used for: Support for sleep quality, Support for low mood / mild depression, General mood and well‑being. Precursor to serotonin and, indirectly, melatonin; implicated in regulation of mood and sleep through serotonergic pathways.

    How does 5-HTP work?

    Acts as a biochemical precursor in the tryptophan → 5-HTP → serotonin pathway; increased peripheral 5-HTP can raise serum serotonin and, via downstream pathways, may increase melatonin production involved in sleep regulation (pathway referenced in the provided abstracts).

    What is the recommended dose of 5-HTP?

    The optimal range is Not established from the provided abstracts. with a minimum effective dose of 100 mg/day (shown to improve some sleep outcomes in a 12‑week RCT of older adults). Best taken: Daily oral dosing (timing relative to bedtime not specified in provided abstracts). Upper / caution level: Not established from the provided abstracts.

    What are the side effects of 5-HTP?

    Reported side effects include: Gastrointestinal upset (nausea/vomiting reported in some trials in the literature; not specified in the provided abstracts); and Potential for increased serotonergic effects. Monitoring: Monitor for symptoms of serotonin excess if combined with other serotonergic agents; seek medical advice before combining with antidepressants.

    Does 5-HTP interact with medications?

    Known or theoretical interactions: SSRIs, SNRIs, MAO inhibitors, and other serotonergic agents (risk of serotonin syndrome). Always check with a clinician before combining with prescription medication.

    Who should avoid 5-HTP?

    5-HTP is generally not recommended for: People taking prescription antidepressants or other serotonergic drugs; Pregnant or breastfeeding women (safety not established in provided abstracts); and Concomitant use with serotonergic antidepressants (SSRIs, SNRIs) or MAO inhibitors due to risk of serotonin excess.

    How strong is the evidence for 5-HTP?

    Evidence level: Limited (overall score 50/100), based on 3 indexed studies on SuppIndex.

    Research & References (3)

    The impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: A randomized controlled trial.

    RCT2024
    PubMed

    12-week single‑blinded RCT in 30 older adults assessing 100 mg/day 5-HTP versus control, measuring subjective and objective sleep, serum serotonin, urine melatonin, and gut microbiota.

    Tryptophan and 5-hydroxytryptophan for depression.

    Systematic Review2001
    PubMed

    Systematic review combining trials of tryptophan and 5-HTP for unipolar depression; of many located trials only two trials (total n=64) met quality criteria for inclusion.

    Tryptophan and 5-hydroxytryptophan for depression.

    Systematic Review2002
    PubMed

    Independent systematic review with similar methods and conclusions to PMID 11687048, finding limited, low‑quality evidence suggesting benefit of tryptophan/5-HTP versus placebo for depression but insufficient to recommend widespread use.

    Related Ingredients

    Other top-rated ingredients in Amino Acids.

    L-Leucine

    82/100

    Essential BCAA that activates mTORC1 via Sestrin2 sensing, driving phosphorylation of S6K1 and 4E-BP1, initiating cap-dependent translation and muscle protein synthesis.

    Beta-Alanine

    78/100

    A rate-limiting precursor to carnosine (β-alanyl-L-histidine) synthesis, enhancing intramuscular pH buffering capacity during high-intensity anaerobic exercise.

    EAA Blend

    78/100

    Free-form blend of 9 EAAs (Leu, Ile, Val, Lys, Met, Phe, Thr, Trp, His) at evidence-based ratios; bypasses gastric digestion for rapid plasma aminoacidaemia.

    Research Overview

    Limited Evidence
    3Total Studies
    1Human Trials
    0Meta-Analyses
    2024Latest Study
    0Animal / In Vitro
    0Athlete Studies
    Primary data sourceClinical Patients
    Pooled evidence (meta-analysis / systematic review)Yes

    Cite this ingredient

    One-click citation export in APA, MLA, Chicago, BibTeX, or HTML. The URL below is stable and safe to link.

    Stable URL

    https://thesuppindex.com/ingredients/5-htp

    SuppIndex. (2026). 5-HTP: Evidence summary, dosage and clinical studies. Retrieved October 16, 2026, from https://thesuppindex.com/ingredients/5-htp

    Based on 3 indexed studies · Evidence level: Limited.

    Goal Ratings

    Sleep
    General Health

    Stack Compatibility

    Avoid stacking with prescription serotonergic medications. Other supplements that increase serotonin or melatonin should be used cautiously.

    Melatonin (use with caution; combined effects on sleep/melatonin not established in provided abstracts)Avoid combining with prescription antidepressants (SSRIs, SNRIs, MAOIs)