Know2eat

5-HTP (5-hydroxytryptophan)

Griffonia simplicifolia

Amino Acids & Proteins

What 5-htp (5-hydroxytryptophan) may help with

Ranked by how strong the human evidence is — best supported first.

Best supportedMoodNot enough evidence· 3 sources

Then, in order

About 5-HTP (5-hydroxytryptophan)

The immediate metabolic precursor to serotonin, extracted commercially from the seeds of the West African shrub Griffonia simplicifolia. Unlike tryptophan it crosses the blood-brain barrier without competing for a transporter.

5-HTP sits one enzymatic step from serotonin, which makes it both the most pharmacologically direct supplement in this file and the most genuinely risky. A Cochrane review of 5-HTP and tryptophan for depression found 108 trials of which only two were of adequate quality, and concluded the evidence was insufficient to establish efficacy while flagging the safety concerns. Those concerns are real: serotonin syndrome is a recognised risk when 5-HTP is combined with serotonergic drugs, and cases resembling eosinophilia-myalgia syndrome have been reported in association with a contaminant found in some 5-HTP products.

Sold as
Capsule, Tablet, Enteric-coated capsule, Timed-release
Standardised to
mg 5-HTP; usually 95%+ from Griffonia seed extract — a product without this marker may not resemble what was studied.
Also known as
5-HTP, Oxitriptan, Griffonia seed extract

Regulation: Sold as a dietary supplement in the US with no pre-market efficacy or safety review. It is a prescription medicine (oxitriptan) in some countries. Regulators in several jurisdictions have restricted or advised against its sale, and it is not permitted as a food supplement ingredient in some European markets.

What the research used

The amounts, forms and durations published trials of 5-HTP (5-hydroxytryptophan) actually administered.

These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.

  • Studied for Depression trials

    150–300 mg

    Not enough

    Divided doses daily · 2–6 weeks

    Recorded because trials used these amounts, not because efficacy was established. Systematic review found the great majority of trials too poor in quality to interpret.

  • Studied for Sleep studies

    100–300 mg

    Not enough

    Single evening dose

    Small studies report changes in sleep architecture. The evidence is thin and dosing is not well established for this use.

This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.

When it was taken

Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.

None of the timings below were directly compared in a trial. They reflect how the research happened to dose, or what the pharmacology implies — which is not the same as a timing being better.

  • Evening

    Not enough

    Taken in the evening in sleep studies, on the basis that serotonin is the precursor to melatonin and that daytime dosing is more likely to cause nausea. The pharmacology is established; the timing has not been compared for efficacy in a trial.

    Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.

The evidence in depth

Best supported: Not enough

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.

Mood

Mental Wellbeing
Not enough evidence

A Cochrane review of 5-HTP and tryptophan for depression identified 108 trials and found only two of sufficient quality to include, concluding that evidence of effectiveness was insufficient and that safety concerns were unresolved. There is not enough dependable evidence to support the use this is mostly sold for.

What may be going on: It is decarboxylated to serotonin, and unlike tryptophan it bypasses the rate-limiting hydroxylation step and does not compete for blood-brain barrier transport.

Not enough evidence. Not enough human research to say anything useful yet.

View the 3 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Satiety and appetite

Weight Management
Not enough evidence

A few small trials from the 1990s reported reduced energy intake with 5-HTP. They are old, small and have not been replicated to modern standards.

Not enough evidence. Not enough human research to say anything useful yet.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Sleep quality

Sleep
Not enough evidence

Small studies report changes in sleep architecture with 5-HTP, often in combination products. There is not enough good-quality human evidence to support a sleep claim.

Not enough evidence. Not enough human research to say anything useful yet.

View the 4 sources

Deep research mode adds each paper’s own conclusion and stated limitations.

Things to know

Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.

  • Interaction

    Serotonin syndrome

    Interacts withSSRIs, SNRIs, MAO inhibitors, tricyclic antidepressants, triptans, tramadol, lithium, St John’s wort

    Combining 5-HTP with SSRIs, SNRIs, MAO inhibitors, tricyclic antidepressants, triptans, tramadol, lithium, St John’s wort or other serotonergic agents can precipitate serotonin syndrome — agitation, hyperthermia, tremor, rapid heart rate, in severe cases fatal. This is the single most important fact about 5-HTP, and it is a real clinical event rather than a theoretical interaction.

  • Worth knowing

    Contaminant associated with eosinophilia-myalgia-like illness

    A contaminant designated "peak X" has been detected in some 5-HTP products, and cases resembling eosinophilia-myalgia syndrome have been reported in association with its use, echoing the 1989 L-tryptophan outbreak. The link is not definitively established, but the parallel is close enough that regulators have taken it seriously.

  • Worth knowing

    Cardiac valve concern with peripheral serotonin

    Serotonin acting on 5-HT2B receptors is the mechanism behind valvular heart disease seen with fenfluramine and some ergot drugs. 5-HTP taken without a peripheral decarboxylase inhibitor raises serotonin outside the brain as well as inside it, which is a theoretical concern with long-term use that has not been studied.

  • Avoid

    Pregnancy, breastfeeding and children

    Safety has not been established in pregnancy, breastfeeding or childhood, and the serotonergic pharmacology is a reason for caution rather than assumption.

  • Too much

    Nausea is the dose-limiting effect

    Nausea, vomiting and diarrhoea are common, caused by serotonin acting on the gut, and are the usual reason people cannot tolerate higher doses.

Evidence ratings on this page: 3 not enough evidence.

Supplements are sold in the US without pre-market review of efficacy or safety. Nothing on this page is a recommendation to take 5-HTP (5-hydroxytryptophan), or a dose to follow.