5-HTP

What it is

5-HTP (5-hydroxytryptophan) is an intermediate your body makes from the amino acid tryptophan on the way to serotonin. Supplements are usually extracted from the seeds of the African plant Griffonia simplicifolia.

It is taken in the hope of lifting mood, easing sleep or reducing appetite. Unlike tryptophan, it skips a step in the pathway, so it raises serotonin more directly.

That directness is also the main worry. Anything that raises serotonin can combine with other serotonin-raising drugs to cause serotonin syndrome, which can be serious.

How it works

After you swallow it, 5-HTP is converted to serotonin in the body and brain. Some conversion also happens in the gut and elsewhere, so effects are not limited to the brain. Serotonin is involved in mood, sleep and appetite, but taking a precursor does not guarantee a predictable effect.

What the evidence says

• Limited Mood and depression
  Small, older trials suggest some benefit but quality is low; it should not replace prescribed treatment.
• Weak Sleep
  Little good evidence that it helps in healthy people.
• Limited Appetite and weight
  A few small trials show reduced calorie intake, but nausea was a frequent problem.
• Weak Fibromyalgia and migraine
  Small and inconsistent studies; not established.

Evidence ratings are our plain-English summary of how much good human research exists, not a promise of results. How we rate evidence.

Dosage and timing

• Common ranges are 50-100 mg once to three times daily. Starting at the low end reduces nausea.
• Taking it with food may ease stomach upset.
• Do not combine with antidepressants or other serotonin-raising drugs unless a clinician advises it.
• There is no official UK upper limit; check current guidance and keep to label doses. Long-term use is not well studied.

Forms and what to look for

• Griffonia seed extract standardised to 5-HTP is the usual source.
• Some capsules are enteric-coated to reduce stomach upset.
• Check the label for mg of actual 5-HTP, not just mg of seed extract.
• Avoid products that hide the dose in blends.

What to expect, and when

• Nausea and stomach upset can appear within days, especially at higher doses.
• If it has any effect on mood, it would take weeks, and benefits are uncertain.
• Sleep effects, if any, are usually noticed in the first few nights.

Side effects

• Nausea, vomiting, diarrhoea and stomach cramps.
• Drowsiness or vivid dreams.
• Headache and dizziness.
• Too much serotonin: agitation, sweating, tremor, fast heart rate, fever; seek urgent medical help.

Interactions

• SSRIs, SNRIs, MAOIs, tricyclics and other antidepressants: risk of serotonin syndrome. Do not combine without medical supervision.
• Triptans (migraine), tramadol, pethidine, St John's wort and MDMA: also raise serotonin and add to the risk.
• Carbidopa (Parkinson's medicines): can cause skin changes or other problems when combined.
• Sedatives and alcohol: can add to drowsiness.

Who should avoid it

• Anyone taking antidepressants or other serotonergic drugs.
• Pregnancy and breastfeeding.
• People with heart disease or taking medicines for it, without advice.
• Anyone with a history of serotonin syndrome.
• Stop and tell your doctor before surgery or anaesthesia.

Risks and safety

• Serotonin syndrome is the main risk and can be life-threatening.
• A past contamination scare with tryptophan products (eosinophilia-myalgia syndrome) led to concern about impurities in 5-HTP. Cases have been reported, so buy from reputable sources.
• Long-term safety is uncertain.
• Not on the WADA prohibited list.

Buying well: quality and testing

• Prefer brands with batch testing and independent verification (NSF, USP, Labdoor).
• Check the label states mg of 5-HTP per capsule.
• Avoid unknown sellers or imported products with no testing.
• Be wary of "mood support" blends combining several serotonin-affecting ingredients.

Bottom line

5-HTP is not a gentle supplement to try on top of antidepressants. For people not on serotonergic medicines it may be tolerable, but the evidence is thin and side effects are common. If low mood or poor sleep is a persistent problem, it is worth talking to a GP or pharmacist rather than self-treating.