50–300 mg/day, starting low. For sleep, at night; usually combined with dinner.
Increases the feeling of fullness and may reduce intake.
View the study (clinical trial) →It may help, but the evidence is old and of low quality; good trials are lacking.
View the study (Cochrane review) →May help with sleep, sometimes combined with GABA.
View the study (clinical trial) →Small studies in panic showed a reduction in attacks with 5-HTP + carbidopa; old evidence of limited quality. Extrapolate with caution.
View the study (clinical trial) →Modest anxiolytic effect via the serotonergic route. Do NOT combine with SSRIs/MAOIs/triptans (risk of serotonin syndrome).
View the study (clinical trial) →⏱ 3 min read
5-Hydroxytryptophan is the direct precursor of serotonin, which means it is only one enzymatic step away from the neurotransmitter that regulates mood, sleep, appetite, and many other critical physiological processes; it is commercially extracted from the seeds of the African plant Griffonia simplicifolia, and its theoretical usefulness rests on the fact that dietary tryptophan (its precursor) competes with other amino acids to enter the brain, whereas 5-HTP crosses the blood-brain barrier without that competition.
Unlike pharmacological serotonergic antidepressants (SSRIs), which act by modulating the reuptake of serotonin that has already been produced, 5-HTP increases the availability of the substrate for synthesizing more serotonin, which in theory could compensate for deficits in people with deficient production of the neurotransmitter; in practice, the clinical response is heterogeneous and depends on factors that basic science has not yet characterized well.
The older clinical trials of 5-HTP in depression showed efficacy comparable to tricyclic antidepressants in some small studies, but the methodological quality was limited and modern meta-analyses consider the evidence globally insufficient to recommend it as a primary treatment for clinical depression; it does seem to be useful as an adjunct in mild depression, especially when combined with vitamin B6 and carbidopa supplementation to optimize its conversion to serotonin in the brain.
The doses used in these studies range from 50 to 300 milligrams per day, divided into two or three doses; antidepressant effects usually appear in 2 to 4 weeks, similar to the response time of pharmacological antidepressants, and the clinical response varies greatly between people because individual differences in tryptophan metabolism and in the polymorphism of serotonin receptors appear to have a significant influence.
In sleep-onset insomnia, low-dose 5-HTP (100 to 200 milligrams before bedtime) may make it easier to fall asleep and improve the subjective quality of rest in people with mild difficulties, especially those whose problem seems related to a serotonergic deficit (mental rumination at bedtime, low mood associated with insomnia); it is not as well studied as melatonin or valerian, but it may be useful when those do not work.
In migraine, several small studies have shown modest reductions in frequency and intensity with 400 to 600 milligrams per day over months, a classic indication for 5-HTP that has been overshadowed by more effective pharmacological options such as triptans for the acute episode and riboflavin, magnesium, or coenzyme Q10 for prevention.
5-HTP has shown modest effects on appetite in people with overweight: doses of 600 to 900 milligrams per day reduce the feeling of hunger and spontaneous caloric intake in controlled trials, especially the preference for refined carbohydrates, a typical pattern in people with low mood and late-afternoon cravings for sweets and white flour products that brain serotonin appears to modulate directly.
The most important warning about 5-HTP is the interaction with any drug that increases brain serotonin: SSRI antidepressants, MAOIs, tramadol, migraine triptans, ondansetron, and lithium, among others, because the combination can precipitate serotonin syndrome, a serious medical emergency with confusion, agitation, sweating, hyperthermia, and, in severe cases, seizures; it should never be combined with serotonergic medication without medical consultation.
Nausea is common at the start, especially with high doses; it eases by taking 5-HTP with meals and starting with low doses (50 mg) that are increased gradually; pregnancy, breastfeeding, and severe psychiatric disorders are situations in which it should not be used without clinical supervision, and product quality matters because contamination with the "Peak X" peptide in the 1990s caused an outbreak of eosinophilia-myalgia syndrome that still shapes regulation in some countries.
Information, not medical advice. Scientific evidence reflects the quality of the studies.