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5-HTP

Amino acid · 5-hydroxytryptophan

5-HTP is the direct precursor of serotonin and is obtained from the seeds of the African plant Griffonia simplicifolia. That it actually becomes serotonin in the body has been measured in humans. Whether noticeably better mood or better sleep follows from that is considerably less clear.

In short

5-HTP is an intermediate product of the body’s own serotonin synthesis. As a preparation it measurably raises the serotonin level in the blood, as several randomized studies show. For mood, sleep and appetite there are positive signals, but almost only from small or old studies; the largest modern placebo experiment, with 166 people, found no clinical difference despite rising serotonin levels. The most important catch is the combination with antidepressants and other serotonergic agents. In Germany, 5-HTP is not an approved medicine, so this page gives no dosage.

What it is

5-hydroxytryptophan is formed in the body from the amino acid tryptophan. The first step, the conversion of tryptophan to 5-HTP, is the slowest of the entire serotonin synthesis. Supplying 5-HTP directly bypasses exactly this bottleneck. From it the body forms serotonin and, in a further step, melatonin.

Commercially, 5-HTP is almost always extracted from Griffonia seeds, because chemical synthesis on a large scale is not economical. In the EU, dietary supplements may only contain the seeds and extracts with at most 30 percent 5-HTP. As a medicine under the name oxitriptan, 5-HTP was once on the market in Germany, but the product Levothym was withdrawn from the market in 1992.

How it is supposed to work

The idea is simple: more starting material, more serotonin, better mood, better sleep, less appetite. The first two links of this chain have been shown in humans. In a PET study with 8 healthy volunteers and 6 patients with depression, labeled 5-HTP crossed the blood-brain barrier, though to a lesser extent in the depressed patients. And in randomized studies, both 5-HTP and serotonin in the blood rise markedly under 5-HTP.

The enzyme that converts 5-HTP into serotonin works with vitamin B6 as a cofactor and occurs not only in the brain but also, for example, in the pancreas. Part of the 5-HTP is therefore already converted into serotonin in the rest of the body. In research, this peripheral conversion was slowed with the drug carbidopa, not with nutrients.

The third link, the assumption that a serotonin deficiency causes depression, is now disputed. An umbrella review of 17 reviews found no consistent evidence for this link. That does not mean 5-HTP cannot work. It means that the mechanism alone does not guarantee an effect.

What is well supported

The biochemistry is supported: in humans 5-HTP becomes serotonin, measurable in the blood, and it reaches the brain. For mood there is a long series of positive studies, most of them small and older. A 2020 meta-analysis arrived at a large effect on depression questionnaires across 7 studies (Hedges g 1.11), and the 2002 Cochrane review at a Peto odds ratio of 4.10 in favor of 5-HTP and tryptophan. In anxiety disorders, a double-blind study with 45 patients showed a moderate improvement compared with placebo.

There are also indications for sleep and appetite. In a randomized study from Singapore with 30 older adults, the subjective sleep score improved over 12 weeks, but only in those who slept poorly beforehand. In children with night terrors (pavor nocturnus), an open study reported that 29 of 31 treated children responded after one month. In a small double-blind study with 20 people with obesity, participants lost weight under 5-HTP and reported early satiety. A double-blind study with 50 patients with fibromyalgia described improvements in all symptoms assessed in 1990, with only mild side effects; the authors themselves called for further controlled studies.

What the studies show

Cochrane review 2002

The authors screened 108 studies on 5-HTP and tryptophan in depression. Only 2, with 64 patients in total, met the quality criteria. The result favored the active substances (Peto odds ratio 4.10; 95 percent confidence interval 1.28 to 13.15). The authors, however, consider the evidence too weak to derive a recommendation from it.

Meta-analysis Javelle 2020

13 investigations were analyzed, 7 of them in the meta-analysis. The pooled remission rate was 0.65, the effect on depression questionnaires Hedges g 1.11. Heterogeneity was high (I² 76 percent), and only a few studies had a placebo group. The authors therefore call for placebo-controlled studies with clearly defined diagnoses.

Truyens 2022, 166 patients

Multicenter, placebo-controlled crossover study at 13 Belgian hospitals in people whose inflammatory bowel disease was in remission but who suffered from fatigue. 8 weeks each of 5-HTP and placebo. Serum 5-HTP and serotonin rose markedly. The primary endpoint, fatigue reduced by at least 20 percent, was reached by 35.6 percent under 5-HTP and 37.6 percent under placebo. Mood, anxiety and stress did not differ either.

Singapore study 2024 and 2025

The same 30 older adults (66 ± 3 years), 12 weeks, single-blind, control group without placebo. Poor sleepers improved their sleep score, the cognitive test MoCA rose in the 5-HTP arm from 26.6 to 27.6 points, and the depression score fell from 1.2 to 0.7. The authors themselves urge caution because of the small numbers.

Where the data stop

The positive depression data come mostly from small, old studies without a placebo group. According to Cochrane, 2 placebo-controlled, methodologically sound studies with 64 patients remain. The newer positive studies are small, single-blind and without placebo. The two larger modern placebo studies were negative: in fatigue despite bowel disease (166 participants) and in distractibility with ADHD traits (112 participants, acute administration). So it is established that 5-HTP raises the serotonin level; that this translates into better well-being is not.

For sleep in adults there is exactly one small randomized study. On the question of whether 5-HTP should be paused after a few months there are no studies, nor are there long-term data on efficacy and safety. The EU rejected the health claims applied for on mood and weight reduction because of insufficient evidence. We found no verifiably documented user reports; this page therefore relies on studies and documented case reports.

Status, approval and legal

In Germany there is no approved medicine containing 5-HTP; Levothym was withdrawn from the market in 1992. Dietary supplements may contain Griffonia seeds and extracts with up to 30 percent 5-HTP. More highly concentrated extracts are considered unauthorized novel foods; in the first half of 2024 alone there were 4 EU alerts on this. The health claims applied for on mood and weight were rejected. Because 5-HTP is not an approved active substance, this page gives no dosage and no purchase recommendation. No relevance to doping is noted in the sources checked.

Safety

The most common complaints are nausea, vomiting, diarrhea, headache, insomnia and a racing heart; in the ADHD study, 19.6 percent of the 5-HTP group had fatigue, nausea or vomiting. Do not combine with antidepressants or other agents that act on serotonin, because of the risk of serotonin syndrome. Since the 1989 outbreak of eosinophilia-myalgia syndrome caused by contaminated L-tryptophan, 5-HTP has also been under observation. A 1994 case report describes a family whose 5-HTP contained a contaminant; a 2004 review found no comparable toxins in the preparations examined, and the Cochrane review considers the link unresolved. Another case report describes a 44-year-old man who suffered a reversible circulatory disorder in the memory center after ten times the dose. There are no safety data for pregnant women, breastfeeding women and children. We found no upper limit from EFSA, BfR or NIH. Preparations should be kept out of reach of pets; poisonings have been documented in dogs.

BK-Score Thin human evidence

Human evidence5
Mechanism6
Safety data4
Hype gap3
Track record of use6

The biochemistry has been shown in humans: 5-HTP crosses the blood-brain barrier (PET, 8 healthy people, 6 patients, Acta Psychiatr Scand 1991) and markedly raises serum 5-HTP and serum serotonin in randomized studies (Gastroenterology 2022; Clin Nutr 2024). Clinically the picture is mixed. For depression, the Cochrane review finds only 2 studies with 64 patients of sufficient quality among 108 studies (Peto OR 4.10; 95 % CI 1.28–13.15), and a meta-analysis (Nutr Rev 2020) arrives at Hedges g 1.11 across 7 studies, with I² 76 % and few placebo groups. Newer studies are small: 30 older adults, 12 weeks, single-blind, better sleep score only in poor sleepers. The largest modern placebo RCT (166 patients, 2 × 8 weeks) missed its primary endpoint of fatigue (35.6 vs. 37.6 percent) despite rising serotonin levels, and an acute RCT with 112 participants found no effect on distractibility. An umbrella review of 17 papers does not support the serotonin deficiency theory of depression (Mol Psychiatry 2023). On safety, only short-term data; according to Cochrane the EMS question after the 1989 L-tryptophan outbreak is unresolved, and documented are a family case with a contaminated preparation and the risk of serotonergic combinations.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about 5-HTP

Can you take 5-HTP together with antidepressants?

No, consumer advocates explicitly advise against it. SSRIs and other antidepressants also increase the action of serotonin; together there is a risk of serotonin syndrome, which can range from restlessness and tremor to serious complications such as seizures. Anyone taking medication should clear every combination with a doctor beforehand.

Does 5-HTP help you fall asleep?

There is an indication from a small study with 30 older adults in which poor sleepers improved their subjective sleep score. Placebo-controlled sleep studies in adults are missing. The mechanism via serotonin and melatonin is plausible; the clinical data are thin.

Does 5-HTP work against depression?

Older small studies show positive effects, but only 2 studies with 64 patients are methodologically sound and placebo-controlled. Depression belongs in medical treatment, and well-tested therapies exist for it. 5-HTP is not a proven substitute for them.

Is 5-HTP the same as tryptophan?

No. Tryptophan is the amino acid from food; 5-HTP is the next step on the way to serotonin. 5-HTP skips the slowest step of the synthesis and therefore acts more directly on the serotonin level.

Does 5-HTP help you lose weight?

A small double-blind study with 20 people with obesity found weight loss and earlier satiety. Larger studies are missing, and the EU rejected health claims on weight reduction because of insufficient evidence.

Is 5-HTP allowed in Germany?

As a dietary supplement, yes, as long as the Griffonia extract contains at most 30 percent 5-HTP. More strongly concentrated extracts are not authorized in the EU. A medicine containing 5-HTP has not been available in Germany since 1992.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-26.