5-HTP: What Is Known, and the Serotonin Medicine Cautions

By The Kasivit Editorial Team · Library · November 2026

5-HTP (5-hydroxytryptophan) is the step between the amino acid tryptophan and serotonin, a messenger linked to mood and sleep. It often comes up when women talk about the mood and sleep changes of the years around menopause. Here is what the research shows, how little of it involves the menopausal transition, and why anyone taking a serotonin-acting medicine should talk to a prescriber or pharmacist before combining it with 5-HTP.

General information, not medical advice.

What 5-HTP is, and why it matters for medicines

Your body makes serotonin from tryptophan, which comes from protein in food. Tryptophan is first turned into 5-HTP, and 5-HTP is then turned into serotonin. A 2006 review of 5-HTP in Pharmacology and Therapeutics explained that, without a supplement, how much 5-HTP is available depends on how much tryptophan you have and on the activity of several enzymes. It also noted that a good share of swallowed 5-HTP can be converted to serotonin outside the brain, and that medicines called peripheral decarboxylase inhibitors, such as carbidopa, can block that conversion.¹

In other words, 5-HTP feeds directly into the serotonin system that many prescription medicines act on. The review gave particular attention to two safety issues, serotonin syndrome and eosinophilia-myalgia syndrome, both covered below.¹

Mood and the menopausal transition: setting the scene

Many women describe changes in mood, sleep and energy during perimenopause and after the final period. Because serotonin is involved in mood and sleep, a serotonin building block is easy to market here, but a plausible mechanism is not evidence. Searching PubMed, we found one small randomized trial of 5-HTP in postmenopausal women, and it looked at hot flashes, not mood or sleep. We found no trial of 5-HTP for mood or sleep in women in perimenopause. Most of what follows comes from other groups and should not be assumed to apply to the menopausal transition.

The evidence at a glance

5-HTP and low mood: what the reviews found

The Cochrane review

A Cochrane systematic review asked whether 5-HTP and tryptophan work better than placebo for depression in adults, and whether they are safe. The reviewers located 108 trials, but only two, with a total of 64 patients, were of sufficient quality to be included. Results for 5-HTP and tryptophan were combined because there were so few trials. In that small pool, the supplements were better than placebo at easing depression (Peto odds ratio 4.10; 95% confidence interval 1.28 to 13.15).²

The reviewers wrote that the evidence was of insufficient quality to be conclusive, that more studies of efficacy and safety were needed before widespread use could be recommended, and that because proven antidepressants existed, the clinical usefulness of 5-HTP and tryptophan was limited.² The full text shows that only one of the two included trials tested 5-HTP. The very wide confidence interval reflects how little data sits behind the result.

A later meta-analysis

A 2020 systematic review and meta-analysis in Nutrition Reviews searched the literature up to May 2018. It included 13 investigations in the review and 7 in the full meta-analysis. The pooled depression remission rate was 0.65 (95% CI 0.55 to 0.78), and questionnaire results showed a large effect size (Hedges' g 1.11; 95% CI 0.53 to 1.69).³

Those figures sound encouraging, but the same paper explains why they need caution. The studies differed in how long people took 5-HTP, the type of depression studied, design, and dose, and this showed up as high variability between results (I2 = 76%). A formal risk-of-bias tool rated current studies as relatively weak overall, and few included placebo groups.³ Without a placebo group, some improvement can come from time, other care, or expecting to feel better.

Menopause and sleep: the thin evidence

Hot flashes in postmenopausal women

The only randomized trial of 5-HTP in menopausal women that we found was a small double-blind study. Its author noted that SSRI medicines, which raise serotonin levels between nerve cells, had shown some promise for hot flashes, and asked whether 5-HTP might do something similar. Twenty-four postmenopausal women reporting frequent hot flashes took 5-HTP or a placebo, and hot flashes were counted with a small electronic recorder rather than a diary. At 150 mg/day, 5-HTP had no significant effect on hot flash frequency. The author described the study as preliminary because of its small size.⁴ Per the full text, capsules were taken for about a month. Mood and sleep were not measured, and no women in perimenopause took part.

Sleep in older adults

A 2024 randomized trial in Singapore assigned 30 older adults (average age 66, give or take 3 years) to take or not take 100 mg of 5-HTP daily for 12 weeks. Sleep was measured by questionnaire (the Pittsburgh Sleep Quality Index) and an activity-tracking watch. The authors reported a favorable effect on certain parts of sleep quality and higher blood serotonin. The questionnaire improvement was statistically significant only in people who were poor sleepers at the start (p = 0.005), not in good sleepers.⁵

The trial was single-blinded, and the comparison group took nothing, so there was no placebo, which matters for a self-rated outcome like sleep quality. The abstract does not report results for women or by menopausal stage.⁵

Serotonin syndrome and medicine interactions

Serotonin syndrome is a potentially life-threatening reaction caused by overstimulation of serotonin receptors by serotonin-acting drugs. A 2023 review by clinical pharmacologists in Denmark explained that it can occur with normal use or overdose of one such drug, or through an interaction between two or more. Its central features are neuromuscular excitation, autonomic dysfunction (the body's automatic functions, such as heart rate and temperature), and altered mental status, typically in someone who has recently started or changed a serotonin-acting therapy. The authors noted that cases have likely risen with the widespread use of SSRIs and that the true incidence is unknown.⁶

The 2006 5-HTP review listed serotonin syndrome as one of the main safety issues with 5-HTP.¹ Put simply, 5-HTP adds to the serotonin supply, so combining it with a medicine that also raises serotonin activity may add to the risk.

The eosinophilia-myalgia question

Both the 2006 review and the Cochrane review raised eosinophilia-myalgia syndrome (EMS), a serious condition affecting muscles and blood cells. The Cochrane reviewers described the possible link between these substances and the potentially fatal syndrome as not yet explained.^1,2 The Cochrane full text describes an outbreak among tryptophan users in the late 1980s, an impurity found in some of those products, and reports of a similar impurity in 5-HTP, with the cause still uncertain. It also notes that nausea and stomach upset are the most notable side effects, and that systematic long-term safety studies of 5-HTP did not exist.

Who paid for these studies?

Funding does not decide whether a study is right, but it is useful context. This is what we could confirm from the full text, where it was open access, and from PubMed otherwise.

• Shaw 2001 Cochrane review. The full text lists internal support from the Royal Australian College of General Practitioners and no external sources of support. The authors declared no interests.²
• Freedman 2010 hot flash trial. The full text states that the work was funded by a grant from the US National Institute on Aging. The 5-HTP capsules were bought from a commercial supplement manufacturer, which also provided a certificate of analysis, and a pharmacist repackaged them into blinded bottles alongside matching placebo capsules.⁴
• Sutanto 2024 sleep trial. Europe PMC lists the National University of Singapore as the funder. We could not read the full text, so we cannot say who supplied the 5-HTP, and the PubMed conflict-of-interest field gives no detail.⁵
• Turner 2006 review, Javelle 2020 meta-analysis and Mikkelsen 2023 review. Funding was not stated in what we could access (the PubMed records and abstracts), and we could not read the full texts.^1,3,6

Limits of the research

• Very few good trials. The Cochrane review found only two trials of sufficient quality out of 108 located, and the 2020 meta-analysis rated the studies as relatively weak.^2,3
• Missing placebo groups. Few depression studies had placebo groups, and the sleep trial had none.^3,5
• Small samples. The menopause and sleep trials had 24 and 30 participants.^4,5
• Wrong population for the question. No trial we found tested 5-HTP for mood or sleep in women in perimenopause. The only menopause trial measured hot flashes and found no significant effect.
• Short duration and unknown long-term safety. The trials ran for weeks to a few months, and the Cochrane reviewers noted that systematic long-term safety studies did not exist.
• Different doses and products. Doses and study designs varied, which the 2020 authors linked to the high variability in results.³

Food, sleep habits and your clinician come first

Tryptophan comes from protein foods such as dairy, eggs, poultry, fish, beans, nuts and seeds. Regular meals, daylight, activity and a steady sleep routine are reasonable starting points when sleep or mood shifts.

Mood changes during perimenopause deserve a real conversation with a clinician. Persistent low mood, anxiety or poor sleep can have several causes, and there are well-studied options to discuss, including hormonal and non-hormonal approaches, talking therapies and medicines. If you ever have thoughts of harming yourself, seek urgent help right away.

How to read a 5-HTP label

The Supplement Facts panel tells you what is in a product, not whether it suits you. The same checks apply to any product, including our 5-HTP.

Source and amount

Many 5-HTP products are made from the seeds of Griffonia simplicifolia, a West African plant. Check the amount per serving, which may be one capsule or several, and add up 5-HTP from every product you take.

Combination formulas

5-HTP is often combined with melatonin, herbal extracts or other amino acids, some of which may also affect serotonin or drowsiness. Read the full ingredient list and bring the bottle to your pharmacist.

Quality marks

Third-party testing seals relate to checks on contents and purity, not to health effects, and they do not change the medicine-interaction question.

Safety and who should check first

• Know the warning signs. Serotonin syndrome can involve muscle overactivity, changes in automatic body functions such as heart rate and temperature, and changes in mental state, usually soon after a new or changed serotonin-acting therapy.⁶ If you notice symptoms like these, seek medical care promptly and bring your products with you.
• Tell your care team. List every supplement you take at each appointment and before any procedure.
• Keep supplements away from children. Store all supplements out of reach and sight of children.

The short version

Reviews of 5-HTP in depression reported favorable pooled results, but the trials are few, small, often without a placebo group, and judged weak or inconclusive by their own reviewers. The only menopause trial we found looked at hot flashes and found no significant effect, and we found no trials in perimenopausal women for mood or sleep. Because 5-HTP adds to the serotonin system, anyone taking a serotonin-acting medicine should talk to a prescriber or pharmacist before combining them.