Many antidepressant drugs work, at least in part, by raising serotonin levels. The supplement 5-hydroxytryptophan (5-HTP) has been tried in cases of depression for a similar reason: the body uses 5-HTP to make serotonin, so providing the body with 5-HTP might, therefore, raise serotonin levels.

As a supplement, 5-HTP has also been proposed for all the same uses as other antidepressants, including aiding weight loss, preventing migraine headaches, decreasing the discomfort of fibromyalgia, improving sleep quality, and reducing anxiety.


5-HTP is not found in foods to any appreciable extent. For use as a supplement, it is manufactured from the seeds of an African plant (Griffonia simplicifolia).

Therapeutic Dosages

A typical dosage of 5-HTP is 100 to 300 mg 3 times daily. Once 5-HTP starts to work, it may be possible to reduce the dosage significantly and still maintain good results.

Therapeutic Uses

The primary use of 5-HTP is for depression. Several small short-term studies have found that it may be as effective as standard antidepressant drugs.1,2 Since standard antidepressants are also used for insomnia and anxiety, 5-HTP has also been suggested as a treatment for those conditions, but there is only very preliminary evidence as yet that it works.3

Similarly, antidepressant drugs are often used for migraine headaches. Some, but not all, studies suggest that regular use of 5-HTP may help reduce the frequency and severity of migraines, as well as help other types of headaches.4-10 Additionally, preliminary evidence suggests that 5-HTP can reduce symptoms of fibromyalgia11 and perhaps help you lose weight.12-15 5-HTP has also been studied as a potential treatment for menopausal symptoms.

What Is the Scientific Evidence for 5-Hydroxytryptophan?

Several small studies have compared 5-HTP to standard antidepressants.16 The best one was a 6-week study of 63 people given either 5-HTP (100 mg 3 times daily) or an antidepressant in the Prozac family (fluvoxamine, 50 mg 3 times daily).17 Researchers found equal benefit between the supplement and the drug. However, 5-HTP caused fewer and less severe side effects.

There is some evidence that 5-HTP may help prevent migraines when taken at a dosage of 400 to 600 mg daily. Lower doses may not be effective.

In a 6-month trial of 124 people, 5-HTP (600 mg daily) proved equally effective as the standard drug methysergide.18 The most dramatic benefits observed were reductions in the intensity and duration of migraines. Since methysergide has been proven better than placebo for migraine headaches in earlier studies, the study results provide meaningful, although not airtight, evidence that 5-HTP is also effective.

Similarly good results were seen in another comparative study, using a different medication and 5-HTP (at a dose of 400 mg daily).19

However, in one study, 5-HTP (up to 300 mg daily) was less effective than the drug propranolol.20 Also, in a study involving children, 5-HTP failed to demonstrate benefit.21 Other studies that are sometimes quoted as evidence that 5-HTP is effective for migraines actually enrolled adults or children with many different types of headaches (including migraines).22,23,24

Putting all this evidence together, it appears likely that 5-HTP can help people with frequent migraine headaches if taken in sufficient doses, but further research needs to be done. In particular, we need a large double-blind study that compares 5-HTP against placebo over a period of several months.

Finally, an 8-week, double-blind, placebo-controlled trial of 65 individuals (mostly women) with tension headaches found that 5-HTP at a dose of 100 mg 3 times daily did not significantly reduce the number of headaches experienced; however, it did reduce participants' need to use other pain-relieving medications.25

The drug fenfluramine was one member of the now infamous phen-fen treatment for weight loss. Although very successful, fenfluramine was later associated with damage to the valves of the heart and was removed from the market. Because fenfluramine raises serotonin levels, it seems reasonable to believe that other substances that affect serotonin might also be useful for weight reduction.

Four small double-blind, placebo-controlled clinical trials examined whether 5-HTP can aid weight loss. The first, a double-blind crossover study, found that use of 5-HTP (at a daily dose of 8 mg per kilogram body weight) reduced caloric intake despite the fact that the 19 participants made no conscious effort to eat less.26 Participants given placebo consumed about 2,300 calories per day, while those taking 5-HTP ate only 1,800 calories daily. Use of 5-HTP appeared to lead to a significantly enhanced sense of satiety after eating. Over the course of 5 weeks, women taking 5-HTP effortlessly lost more than 3 lbs.

A follow-up study by the same research group enrolled 20 overweight women who were trying to lose weight.27 Participants received either 5-HTP (900 mg per day) or placebo for two consecutive 6-week periods. During the first period, there was no dietary restriction, while during the second period participants were encouraged to follow a defined diet expected to lead to weight loss.

Participants receiving placebo did not lose weight during either period. However, those receiving 5-HTP lost about 2% of their initial body weight during the no-diet period and an additional 3% while on the diet. Thus, a woman with an initial weight of 170 lbs lost about 3-1/2 lbs after 6 weeks of using 5-HTP without dieting and another 5 lbs while dieting. Once again, participants taking 5-HTP experienced quicker satiety.

Similar benefits were seen in a double-blind study of 14 overweight women given 900 mg of 5-HTP daily.28

Finally, a double-blind, placebo-controlled study of 20 overweight individuals with adult-onset diabetes found that use of 5-HTP (750 mg per day) without intentional dieting resulted in about a 4-1/2 lb weight loss over a 2-week period.29 Use of 5-HTP reduced carbohydrate intake by 75% and fat intake to a lesser extent.

Antidepressants are the primary conventional treatment for fibromyalgia, a little-understood disease characterized by aching, tender muscles, fatigue, and disturbed sleep. One study suggests that 5-HTP may be helpful as well. In this double-blind trial, 50 subjects with fibromyalgia were given either 100 mg of 5-HTP or placebo 3 times daily for a month.30 Those receiving 5-HTP experienced significant improvements in all symptom categories, including pain, stiffness, sleep patterns, anxiety, and fatigue.

An 8-week, double-blind, placebo-controlled study compared 5-HTP and the drug clomipramine in 45 individuals suffering from anxiety disorders.31 The results showed that 5-HTP was effective, but clomipramine was more effective.

In a small study, 24 menopausal women were randomized to receive 5-HTP (150 mg once per day) or placebo. The researchers, using a special device to measure the women's hot flashes, found that the subjects who took 5-HTP experienced no reduction in the frequency of hot flashes compared to placebo.52

Safety Issues

No significant adverse effects have been reported in clinical trials of 5-HTP. Side effects appear to be generally limited to short-term, mild digestive distress and possible allergic reactions.

One potential safety issue with 5-HTP involves an interaction with a medication used for Parkinson's disease: carbidopa. Several reports suggest that the combination can create skin changes similar to those that occur in the disease scleroderma.32,33,34

According to several reports, when dogs have consumed excessive amounts of 5-HTP, they developed signs of excess serotonin.39 In humans, this so-called serotonin syndrome includes such symptoms as confusion, agitation, rapid heart rate, high blood pressure, muscle jerks, loss of coordination, sweating, shivering, and fever; rapid breathing, coma, and death are possible. Serotonin syndrome might also occur if 5-HTP is combined with drugs that raise serotonin levels, such as SSRIs (such as, Prozac), other antidepressants, or the pain medication tramadol.

There are some reasons for concern that 5-HTP could increase the risk of “infantile spasms” (technically, massive myoclonic seizure disorder) in developmentally disabled children.35,40

Although safety in children has not been proven, children have been given 5-HTP in studies without any apparent harmful effects.36,37,38 Safety in pregnant or nursing women and those with liver or kidney disease has not been established.

Peak X

One report in 1998 raised a potential safety concern with 5-HTP. Researchers discovered evidence of an unidentified substance called peak X in a limited number of 5-HTP products.41

Peak X has a frightening history involving a supplement related to 5-HTP: tryptophan. The body turns tryptophan into 5-HTP, and the two supplements have similar effects in the body. Until the late 1980s, tryptophan was widely used as a sleep aid. However, it was taken off the market when thousands of people using tryptophan developed a disabling and sometimes fatal blood disorder called eosinophilia myalgia. Peak X, introduced through a manufacturer's mistake, is thought to have been the cause, although not all experts agree.42-50

Despite this one report, it seems unlikely that 5-HTP could present the same risk as tryptophan.51 It is manufactured completely differently; peak X has not been seen again in 5-HTP samples, and no epidemic of eosinophilia myalgia has occurred with 5-HTP use.

Interactions You Should Know About

If you are taking:

  • Prescription antidepressants (including SSRIs, MAO inhibitors, or tricyclics), the pain drug tramadol, or migraine drugs in the triptan family (such as sumatriptan): Do not take 5-HTP in addition, except on a physician's advice.
  • The Parkinson's disease medication carbidopa: Taking 5-HTP at the same time might cause skin changes similar to those that develop in the disease scleroderma.