Product Information

Synonyms: 5-Hydroxytryptophan

Keywords: mood, depression, insomnia, obesity, appetite, fibromyalgia, migraine, coughing


5-HTP (5-hydroxy-L-tryptophan) is the substance that the brain uses to make serotonin — a neurotransmitter that regulates emotions, sleep-wake cycles, appetite, and general feelings of well-being.1

When the body’s serotonin levels are inadequate, the result can be depression, excessive eating, and sleep disorders. Serotonin deficiencies may also play a role in migraine headaches, fibromyalgia, panic attacks, delirium tremens, sleep terrors, and coughing.

What we can’t tell you

In the U.S. and some other industrialized countries, government agencies like the U.S. Food and Drug Administration have adopted censorship as a method for intensifying their control over the supplement industry and its customers. Thus, FDA regulations prohibit us from telling you that any of our products are effective as medical treatments, even if they are, in fact, effective.

Accordingly, we will limit our discussion of 5-HTP to a brief summary of relevant research, and let you draw your own conclusions about what medical conditions it may be effective in treating.

General remarks

A good, brief summary of 5-HTP as a treatment for various conditions is the one by Birdsall in the abstract to his 1998 review.1 A more detailed summary is the one provided by Thorne Research, Inc.2

Most, if not all, studies of 5-HTP as medical treatments are based on the concept that the underlying medical conditions involve serotonin. The treatments depend on the fact that 5-HTP crosses the blood-brain barrier and is then converted into serotonin.

Although many physicians believe that 5-HTP supplementation will not raise serotonin levels unless combined with a drug like carbidopa — to prevent 5-HTP from being metabolized before it reaches the nervous system — this notion has been refuted by experiments with oral 5-HTP in both rats and humans. When used orally, without the aid of other drugs, 5-HTP does significantly raise serotonin levels in the brain.3

On the other hand, it has been suggested that the metabolism of 5-HTP outside the brain may be accelerated if 5-HTP is used in combination with vitamin B6.21 Little has been done to examine this issue, so to be on the safe side, it would make sense to avoid B6 supplements on days when one is using 5-HTP.

The dosages of 5-HTP used in most clinical trials range from 100 mg/day in children to as much as 400 mg/day in adults. These daily dosages are usually divided into three spaced doses about 8 hours apart. The exception is in the use of 5-HTP for insomnia, where the daily dosage is taken all at once, before bedtime. Clinicians usually design 5-HTP regimens that start with a ramping-up period, using smaller doses for two weeks.2

5-HTP is well absorbed whether it is taken with food or by itself.2

5-HTP and depression

5-HTP has been of interest as an antidepressant for several decades. It has shown good results in a number of clinical trials, and given null results in others.4 A meta-analysis done on this medical literature in 2002 resulted in a claim that all of the clinical trials published up to that time were of poor quality and allowed no conclusions to be drawn.5 On the other hand, critics of such meta-analyses say that these analyses are the products of extreme and obsessive statistical finickiness and that they ‘throw the baby out with the bathwater’.

It is true, in any case, that clinical studies and very large numbers of anecdotal reports attest to the effectiveness of 5-HTP as an antidepressant in some people. (The same can be said of prescription antidepressants, such as fluoxetine (Prozac®) and paroxetine (Paxil®) — they are effective for some, and ineffective for others. Patients often have to try a series of these drugs before finding one that works.)

5-HTP and appetite

The ability of 5-HTP to inhibit appetite was first noted in rats in 1964.6 The mechanism appears to involve the raising of serotonin levels. Several dozen research papers on the subject have appeared since then, including a few reports of clinical trials both in diabetic patients and in obese patients without diabetes,7,8 with the result that 5-HTP is widely regarded as effective in reducing the appetite and bodyweight of people who overeat.4 Nevertheless, the medical profession has preferred much more expensive treatments with prescription drugs, some of which have proved to be harmful to patients.9

5-HTP and sleep disorders

The effects of 5-HTP on sleep date from 1971,10 when it was studied as a treatment for insomnia. Despite the encouraging results of early studies,2,11 and countless positive anecdotal reports over the years, medical research has almost completely ignored it as an insomnia treatment.

In a clinical trial in 2004 researchers reported that 5-HTP is a very effective treatment for sleep terrors in children.12 After six months, 84% of the patients who used 5-HTP at 2 mg/kg were free of sleep terrors, as compared with only 28% of the comparison group. Sleep terrors (a.k.a. ‘night terrors’) are a type of nightmare from which it is difficult to awaken.13

5-HTP and fibromyalgia

Fibromyalgia is an ailment characterized by musculoskeletal pain (both diffuse and localized), fatigue, lowered pain thresholds, and nonrestorative sleep. Multiple lines of evidence suggest that a decline in serotonin production may be involved.14 Clinical trials in fibromyalgia patients in the early 1990s demonstrated significantly lessened symptoms.15,16 Since that time, little or no research work has been done to follow up on these promising leads.

5-HTP and migraine

5-HTP was first reported to improve migraine headaches in the early 1970s.17 Since then, several dozen reports have been published on the subject, and almost a dozen clinical trials have been conducted — most of them showing some efficacy of 5-HTP for prevention of migraines and other headaches.2 Dosages ranged from 100 mg/day in children to 400 mg/day in adults, in divided doses.

5-HTP and panic attacks

In a 2004 clinical study, panic disorder patients were made to breathe a 35% atmosphere of carbon dioxide, which typically induces a panic reaction. Those who had been pretreated with 200 mg of 5-HTP had significantly reduced panic symptoms compared with those treated with placebo.18

5-HTP and coughing

Serotonin acts as a modulator of the cough reflex. With this in mind, researchers in 1986 showed that 5-HTP had the ability to depress the cough reflex in cats.19 In 1993 a similar result was shown in humans.20 In these experiments the 5-HTP was administered intravenously, but there is no reason to think that oral supplementation would not have similar effects, since the key element is the conversion of 5-HTP to serotonin in the brain — which occurs whether 5-HTP is taken orally or intravenously.


Are 5-HTP supplements useful for the conditions and purposes mentioned above? We aren’t allowed to tell you, so you should take a look at some of the references cited here, and then decide for yourself.

10102 50 mg 60 capsules 1-6 capsules $16.06
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10104 100 mg 30 capsules 1-3 capsules $16.06
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10105 100 mg 60 capsules 1-3 capsules $29.44
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10106 25 mg 90 lozenges 1-6 lozenges $16.70
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Pronunciation: hydroxytryptophan hæ·drăxʹ·ē·trıpʹ·tō·fan

— RM

Last modified 2010.09.01