5-HTP is sold over the counter in the United Kingdom, United States and Canada as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid, and is also marketed in many European countries for the indication of major depression under trade names like Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum.^[1][2] Several double-blind placebo-controlled clinical trials have demonstrated the effectiveness of 5-HTP in the treatment of depression,^[1] though a lack of high quality studies has been noted.^[3] More and larger studies are needed to determine if 5-HTP is truly effective in treating depression.^[4]

Though 5-HTP is found in food only in insignificant quantities, it is a chemical involved intermediately in the metabolism of tryptophan, an amino acid found in milk, meat, potatoes, pumpkin, and various greens.^[14] See also the section Dietary sources of the article on L-tryptophan.

Therapeutic use[edit]

5-HTP is sold over-the-counter in the United States, the United Kingdom, and Canada as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. 5-HTP in supplement form is typically sold in 50 mg or 100 mg gelatin or vegetarian capsules. It is usually sourced from the seeds of Griffonia simplicifolia.

5-HTP has been studied and shown to be of benefit^{[clarification needed]} in the following conditions: primary fibromyalgia syndrome,^[15] Friedreich's ataxia,^[16] anxiety, binge eating associated with obesity, and insomnia.^[17] There is no statistically significant difference between 5-HTP and placebo in treating chronic headaches (primary or otherwise).^[18]

In 2001 a Cochrane Review of the effect of 5-HTP and tryptophan on depression was published. The authors included only studies of a high rigor and included both 5-HTP and tryptophan in their review because of the limited data on either. Of 108 studies of 5-HTP and tryptophan on depression published between 1966 and 2000, only two met the authors' quality standards for inclusion, totaling 64 study participants. The substances were more effective than placebo in the two studies included but the authors state that, "the evidence was of insufficient quality to be conclusive," and note, "because alternative antidepressants exist which have been proven to be effective and safe, the clinical usefulness of 5-HTP and tryptophan is limited at present."^[3]

5-HTP is often taken by people coming down from MDMA to relieve post-MDMA dysphoria. The basis for doing this is that 5-HTP is a necessary precursor for the brain to produce more serotonin, and MDMA use depletes a person's natural serotonin levels, thus taking 5-HTP after a dose of MDMA could improve serotonin production.^{[citation needed]} While the practice is common, no verifiable evidence could be found to confirm whether the practice actually works.