FM/CFS/ME RESOURCES - Drug Database - 5-HTP


Search Site 
Disability Attornies
Find A Doctor
Drugs Used In FM & CFS/ME
In-Person Support Groups

Archived Poll Results
Candles of Hope
CMP Info.
Family and Friends
Financial Help
Letter To Loved Ones
Living With FM & CFS/ME
Newly Diagnosed
Rate Your Meds  -  Results
Recommend Doctor
Researchers Spotlight

Take Quiz
Quiz Winners
Patient Surveys

Drug Database - 5-HTP 5-HTP

Other Names: 5 hydroxy-tryptophan, 5-hydroxytryptophan, 5-hydroxy L-tryptophan, 5-Hydroxy Tryptophan, 5-L-Hydroxytryptophan, L-5 HTP, L-5 hydroxytryptophan, Oxitriptan.

Classification: Chemical By-Product / Nutritional Supplement

5-HTP (5-Hydroxytryptophan) is a chemical by-product of the protein building block L-tryptophan. It is also produced commercially from the seeds of an African plant (Griffonia simplicfolia).

5-HTP is used by the human body to make serotonin, an important substance for normal nerve and brain function. Serotonin appears to play significant roles in sleep, emotional moods, pain control, inflammation, intestinal peristalsis, and other body functions.

Return to top of page


During the clinical trials described above, some people taking large amounts of 5-HTP experienced gastrointestinal upset (e.g. nausea) or, less often, headache, sleepiness, muscle pain, or anxiety.

A substance known as "Peak X" has been found in low concentrations in several over-the-counter 5-HTP preparations. Some researchers think this substance may be linked to toxicity previously reported in a 1989 L-tryptophan contamination incident. However, there is serious question about whether Peak X is actually the toxic agent and it may be unrelated to the problems previously associated with L-tryptophan. Although two articles reported possible associations between 5-HTP consumption and toxicity symptoms similar to those attributed to contaminated L-tryprophan, evidence linking 5-HTP or Peak X with any toxicity symptoms remains speculative. Although the structure of Peak X has recently been identified, there is no firm evidence that this substance has caused or contributed to any toxicity or disease.

Very high intakes of 5-HTP have caused muscle jerks in guinea pigs and both muscle jerks and diarrhea in mice. Injected 5-HTP has also caused kidney damage in rats. To date, these problems have not been reported in humans. "Serotonin syndrome," a serious but uncommon condition caused by excessive amounts of serotonin, has not been reported to result from supplementation with 5-HTP; in theory it could be triggered by the supplement. However, the level of intake at which this toxic effect might potentially occur remains unknown.

Do NOT take 5-HTP capsules if you suffer from any of the following:

  • Cardiovascular Diseases (post-stroke, high blood pressure, post-heart attack)
  • Extremely Elderly Persons
  • Those with Parkinson's Disease
  • Those with Cancer
  • Those with Autoimmune Diseases:
    • Scleroderma
    • Arthritis
    • Rheumatoid Arthritis
    • Lupus
    • Multiple Sclerosis

  • Those with Lung Diseases
  • Those with Chronic Alcoholism; Liver diseases (hepatitis or cirrhosis)
  • Those with parasitic infection
  • Those with AIDS
  • Those with Anorexia Nervosa
  • Those with Low protein Diets
  • Those with Allergies (severe)
  • Those with Myalgia (persistent pain and weakness of the muscles)
  • Those with Peripheral Neuropathy (pain weakness of the muscles)
  • Those with Rash or Flushing
  • Those with Edema
  • Those with Nausea; Diarrhea
  • Those with Sickle cell anemia
  • Those with hemophilia
  • Those who are Pregnant

Do NOT take 5-HTP capsules if you are taking any of the following:

  • Anti-depressant drugs
  • Monoamine oxidase inhibitors
  • Selective Serotonin Reuptake Inhibitors (SSRI's e.g., Prozac);
  • Tricyclic medications
  • Weight Loss medications (i.e., dextenfluramine)
  • Anti-parkinson medications (e.g., L-dopa)
  • Barbiturates and other tranquilizing drugs
  • Antihistamines and cold medications
  • Alcoholic beverages
  • Intravenous (illegal I.V.) drugs
  • Cancer chemotherapy
  • Antibiotic medications

Avoid prolonged exposure to sunlight. 5-hydroxytryptophan may increase the sensitivity of your skin to the sun. Use a sunscreen and wear protective clothing when exposure to the sun is unavoidable.

Return to top of page

Side Effects

5-HTP was released in 1994, and long term effects, or the effects of long term use, are still unknown. It is thought, that in safe doses, that there will be no, or little long term side effects, as all the capsules do is restore a depleted natural chemical in the body, but the effects of extreme doses are unknown.

What is known are the short term possible side effects: (These have been shown in higher dosages, typically over 100mgs)

  • nausea
  • vomiting
  • stomach cramps
  • nightmares
  • decreased sex drive
  • constipation
  • gas
  • drowsiness

Other side effects reported in large dosages (100MG+) include nightmares. It is however, worth noting that side effects are reported to be fewer, and more unlikely then when taking a traditional antidepressant.

Dosages of 5-HTP greater than 100MG per day should only be taken under the guidance of your Physician. -- There is a very serious reason for this, please read below:

Serotonin Syndrome:

This dangerous and a potentially FATAL condition usually occurs when your body contains too much Serotonin, as a result from serotonergic enhancing drugs, but can also be a result of taking too many drugs that increase your Serotonin at the same time, such as being on a Selective Serotonin Reuptake Inhibitor (SSRI e.g., Prozac); Tricyclic medications, at the same time.

Signs of Serotonin Syndrome include:

  • euphoria
  • drowsiness
  • sustained rapid eye movement
  • overreaction of the reflexes
  • rapid muscle contraction and relaxation in the ankle causing abnormal movements of the foot
  • clumsiness
  • restlessness
  • feeling drunk and dizzy
  • muscle contraction and relaxation in the jaw
  • sweating
  • intoxication
  • muscle twitching
  • rigidity, high body temperature

Return to top of page


In a controlled trial, 5-HTP (300 mg per day) was shown to be effective in reducing many symptoms of fibromyalgia, including pain, morning stiffness, sleep disturbances, and anxiety.

For depression, 300 mg per day is often effective, though much of the research used 5-HTP in combination with drugs or was uncontrolled.

For insomnia, a single 100-mg nighttime dose of 5-HTP was sufficient to improve the duration and depth of sleep in one placebo-controlled trial.

For migraine headaches, amounts ranging from 400–600 mg per day have been shown to be effective at reducing the frequency and severity of attacks in most clinical trials.

For tension headaches, 100 mg of 5-HTP taken three times per day led to a significant decrease in consumption of pain-relievers, but no significant change in headache duration or intensity.

Appetite reduction and weight loss (averaging 11 pounds in 12 weeks) has occurred with amounts of 600–900 mg daily. In another clinical trial, 750 mg per day has been shown to be effective at decreasing carbohydrate and fat intake, and promoting weight loss.

Return to top of page

Drug Interactions

Certain medicines interact with 5-hydroxytryptophan: Some interactions may increase the need for 5-hydroxytryptophan (Beneficial), other interactions may be negative (Avoid) and indicate 5-hydroxytryptophan should not be taken without first speaking with your physician or pharmacist, others may require further explanation (Check).

  • Carbidopa - Check
  • Carbidopa/Levodopa - Check
  • Fluoxetine - Avoid
  • Fluvoxamine - Avoid
  • Paroxetine - Avoid
  • Sertraline - Avoid
  • Sibutramine - Avoid
  • Sumatriptan - Avoid
  • Tramadol - Avoid
  • Venlafaxine - Avoid
  • Zolmitriptan - Avoid
  • Zolpidem - Avoid

Return to top of page


  •, 5 HTP --- Side Effects.

  • Belongia EA, Hedberg CW, Gleich GJ, et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J Med 1990;323:357–65.

  • Martin RW, Duffy J, Engel AG, et al. The clinical spectrum of the eosinophilia-myalgia syndrome associated with L-tryptophan ingestion. Clinical features in 20 patients and aspects of pathophysiology. Ann Intern Med 1990;113:124–34.

  • Mayeno AN, Lin F, Foote CS, et al. Characterization of "peak E," a novel amino acid associated with eosinophilia-myalgia syndrome. Science 1990;250:1707–8.

  • Belongia EA, Hedberg CW, Gleich GJ, et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J Med 1990;323:357–65.

  • Reinauer S, Plewig G. [Eosinophilia-myalgia syndrome]. Hautarzt 1991;42(3):137–9 [in German].

  • Toyo'oka T, Yamazaki T, Tanimoto T, et al. Characterization of contaminants in EMS-associated L-tryptophan samples by high-performance liquid chromatography. Chem Pharm Bull (Tokyo) 1991;39(3):820–2.

  • Trucksess MW, Thomas FS, Page SW. High-performance liquid chromatographic determination of 1,1'-ethylidenebis(L-tryptophan) in L-tryptophan preparations. J Pharm Sci 1994;83(5):720–2.

  • Trucksess MW. Separation and isolation of trace impurities in L-tryptophan by high-performance liquid chromatography. J Chromatogr 1993;630(1–2):147–50.

  • Ito J, Hosaki Y, Torigoe Y, Sakimoto K. Identification of substances formed by decomposition of peak E substance in tryptophan. Food Chem Toxicol 1992;30(1):71–81.

  • Castot A, Bidault I, Bournerias I, et al. ["Eosinophilia-myalgia" syndrome due to L-tryptophan containing products. Cooperative evaluation of French Regional Centers of Pharmacovigilance. Analysis of 24 cases]. Therapie 1991;46(5):355–65.

  • Michelson D, Page SW, Casey R, et al. An eosinophilia-myalgia syndrome related disorder associated with exposure to L-5-hydroxytryptophan. J Rheumatol 1994;21:2261–5.

  • Sternberg EM, Van Woert MH, Young SN, et al. Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J Med 1980;303(14):782–7.

  • Johnson KL, Klarskov K, Benson LM, et al. Presence of peak X and related compounds: the reported contaminant in case related 5-Hydroxy-L-tryptophan associated with eosinophilia-myalgia syndrome. J Rheumatol 1999;26(12):2714–7.

  • Hagan JJ, Hatcher JP, Slade PD. The role of 5-HT1D and 5-HT1A receptors in mediating 5-hydroxytryptophan induced myoclonic jerks in guinea pigs. Eur J Pharmacol 1995;294:743–51.

  • Green AR, Johnson P, Mountford JA, Nimgaonkar VL. Some anticonvulsant drugs alter monoamine mediated behaviour in mice in ways similar to electroconvulsive shock; implications for antidepressant therapy. Br J Pharmacol 1985;84:337–46.

  • Bourin M, Hascoet M, Deguiral P. 5-HTP induced diarrhea as a carcinoid syndrome model in mice? Fundam Clin Pharmacol 1996;10:450–7.

  • Hirai M, Nakajima T. Biochemical studies on the mechanism of difference in the renal toxicity of 5-hydroxy-L-tryptophan between Sprague Dawley and Wistar rats. J Biochem (Tokyo) 1979;86:907–13.

  • Martin TG. Serotonin syndrome. Ann Emerg Med 1996;28:520–6.

  • Sternberg EM, Van Woert MH, Young SN, et al. Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J Med 1980;303:782–7.
Return to Top