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Latest Edit: Iva Lloyd, ND 2017-05-05 (EDT)

5-Hydroxytryptophan (L-5-hydroxytryptophan, or 5-HTP) is a metabolite of L-tryptophan and an immediate precursor to serotonin. The rate-limiting step in serotonin synthesis involves the enzyme Tryptophan hydroxylase, which converts L-tryptophan to 5-HTP. Serotonin synthesis may in some circumstances be enhanced to a greater extent by administering 5-HTP over L-tryptophan.[1]


The following is a list of uses for 5-HTP:[2]

  • Cerebellar ataxia: Studies have reported that some features of cerebellar ataxia have been found to regress with long-term administration of 5-HTP. Such features include improvements in time of standing upright, the spread of feet, the speed of walking, speaking, and writing.[3]
  • Depression: Oral adminitration of 5-HTP has been found to significantly improve symptoms of depression. There is also evidence that 5-HTP may be comparable to conventional antidepressants such as fluvoxamine (Luvox) and imipramine (Tofranil).[2]
  • 5-HTP is a precursor to serotonin.
  • Fibromyalgia: Studies have found that taking 5-HTP orally can improve symptoms of primary fibromyalgia syndrome, including pain severity, morning stiffness and sleeplessness.[2]
  • Insomnia: Serotonin levels have been implicated in the regulation of sleep, among other things. Studies indicate that therapeutic doses of 5-HTP has been shown to be effective in treating a wide range of conditions including insomnia.[4]
  • Migraine: 5-HTP has been found to induce a significant decrease in migraines. Results from studies suggest that central nervous system abnormalities underlying the mechanism of migraine can be changed by 5-HTP[5]
  • Sleep terrors: Some studies have revealed that treatment with L-5-Hydroxytryptophan is able to modulate the arousal level in children and can induce long-term improvement of sleep terrors[6]

Prescribing Considerations

The recommended dosages have not yet been established. To determine what your specific requirements are talk to your naturopathic doctor or other trained medical professional.[1]

  • Commonly used dosages of 5-HTP are 50-100mg 3 times per day.
  • Depression: 150-300 mg daily [2]
  • Fibromyalgia: 100 mg 3 times daily [2]
  • Sleep terrors:
  • Child: 2mg/kg of body weight at bedtime
  • Cerebellar ataxia, 1,000mg/day

Ingesting 5-HTP at the same time as a protein-containing meal might decrease its effectiveness.


The safety precautions of 5-HTP include[1]:

  • Side effects such as nausea, diarrhea, abdominal pain, heartburn, myalgias, headache, drowsiness, and parasthesias.
  • Adverse Effects:Excessive doses may cause nystagmus, listlessness, euphoria, hyperactivity, inappropriate behaviour, and in certain types of psychiatric patients, sexual disinhibition.
  • Interactions:
  • Co-administration of 5-HTP and antidepressants that increase serotogenic activity (such as selective serotonin reuptake inhibitors [SSRIs], amitriptyline, and monoamine oxidase inhibitors) can increase both the efficacy and toxicity of the drugs.
  • L-Tryptophan has been reported to compete with other large amino acids (such as phenylalanine, tyrosine, methionine, leucine, isoleucine, and valine) for transport across the blood-brain barrier, and possibly for absorption in the gastrointestinal tract.


  1. 1.0 1.1 1.2 Gaby, Alan R. (2011)Nutritional Medicine, Fritz Perlberg Publishing, Concord, NH
  2. 2.0 2.1 2.2 2.3 2.4 5-HTP Monograph: Natural Medicines Comprehensive Database, Retrieved February 10, 2014, from http://ezproxy.ccnm.edu:2076/nd/Search.aspx?cs=&s=ND&pt=100&id=794&ds=&name=5+HTP+(5-HTP)&searchid=45087484
  3. Trouillas, P., Brudon, F., Adeleine, P. (1988)Improvement of cerebellar ataxia with levorotatory form of 5-hydroxytryptophan. A double-blind study with quantified data-processing,Archives of Neurology;45(11):1217-122
  4. Birdsall, TC(1998)5-hydroxytryptophan: a clinically-effective serotonin precursor,Alternative Medicine Review: A Journal of Clinical Therapeutic;3(4):271-280
  5. Nicolodi, M., and Sicuteri, F.(1999)L-5-hydroxytryptophan can prevent nociceptive disorders in man,Advances in Experimental Medicine and Biology;467:177-82
  6. Bruni, O., Ferri, R., Miano, S.,Verrillo, E.(2004)L-5-hydroxytryptophan treatment of sleep terrors in children,European Journal of Pediatrics;163(7):402-407