The Who, What, Where, When and Sometimes, Why.


5- htp  

Natural Standard Monograph, Copyright © 2014 ( Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.

Related Terms

  • 5-Hydroxytroptophan, Griffonia plant seed extract, Griffonia simplicifolia, L-5-HTP, L-5-hydroxytroptophan, Natrol® 5-HTP, Natural Factors® 5-HTP, oxitriptan, serotonin, Tript-OH®, tryptophan.
  • Select combination products: Gabadone™ (5-HTP, tryptophan, and other amino acids), Nature’s Way 5-HTP (5-HTP, vitamin B6, vitamin C), Natural Factors® Tranquil Sleep (5-HTP, melatonin, L-theanine).
  • Note: 5-HTP should not to be confused with L-tryptophan.


  • 5-HTP is the precursor of the neurotransmitter serotonin. Commercially available 5-HTP is obtained from the seeds of the plant Griffonia simplicifolia.
  • 5-HTP has been suggested as a treatment for many conditions. Some research supports the use of 5-HTP in treating cerebellar ataxia, headache, depression, psychiatric disorders, and fibromyalgia, and as an appetite suppressant or weight loss agent. There is insufficient scientific evidence to support the use of 5-HTP for any other medical condition.
  • 5-HTP may cause gastrointestinal disturbances, mood disturbances, seizure, or abnormal blood counts. Some side effects might result from contaminants in 5-HTP products.


Uses based on scientific evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.


Cerebellar ataxia

5-HTP has been observed to have benefits in some people who have difficulty standing or walking because of cerebellar ataxia. However, current evidence is mixed.



Studies suggest that 5-HTP may reduce eating behaviors, lessen caloric intake, and promote weight loss in obese individuals.


Alcoholism (withdrawal symptoms)

Early research suggests that 5-HTP may lessen alcohol withdrawal symptoms. Further research is needed before a conclusion can be made.



Although 5-HTP has been proposed as a possible treatment for anxiety disorders, sufficient human evidence to make a firm conclusion is lacking.



The results of numerous studies in humans suggest that 5-HTP may aid in the treatment of depression. However, it is not known whether 5-HTP is as effective as commonly prescribed antidepressant drugs.


Down’s syndrome

Preliminary research on 5-HTP in children with Down’s syndrome has yielded insignificant results. Further research is necessary.



There is a small amount of research evaluating the use of 5-HTP for fibromyalgia. Early evidence suggests that 5-HTP may reduce the number of tender points, anxiety, and the intensity of pain, and may improve sleep, fatigue, and morning stiffness. Further research is needed before a conclusion can be made.



Several studies, in both children and adults, suggest that 5-HTP may be effective in reducing the severity and frequency of headaches, including tension headaches and migraines. Further research is needed.



In early research, 5-HTP lacked an effect on mood in healthy, young subjects. However, in this population, 5-HTP may impair decision-making. Further well-designed research is needed.


Neurologic disorders

5-HTP has been studied in panic disorder and various neurologic disorders. Additional clinical research is needed before conclusions can be made.


Parkinson’s disease

Parkinson’s disease is a neurological disorder that usually develops around the age of 50. The disorder occurs when the brain cells that make dopamine slowly degenerate. Symptoms include tremors (shaking) and difficulties with movement and coordination. 5-HTP has been studied, usually in combination with drugs, for Parkinson’s disease.


Psychiatric disorders

It has been suggested that 5-HTP may reduce psychotic symptoms and mania in panic disorder, but studies in people with schizophrenia have shown mixed results.


Sleep disorders

Insufficient evidence is currently available regarding the use of 5-HTP for sleep disorders. Additional studies are needed before a conclusion can be drawn.


Hot flashes

Limited research suggests that 5-HTP may be ineffective for reducing hot flash frequency in postmenopausal women. Further research is required before firm conclusions can be drawn.


Seizures/epilepsy (myoclonic disorders)

Although 5-HTP has been studied as a treatment for various myoclonic syndromes and epilepsy, available research does not support the use of 5-HTP for these conditions.


*Key to grades:

A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use (it may not work);
F: Strong scientific evidence against this use (it likely does not work).

For full grading rationale, click here.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional

Aggression, agoraphobia, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), anorexia, antioxidant, appetite suppressant, attention-deficit hyperactivity disorder (ADHD), autism, bulimia nervosa, cough, deficiency (aromatic L-amino acid decarboxylase deficiency, serotonin deficiency), delirium tremens (DTs), diabetes, digestion, dizziness, dystonia (muscle contraction disorder), eating disorders (binge eating), endocrine disorders (Cushing’s syndrome, hypothalamic syndrome), eye disorders (ophthalmoplegia), gastroesophageal reflux disease (GERD), gynecological disorders (premenstrual dysphoria), hepatitis, herpes virus infection (Ramsay Hunt syndrome), hormonal disorders, inflammation, melatonin deficiency, migraines, mood disorder, myoclonic disorders (Lance-Adams syndrome), pain, phenylketonuria, premenstrual syndrome, psychosis (LSD-induced), relaxation, restless leg syndrome, seasonal affective disorder, sexual dysfunction, stress, temperature regulation.


The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.


  • Avoid in individuals with a known allergy or hypersensitivity to 5-HTP. Signs of allergy may include rash, itching, or shortness of breath.

Side Effects and Warnings

  • In light of the concern related to eosinophilia myalgia syndrome (EMS), use of 5-HTP should be supervised by a qualified healthcare provider.
  • 5-HTP may cause abdominal pain, absence of menstrual bleeding, agitation, aggressiveness, anorexia, anxiety, depressed mood, diarrhea, dizziness, drowsiness, ear buzzing, eosinophilia, eosinophilia myalgia syndrome (EMS), euphoria, fatigue, gas, gastrointestinal side effects, hand wringing, headache, heartburn, hives, hypomania, impaired decision-making, increased appetite, increased blood cortisol or kynurenine, irritability, loss of inhibition, lowered blood pressure, lowered cholesterol, mania, muscle pain or weakness or breakdown, nausea, pacing, palpitations, psychic hyperkinetic syndrome, rapid speech, restlessness, seizure, scleroderma-like symptoms, sleep changes, slowed heart rate, sodium retention, strong muscle contractions, sweating, taste changes, vertigo, vivid dreams, vomiting, or weight gain.
  • Use cautiously in patients with existing gastrointestinal disorders, as 5-HTP may cause worsening of symptoms.
  • Use cautiously in patients with schizophrenia, due to the potential for worsening symptoms.
  • Use cautiously in patients with HIV/AIDS, particularly HIV-1 infection.
  • Use cautiously in patients with seizure disorders or those using agents that may lower the seizure threshold, due to increased risk of seizures.
  • Use cautiously in patients with a history of mental disorders.
  • Use cautiously in patients using CNS depressants. Drowsiness or sedation may occur. Use caution if driving or operating heavy machinery.
  • Use cautiously in patients taking decarboxylase inhibitors.
  • 5-HTP may cause low blood pressure. Caution is advised in patients taking drugs, herbs, or supplements that lower blood pressure.
  • Use cautiously in patients with bradycardia (slow heart rate).
  • Avoid in patients with eosinophilia syndromes, due to cases of eosinophilia and eosinophilia-myalgia syndrome (EMS).
  • Avoid in infants with Down syndrome, due to the potential for spasm.
  • Avoid in patients with mitochondrial encephalomyopathy.
  • Avoid in patients with suicidal thoughts, based on suicide attempts following 5-HTP use.
  • Avoid use in individuals using “party pills” (benzylpiperazine and trifluoromethylphenylpiperazine), based on population studies suggesting that the combination is associated with increased adverse effects from the party pills.
  • Avoid in patients taking antidepressant medications (tricyclics [TCAs], monoamine oxidase inhibitors [MAOIs], selective serotonin reuptake inhibitors [SSRIs], nefazodone, trazodone, venlafaxine, mirtazapine, or bupropion) or any other medications that may affect serotonin, due to potential increases in serotonin levels and increased risk of serotonin toxicity syndrome.
  • Avoid in women who are pregnant or lactating, due to a lack of safety data.
  • Avoid in patients with a known allergy to 5-HTP-containing products. Signs of allergy to 5-HTP may include rash, itching, or shortness of breath.

Pregnancy and Breastfeeding

  • Avoid in pregnant or breastfeeding women, due to a lack of available scientific evidence. 5-HTP products may contain contaminants or increase levels of prolactin, a hormone needed for milk production.


Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.

Interactions with Drugs

  • Note: 5-HTP is a precursor to serotonin; thus, it may interact with agents that modulate levels of serotonin.
  • 5-HTP may cause low blood pressure. Caution is advised in patients taking drugs that lower blood pressure.
  • 5-HTP may interfere with the way the body processes certain drugs using the liver’s cytochrome P450 enzyme system. As a result, the levels of these drugs may be increased or decreased in the blood, and may cause increased or decreased effects or potentially serious adverse reactions. Patients using any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
  • 5-HTP may increase the amount of drowsiness caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, and alcohol. Caution is advised while driving or operating machinery.
  • 5-HTP may interact with angiotensin-converting enzyme receptor blockers (ARBs), antianxiety agents (such as buspirone and trazodone), anticancer agents, antidepressants (including monoamine oxidase inhibitors [MAOIs] such as L-deprenyl, selective serotonin reuptake inhibitors [SSRIs], serotonin and norepinephrine reuptake inhibitors [SNRIs] such as venlafaxine, tetracyclics such as mirtazapine, or tricyclics [TCAs]), anti-inflammatories, antiobesity agents (such as phentermine), antiseizure agents, antipsychotic agents (such as haloperidol), barbiturates (such as pentobarbital), benzodiazepines, benzylpiperazine, cannabinoids (such as tetrahydrocannabinol), cholesterol-lowering agents, CNS depressants, decarboxylase inhibitors (such as carbidopa and benserazide), diltiazem, drugs that lower seizure threshold, growth hormones, hormonal agents, lithium carbonate, losartan, methamphetamine, metoclopramide, painkillers, sedatives, serotonin receptor antagonists (such as methysergide, nefazodone, cyproheptadine, and ritanserin), or thyroid hormones.

Interactions with Herbs and Dietary Supplements

  • 5-HTP may cause low blood pressure. Caution is advised in patients taking herbs or supplements that lower blood pressure.
  • 5-HTP may interfere with the way the body processes certain herbs or supplements using the liver’s cytochrome P450 enzyme system. As a result, the levels of other herbs or supplements may become too high or too low in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
  • 5-HTP may increase the amount of drowsiness caused by some herbs or supplements.
  • 5-HTP may interact with Alpinia zerumbet, antianxiety agents (such as St. John’s wort), anticancer agents, antidepressants (including monoamine oxidase inhibitors [MAOIs] and selective serotonin reuptake inhibitors [SSRIs]), anti-inflammatories, antiobesity agents, antioxidants, antiseizure agents, antipsychotics, cannabinoids, cholesterol-lowering agents, chromium, herbs that lower the seizure threshold, hormonal herbs and supplements, jujubosides from Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H.F.Chow, L-tyrosine, magnesium, melatonin, niacin, painkillers, protein, SAMe, sedatives, serotonin receptor antagonists, spinosin, theanine, thyroid herbs and supplements, tryptophan, tryptophan-containing foods, or vitamin B6.


  • This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

Selected References

Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to Selected references are listed below.

  1. Bagdy G, Kecskemeti V, Riba P, et al. Serotonin and epilepsy. J Neurochem 2007;100(4):857-873.
  2. 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(6):357-365.
  3. Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev 1998;3(4):271-280.
  4. Bono G, Micieli G, Sances G, et al. L-5HTP treatment in primary headaches: an attempt at clinical identification of responsive patients. Cephalalgia 1984;4(3):159-165.
  5. Caruso I, Sarzi Puttini P, Cazzola M, et al. Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. J Int Med Res 1990;18(3):201-209.
  6. Chae HS, Kang OH, Choi JG, et al. Y. 5-hydroxytryptophan acts on the mitogen-activated protein kinase extracellular-signal regulated protein kinase pathway to modulate cyclooxygenase-2 and inducible nitric oxide synthase expression in RAW 264.7 cells. Biol Pharm Bull 2009;32(4):553-557.
  7. De Giorgis G, Miletto R, Iannuccelli M, et al. Headache in association with sleep disorders in children: a psychodiagnostic evaluation and controlled clinical study–L-5-HTP versus placebo. Drugs Exp Clin Res 1987;13(7):425-433.
  8. Eriksson O, Wall A, Marteinsdottir I, et al. Mood changes correlate to changes in brain serotonin precursor trapping in women with premenstrual dysphoria. Psychiatry Res 2006;146(2):107-116.
  9. Gendle MH, Golding AC. Oral administration of 5-hydroxytryptophan (5-HTP) impairs decision making under ambiguity but not under risk: evidence from the Iowa Gambling Task. Hum Psychopharmacol 2010;25(6):491-499.
  10. Halford JC, Harrold JA, Boyland EJ, et al. Serotonergic drugs: effects on appetite expression and use for the treatment of obesity. Drugs 2007;67(1):27-55.
  11. Loftis JM, Turner EH. Novel treatment strategies for depression in patients with hepatitis C. Psychosomatics 2010;51(4):357-358.
  12. Ohno Y, Imaki J, Mae Y, et al. Serotonergic modulation of extrapyramidal motor disorders in mice and rats: role of striatal 5-HT(3) and 5-HT(6) receptors. Neuropharmacology 2011;60(2-3):201-208
  13. Schott DA, Nicolai J, de Vries JE, et al. Disorder in the serotonergic system due to tryptophan hydroxylation impairment: a cause of hypothalamic syndrome? Horm Res Paediatr 2010;73(1):68-73.
  14. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;(1):CD003198.
  15. Titus F, Davalos A, Alom J, et al. 5-Hydroxytryptophan versus methysergide in the prophylaxis of migraine. Randomized clinical trial. Eur Neurol 1986;25(5):327-329.


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