What is it?
People use L-tryptophan for severe PMS symptoms (premenstrual dysphoric disorder or PMDD), athletic performance, depression, insomnia, and many other conditions, but there is no good scientific evidence to support these uses.
How effective is it?
Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.
The effectiveness ratings for L-TRYPTOPHAN are as follows:
Possibly ineffective for...
- Teeth grinding (bruxism). Taking L-tryptophan by mouth doesn't help treat teeth grinding.
- A condition that causes persistent muscle pain (myofascial pain syndrome). Taking L-tryptophan by mouth doesn't help reduce this type of pain.
Insufficient evidence to rate effectiveness for...
- Athletic performance. Some research shows that taking L-tryptophan for 3 days before exercising can improve power during exercise. This improvement in power helps increase the distance an athlete can go in the same amount of time. But other early research shows that taking L-tryptophan during exercise doesn't improve endurance during a cycling exercise. Reasons for the conflicting results are not clear. It is possible that L-tryptophan improves some measures of athletic ability but not others. On the other hand, L-tryptophan might need to be taken for a few days before exercise in order to see any benefit.
- Attention deficit-hyperactivity disorder (ADHD). There is some evidence that L-tryptophan levels are lower in children with ADHD. But taking L-tryptophan supplements does not appear to improve ADHD symptoms.
- Depression. Early research suggests that L-tryptophan might improve the effectiveness of common medications for depression.
- Fibromyalgia. Early research shows that adding walnuts to a Mediterranean diet to provide extra L-tryptophan and magnesium might improve anxiety and some other symptoms of fibromyalgia.
- A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Research shows that taking L-tryptophan in combination with the ulcer medication omeprazole improves ulcer healing rates compared to taking omeprazole alone.
- Insomnia. Taking L-tryptophan might decrease the amount of time it takes to fall asleep and improve mood in healthy people with sleep problems. Taking L-tryptophan might also improve sleep in people with sleep problems related to withdrawal of illegal drugs.
- Migraine. Early research has found that having low levels of L-tryptophan in the diet is linked to an increased risk of migraine.
- Severe PMS symptoms (premenstrual dysphoric disorder or PMDD). Taking 6 grams of L-tryptophan per day seems to decrease mood swings, tension, and irritability in women with PMDD.
- Seasonal depression (seasonal affective disorder or SAD). Early research suggests L-tryptophan might be helpful in SAD.
- A sleep disorder in which people temporarily stop breathing while asleep (sleep apnea). There is some evidence that taking L-tryptophan might decrease episodes in some people with a certain form of this condition, called obstructive sleep apnea (OSA).
- Quitting smoking. Taking L-tryptophan along with conventional treatment might help some people to quit smoking.
- Decline in memory and thinking skills in older people that is more than what is normal for their age.
- Premenstrual syndrome (PMS).
- Tourette syndrome.
- Other conditions.
How does it work?
Are there safety concerns?
There isn't enough reliable information to know if L-tryptophan is safe when taken by mouth long-term.
Special precautions & warnings:Pregnancy and breast-feeding: L-tryptophan is LIKELY UNSAFE in pregnancy because it may harm the unborn child. There isn't enough reliable information to know if L-tryptophan is safe to use when breast-feeding. Stay on the safe side and avoid L-tryptophan during pregnancy and breast-feeding.
Are there interactions with medications?
- Sedative medications (CNS depressants)
- L-tryptophan might cause sleepiness and drowsiness. Medications that cause sleepiness are called sedatives. Taking L-tryptophan along with sedative medications might cause too much sleepiness.
Some sedative medications include clonazepam (Klonopin), lorazepam (Ativan), phenobarbital (Donnatal), zolpidem (Ambien), and others.
- Serotonergic drugs
- L-tryptophan increases a chemical in the brain called serotonin. Some medications also increase serotonin. Taking L-tryptophan along with these medications might increase serotonin too much. This can cause serious side effects including severe headache, heart problems, shivering, confusion, and anxiety.
Some of these medications include fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Tofranil), sumatriptan (Imitrex), zolmitriptan (Zomig), rizatriptan (Maxalt), methadone (Dolophine), tramadol (Ultram), and many others.
Are there interactions with herbs and supplements?
- Herbs and supplements with sedative properties
- L-tryptophan can cause drowsiness and relaxation. Using it along with other herbs and supplements that also have sedative effects might cause too much drowsiness. Some of these herbs and supplements include 5-HTP, calamus, California poppy, catnip, hops, Jamaican dogwood, kava, St. John's wort, skullcap, valerian, yerba mansa, and others.
- Herbs and supplements with serotonergic properties
- L-tryptophan seems to raise the level of serotonin, a hormone that transmits signals between nerve cells and affects mood. There is a concern that using it with other herbs and supplements that increase serotonin, might increase the effects and side effects of those herbs and supplements. Some of those include 5-HTP, Hawaiian baby woodrose, and S-adenosylmethionine (SAMe).
- St. John's wort
- Combining L-tryptophan with St. John's wort might increase the risk of serotonin syndrome, a possibly fatal condition that occurs when there is too much serotonin in the body. There is a report of serotonin syndrome in a patient who took L-tryptophan and high doses of St. John's wort.
Are there interactions with foods?
- There are no known interactions with foods.
What dose is used?
The appropriate dose of L-tryptophan depends on several factors such as the user's age, health, and several other conditions. At this time there is not enough scientific information to determine an appropriate range of doses for L-tryptophan. Keep in mind that natural products are not always necessarily safe and dosages can be important. Be sure to follow relevant directions on product labels and consult your pharmacist or physician or other healthcare professional before using.
To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.
- Martínez-Rodríguez A, Rubio-Arias JÁ, Ramos-Campo DJ, Reche-García C, Leyva-Vela B, Nadal-Nicolás Y. Psychological and Sleep Effects of Tryptophan and Magnesium-Enriched Mediterranean Diet in Women with Fibromyalgia. Int J Environ Res Public Health. 2020;17:2227. View abstract.
- Razeghi Jahromi S, Togha M, Ghorbani Z, et al. The association between dietary tryptophan intake and migraine. Neurol Sci. 2019;40:2349-55. View abstract.
- Ullrich SS, Fitzgerald PCE, Giesbertz P, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of intragastric administration of tryptophan on the blood glucose response to a nutrient drink and energy intake, in lean and obese men. Nutrients 2018;10. pii: E463. View abstract.
- Oshima S, Shiiya S, Nakamura Y. Serum uric acid-lowering effects of combined glycine and tryptophan treatments in subjects with mild hyperuricemia: a randomized, double-blind, placebo-controlled, crossover study. Nutrients 2019;11. pii: E564. View abstract.
- Cynober L, Bier DM, Kadowaki M, Morris SM Jr, Elango R, Smriga M. Proposals for upper limits of safe intake for arginine and tryptophan in young adults and an upper limit of safe intake for leucine in the elderly. J Nutr 2016;146:2652S-2654S. View abstract.
- Wang D, Li W, Xiao Y, et al. Tryptophan for the sleeping disorder and mental symptom of new-type drug dependence: a randomized, double-blind, placebo-controlled trial. Medicine (Baltimore) 2016;95:e4135. View abstract.
- Sainio EL, Pulkki K, Young SN. L-tryptophan: biochemical, nutritional and pharmacological aspects. Amino Acids 1996;10:21-47. View abstract.
- Javierre C, Segura R, Ventura JL, Suárez A, Rosés JM. L-tryptophan supplementation can decrease fatigue perception during an aerobic exercise with supramaximal intercalated anaerobic bouts in young healthy men. Int J Neurosci. 2010 May;120:319-27. View abstract.
- Hiratsuka C, Sano M, Fukuwatari T, Shibata K. Time-dependent effects of L-tryptophan administration on urinary excretion of L-tryptophan metabolites. J Nutr Sci Vitaminol (Tokyo). 2014;60:255-60. View abstract.
- Hiratsuka C, Fukuwatari T, Sano M, Saito K, Sasaki S, Shibata K. Supplementing healthy women with up to 5.0 g/d of L-tryptophan has no adverse effects. J Nutr. 2013 Jun;143:859-66. View abstract.
- Rondanelli M, Opizzi A, Faliva M, et al. Effects of a diet integration with an oily emulsion of DHA-phospholipids containing melatonin and tryptophan in elderly patients suffering from mild cognitive impairment. Nutr.Neurosci 2012;15:46-54.View abstract.
- Celinski, K., Konturek, S. J., Konturek, P. C., Brzozowski, T., Cichoz-Lach, H., Slomka, M., Malgorzata, P., Bielanski, W., and Reiter, R. J. Melatonin or L-tryptophan accelerates healing of gastroduodenal ulcers in patients treated with omeprazole. J.Pineal Res. 2011;50:389-394. View abstract.
- Korner E, Bertha G, Flooh E, et al. Sleep-inducing effect of L-tryptophane. Eur Neurol 1986;25 Suppl 2:75-81. View abstract.
- Bryant SM, Kolodchak J. Serotonin syndrome resulting from an herbal detox cocktail. Am J Emerg Med 2004;22:625-6. View abstract.
- Carr L, Ruther E, Berg PA, Lehnert H. Eosinophilia-myalgia syndrome in Germany: an epidemiologic review. Mayo Clin Proc 1994;69:620-5. View abstract.
- Mayeno AN, Gleich GJ. The eosinophilia-myalgia syndrome: lessons from Germany. Mayo Clin Proc 1994;69:702-4. View abstract.
- Shapiro S. Epidemiologic studies of the association of L-tryptophan with the eosinophilia-myalgia syndrome: a critique. J Rheumatol Suppl 1996;46:44-58. View abstract.
- Horwitz RI, Daniels SR. Bias or biology: evaluating the epidemiologic studies of L-tryptophan and the eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:60-72. View abstract.
- Kilbourne EM, Philen RM, Kamb ML, Falk H. Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome. J Rheumatol Suppl 1996;46:81-8. View abstract.
- van Praag HM. Management of depression with serotonin precursors. Biol Psychiatry 1981;16:291-310.. View abstract.
- Walinder J, Skott A, Carlsson A, et al. Potentiation of the antidepressant action of clomipramine by tryptophan. Arch Gen Psychiatry 1976;33:1384-89.. View abstract.
- Murphy FC, Smith KA, Cowen PJ, et al. The effects of tryptophan depletion on cognitive and affective processing in healthy volunteers. Psychopharmacology (Berl) 2002;163:42-53.. View abstract.
- Bell C, Abrams J, Nutt D. Tryptophan depletion and its implications for psychiatry. Br J Psychiatry 2001;178:399-405.. View abstract.
- Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;:CD003198. View abstract.
- Simat TJ, Kleeberg KK, Muller B, Sierts A. Synthesis, formation, and occurrence of contaminants in biotechnologically manufactured L-tryptophan. Adv Exp Med Biol 1999;467:469-80.. View abstract.
- Klein R, Berg PA. A comparative study on antibodies to nucleoli and 5-hydroxytryptamine in patients with fibromyalgia syndrome and tryptophan-induced eosinophilia-myalgia syndrome. Clin Investig 1994;72:541-9.. View abstract.
- Priori R, Conti F, Luan FL, et al. Chronic fatigue: a peculiar evolution of eosinophilia myalgia syndrome following treatment with L-tryptophan in four Italian adolescents. Eur J Pediatr 1994;153:344-6.. View abstract.
- Greenberg AS, Takagi H, Hill RH, et al. Delayed onset of skin fibrosis after the ingestion of eosinophilia-myalgia syndrome-associated L-tryptophan. J Am Acad Dermatol 1996;35:264-6. View abstract.
- Ghose K. l-Tryptophan in hyperactive child syndrome associated with epilepsy: a controlled study. Neuropsychobiology 1983;10:111-4. View abstract.
- Bornstein RA, Baker GB, Carroll A, et al. Plasma amino acids in attention deficit disorder. Psychiatry Res 1990;33:301-6.. View abstract.
- Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. View abstract.
- Bohme A, Wolter M, Hoelzer D. L-tryptophan-related eosinophilia-myalgia syndrome possibly associated with a chronic B-lymphocytic leukemia. Ann Hematol 1998;77:235-8.
- Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. Am J Epidemiol 1993;138:154-9. View abstract.
- Sullivan EA, Kamb ML, Jones JL, et al. The natural history of eosinophilia-myalgia syndrome in a tryptophan-exposed cohort in South Carolina. Arch Intern Med 1996;156:973-9. View abstract.
- Hatch DL, Goldman LR. Reduced severity of eosinophilia-myalgia syndrome associated with consumption of vitamin-containing supplements before illness. Arch Intern Med 1993;153: 2368-73. View abstract.
- Shapiro S. L-tryptophan and eosinophilia-myalgia syndrome. Lancet 1994;344:817-9.View abstract.
- Hudson JI, Pope HG, Daniels SR, Horwitz RI. Eosinophilia-myalgia syndrome or fibromyalgia with eosinophilia? JAMA 1993;269:3108-9. View abstract.
- U. S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements. Information Paper on L-Tryptophan and 5-hydroxy-L-tryptophan, February 2001.
- Ghadirian AM, Murphy BE, Gendron MJ. Efficacy of light versus tryptophan therapy in seasonal affective disorder. J Affect Disord 1998;50:23-7. View abstract.
- Steinberg S, Annable L, Young SN, Liyanage N. A placebo-controlled study of the effects of L-tryptophan in patients with premenstrual dysphoria. Adv Exp Med Biol 1999;467:85-8. View abstract.
- Nardini M, De Stefano R, Iannuccelli M, et al. Treatment of depression with L-5-hydroxytryptophan combined with chlorimipramine, a double-blind study. Int J Clin Pharmacol Res 1983;3:239-50. View abstract.
- Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline . Washington, DC: National Academy Press, 2000. Available at: http://books.nap.edu/books/0309065542/html/.
- Hartmann E, Spinweber CL. Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake. J Nerv Ment Dis 1979;167:497-9. View abstract.
- Seltzer S, Dewart D, Pollack R, Jackson E. The effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance. J Psychiatr Res 1982-83;17:181-6. View abstract.
- Schmidt HS. L-tryptophan in the treatment of impaired respiration in sleep. Bull Eur Physiopathol Respir 1983;19:625-9. View abstract.
- Lieberman HR, Corkin S, Spring BJ. The effects of dietary neurotransmitter precursors on human behavior. Am J Clin Nutr 1985;42:366-70. View abstract.
- Devoe LD, Castillo RA, Searle NS. Maternal dietary substrates and human fetal biophysical activity. The effects of tryptophan and glucose on fetal breathing movements. Am J Obstet Gynecol 1986;155:135-9. View abstract.
- Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. View abstract.
- Stockstill JW, McCall D Jr., Gross AJ. The effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain. J Am Dent Assoc 1989;118:457-60. View abstract.
- Etzel KR, Stockstill JW, Rugh JD. Tryptophan supplementation for nocturnal bruxism: report of negative results. J Craniomandib Disord 1991;5:115-20. View abstract.
- Bowen DJ, Spring B, Fox E. Tryptophan and high-carbohydrate diets as adjuncts to smoking cessation therapy. J Behav Med 1991;14:97-110. View abstract.
- Delgado PL, Price LH, Miller HL. Serotonin and the neurobiology of depression. Effects of tryptophan depletion in drug-free depressed patients. Arch Gen Psychiatr 1994;51:865-74. View abstract.
- van Hall G, Raaymakers JS, Saris WH. Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performance. J Physiol (Lond) 1995;486:789-94. View abstract.
- Sharma RP, Shapiro LE, Kamath SK. Acute dietary tryptophan depletion: effects on schizophrenic positive and negative symptoms. Neuropsychobiol 1997;35:5-10. View abstract.
- Smith KA, Fairburn CG, Cowen PJ. Symptomatic relapse in bulimia nervosa following acute tryptophan depletion. Arch Gen Psychiatr 1999;56:171-6. View abstract.
- Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.