L-Triptofano, L-Trypt, L-2-amino-3-(indole-3-yl) propionic acid, L-Tryptophane, Tryptophan.<br/><br/>
Overview InformationL-tryptophan is an amino acid. Amino acids are protein building blocks. L-tryptophan is called an "essential" amino acid because the body can't make it. It must be acquired from food.
People use L-tryptophan for some mental health disorders, to help quit smoking, for athletic performance, and for emotional symptoms in people with premenstrual dysphoric disorder (PMDD), but there is no good scientific evidence to support many of these uses. There is also concern that using L-tryptophan might cause a condition called eosinophilia-myalgia syndrome (EMS).
How does it work?L-tryptophan is naturally found in animal and plant proteins. L-tryptophan is considered an essential amino acid because our bodies can't make it. It is important for the development and functioning of many organs in the body. After absorbing L-tryptophan from food, our bodies convert it to 5-HTP (5-hyrdoxytryptophan), and then to serotonin, melatonin, and vitamin B6 (nicotinamide). Serotonin is a hormone that transmits signals between nerve cells. It also causes blood vessels to narrow. Changes in the level of serotonin in the brain can alter mood. Melatonin is important for sleep and vitamin B6 is essential for energy metabolism.
Uses & Effectiveness
Possibly Effective for
- Premenstrual dysphoric disorder (PMDD). Taking 6 grams of L-tryptophan per day seems to decrease mood swings, tension, and irritability in women with PMDD.
- To help people quit smoking. Taking L-tryptophan seems to help people quit smoking when used with conventional treatment.
Possibly Ineffective for
- Teeth grinding (bruxism). Taking L-tryptophan by mouth doesn't help treat teeth grinding.
- Facial pain. Taking L-tryptophan by mouth doesn't help reduce facial pain.
Insufficient Evidence for
- Improving athletic ability. 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.
- Problems with mental function in the elderly. Taking a mixture of L-tryptophan and other ingredients can slightly improve mental function in older people. But the improvement is very small, so it might not be meaningful. Also, it's not known if any potential benefit is due to L-tryptophan or another ingredient.
- Depression. Early research suggests that L-tryptophan might improve the effectiveness of common medications for depression.
- Healing ulcers caused by the bacteria Helicobacter pylori (H pylori). Research shows that taking L-tryptophan in combination with the ulcer medication omeprazole improves ulcer healing rates compared to taking omeprazole alone.
- Treating sleep disorders. 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.
- Seasonal affective disorder (SAD). Early research suggests L-tryptophan might be helpful in SAD.
- Treating sleep apnea. There is some evidence that taking L-tryptophan might decrease episodes in some people who periodically stop breathing during sleep (sleep apnea).
- Other conditions.
Side Effects & SafetyL-tryptophan is POSSIBLY UNSAFE when taken by mouth as a medicine. It has been linked to over 1500 reports of eosinophilia-myalgia syndrome (EMS) and 37 deaths. EMS is a neurological condition with symptoms that include fatigue; intense muscle pain; nerve pain; skin changes; baldness; rash; and pain and swelling affecting the joints, connective tissue, lungs, heart, and liver. Symptoms tend to improve over time, but some people may still experience symptoms up to 2 years after they develop EMS. Some people report that their symptoms have never gone away completely.
In 1990, L-tryptophan was recalled from the market due to these safety concerns. After the limitation of L-tryptophan products, the number of EMS cases dropped sharply. The exact cause of EMS in patients taking L-tryptophan is unknown, but some evidence suggests it may be due to contaminated L-tryptophan products. About 95% of all EMS cases were traced to L-tryptophan produced by a single manufacturer in Japan. Currently, under the Dietary Supplement Health and Education Act (DSHEA) of 1994, L-tryptophan is available and marketed as a dietary supplement.
L-tryptophan can cause some side effects such as heartburn, stomach pain, belching and gas, nausea, vomiting, diarrhea, and loss of appetite. It can also cause headache, lightheadedness, drowsiness, dry mouth, visual blurring, muscle weakness, and sexual problems.
Special Precautions & Warnings:Pregnancy and breast-feeding: L-tryptophan is LIKELY UNSAFE in pregnancy because it may harm the unborn child. Not enough is known about the safety of L-tryptophan during breast-feeding. Avoid using L-tryptophan during pregnancy and breast-feeding.
A white blood cell disorder called eosinophilia: L-tryptophan might make this condition worse. L-tryptophan has been associated with the development of eosinophilia-myalgia syndrome (EMS).
Liver or kidney disease: L-tryptophan might make these conditions worse since it has been associated with the development of eosinophilia-myalgia syndrome (EMS).
Do not take this combination
Medications for depression (Antidepressant drugs) interacts with L-TRYPTOPHAN
L-tryptophan increases a brain chemical called serotonin. Some medications for depression also increase the brain chemical serotonin. Taking L-tryptophan along with these medications for depression might increase serotonin too much and cause serious side effects including heart problems, shivering, and anxiety. Do not take L-tryptophan if you are taking medications for depression.<br/><br/> Some of these medications for depression include fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), amitriptyline (Elavil), clomipramine (Anafranil), imipramine (Tofranil), and others.
Medications for depression (MAOIs) interacts with L-TRYPTOPHAN
L-tryptophan increases a chemical in the brain. This chemical is called serotonin. Some medications used for depression also increase serotonin. Taking L-tryptophan with these medications used for depression might cause there to be too much serotonin. This could cause serious side effects including heart problems, shivering, and anxiety.<br/><br/> Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.
Sedative medications (CNS depressants) interacts with L-TRYPTOPHAN
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.<br/><br/> Some sedative medications include clonazepam (Klonopin), lorazepam (Ativan), phenobarbital (Donnatal), zolpidem (Ambien), and others.
Be cautious with this combination
Dextromethorphan (Robitussin DM, and others) interacts with L-TRYPTOPHAN
L-Tryptophan can affect a brain chemical called serotonin. Dextromethorphan (Robitussin DM, others) can also affect serotonin. Taking L-tryptophan along with dextromethorphan (Robitussin DM, others), might cause there to be too much serotonin in the brain and serious side effects including heart problems, shivering and anxiety could occur. Do not take L-tryptophan if you are taking dextromethorphan (Robitussin DM, others).
Meperidine (Demerol) interacts with L-TRYPTOPHAN
L-tryptophan increases a chemical in the brain called serotonin. Meperidine (Demerol) can also increase serotonin in the brain. Taking L-tryptophan along with meperidine (Demerol) might cause too much serotonin in the brain and serious side effects including heart problems, shivering, and anxiety.
Pentazocine (Talwin) interacts with L-TRYPTOPHAN
L-tryptophan increases a brain chemical called serotonin. Pentazocine (Talwin) also increases serotonin. Taking L-tryptophan along with pentazocine (Talwin) might cause serious side effects including heart problems, shivering, and anxiety. Do not take L-tryptophan if you are taking pentazocine (Talwin).
Phenothiazines interacts with L-TRYPTOPHAN
Taking L-tryptophan with phenothiazines can cause serious side effects including movement disorders.<br/><br/> Some phenothiazines include chlorpromazine (Thorazine), fluphenazine (Prolixin), trifluoperazine (Stelazine), thioridazine (Mellaril), and others.
Sedative medications (Benzodiazepines) interacts with L-TRYPTOPHAN
Sedative medications can affect the nervous system. L-tryptophan can also affect the nervous system. Taking L-tryptophan along with sedative medications can cause serious side effects. Do not take L-tryptophan if you are taking sedative medications.<br/><br/> Some of these sedative medications include clonazepam (Klonopin), diazepam (Valium), lorazepam (Ativan), and others.
Tramadol (Ultram) interacts with L-TRYPTOPHAN
Tramadol (Ultram) can affect a chemical in the brain called serotonin. L-tryptophan can also affect serotonin. Taking L-tryptophan along with tramadol (Ultram) might cause too much serotonin in the brain and side effects including confusion, shivering, and stiff muscles could result.
The following doses have been studied in scientific research:
- Premenstrual dysphoric disorder (PMDD): Doses of 6 grams of L-tryptophan have been taken daily from ovulation to the third day of the period.
- To help people quit smoking: Doses of 50 mg/kg of L-tryptophan have been taken daily.
- Saito YA, Rey E, Almazar-Elder AE, et al. A randomized, double-blind, placebo-controlled trial of St. John's wort for treating irritable bowel syndrome. Am J Gastroenterol 2010;105:170-7. View abstract.
- Samadi S, Khadivzadeh T, Emami A, et al. The effect of Hypericum perforatum on the wound healing and scar of cesarean. J Altern Complement Med 2010;16:113-7. View abstract.
- Schempp C, Pelz K, Wittmer A, et al. Antibacterial activity of hyperforin from St. John's wort, against multiresistant Stapylococcus aureus and gram-positive bacteria. Lancet 1999;353:2129. View abstract.
- Schempp CM, Kirkin V, Simon-Haarhaus B, et al. Inhibition of tumour cell growth by hyperforin, a novel anticancer drug from St. John's wort that acts by induction of apoptosis. Oncogene 2002;21:1242-50.. View abstract.
- Schempp CM, Ludtke R, Winghofer B, Simon JC. Effect of topical application of hypericum perforatum extract on skin sensitivity to solar simulated radiation. Photodermatol Photoimmunol Photomed 2000;16:125-8. View abstract.
- Niederhofer H. St. John's wort may improve some symptoms of attention-deficit hyperactivity disorder. Nat Prod Res 2010;24(3):203-5. View abstract.
- Nierenberg AA, Burt T, Matthews J, et al. Mania associated with St. John's wort. Biol Psychiatry 1999;46:1707-8. View abstract.
- O'Breasail AM, Argouarch S. Hypomania and St John's wort. Can J Psychiatry 1998;43:746-7. View abstract.
- Obach RS. Inhibition of human cytochrome P450 enzymes by constituents of St. John's wort, an herbal preparation used in the treatment of depression. J Pharmacol Exp Ther 2000;294:88-95. View abstract.
- Ondrizek RR, Chan PJ, Patton WC, King A. An alternative medicine study of herbal effects on the penetration of zona-free hamster oocytes and the integrity of sperm deoxyribonucleic acid. Fertil Steril 1999;71:517-22. View abstract.
- Ondrizek RR, Chan PJ, Patton WC, King A. Inhibition of human sperm motility by specific herbs used in alternative medicine. J Assist Reprod Genet 1999;16:87-91. View abstract.
- Pakseresht S, Boustani H, Azemi ME, et al. Evaluation of pharmaceutical products of St. John's wort efficacy added on tricyclic antidepressants in treating major depressive disorder: a double blind randomized control trial. Jundishapur J Nat Pharm Prod 2012;7(3):106-10. View abstract.
- Parker V, Wong AH, Boon HS, Seeman MV. Adverse reactions to St John's Wort. Can J Psychiatry 2001;46:77-9. View abstract.
- Patel S, Robinson R, Burk M. Hypertensive crisis associated with St. John's Wort. Am J Med 2002;112:507-8. View abstract.
- Patel, J., Buddha, B., Dey, S., Pal, D., and Mitra, A. K. In vitro interaction of the HIV protease inhibitor ritonavir with herbal constituents: changes in P-gp and CYP3A4 activity. Am.J.Ther. 2004;11(4):262-277. View abstract.
- Peebles, K. A., Baker, R. K., Kurz, E. U., Schneider, B. J., and Kroll, D. J. Catalytic inhibition of human DNA topoisomerase II alpha by hypericin, a naphthodianthrone from St. John's wort (Hypericum perforatum). Biochem Pharmacol 10-15-2001;62(8):1059-1070. View abstract.
- Peirce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York, NY: William Morrow and Co., 1999.
- Peltoniemi MA, Saari TI, Hagelberg NM, et al. St John's wort greatly decreases the plasma concentrations of oral S-ketamine. Fundam Clin Pharmacol 2012;26(6):743-50. View abstract.
- Pfrunder A, Schiesser M, Gerber S, et al. Interaction of St John's wort with low-dose oral contraceptive therapy: a randomized controlled trial. Br J Clin Pharmacol 2003;56:683-90. View abstract.
- Philipp M, Kohnen R, Hiller KO. Hypericum extract versus imipramine or placebo in patients with moderate depression: randomized multicentre study of treatment for eight weeks. BMJ 1999;319:1534-9. View abstract.
- Piscitelli SC, Burstein AH, Chaitt D, et al. Indinavir concentrations and St John's wort. Lancet 2000;355:547-8. View abstract.
- Raak C, Büssing A, Gassmann G, et al. A systematic review and meta-analysis on the use of Hypericum perforatum (St. John's wort) for pain conditions in dental practice. Homeopathy 2012;101(4):204-10. View abstract.
- Rayburn WF, Gonzalez CL, Christensen HD, Stewart JD. Effect of prenatally administered hypericum (St John's wort) on growth and physical maturation of mouse offspring. Am J Obstet Gynecol 2001;184:191-5. View abstract.
- Rengelshausen, J., Banfield, M., Riedel, K. D., Burhenne, J., Weiss, J., Thomsen, T., Walter-Sack, I., Haefeli, W. E., and Mikus, G. Opposite effects of short-term and long-term St John's wort intake on voriconazole pharmacokinetics. Clin.Pharmacol Ther. 2005;78(1):25-33. View abstract.
- Rey JM, Walter G. Hypericum perforatum (St. John's wort) in depression: pest or blessing? Med J Aust 1998;169:583-6. View abstract.
- Richter O. Several countries issue restrictions on St. John's wort. Richter's HerbLetter 7/30/00. Available at: www.richters.com (Accessed 01 March 2002).
- Roberts JE, Wang RH, Tan IP, et al. Hypericin (active ingredient in St. John's wort) photo-oxidation of lens proteins. Photochem Photobiol 1999;69:42S.
- Roby CA, Anderson GD, Kantor E, et al. St. John's wort: Effect on CYP3A4 activity. Clin Pharmacol Ther 2000;67:451-7. 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(4):389-394. View abstract.
- Bell C, Abrams J, Nutt D. Tryptophan depletion and its implications for psychiatry. Br J Psychiatry 2001;178:399-405.. 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.
- Bornstein RA, Baker GB, Carroll A, et al. Plasma amino acids in attention deficit disorder. Psychiatry Res 1990;33:301-6.. 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.
- 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.
- 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(12):2652S-2654S. 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.
- 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.
- Etzel KR, Stockstill JW, Rugh JD. Tryptophan supplementation for nocturnal bruxism: report of negative results. J Craniomandib Disord 1991;5:115-20. View abstract.
- 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.
- Ghose K. l-Tryptophan in hyperactive child syndrome associated with epilepsy: a controlled study. Neuropsychobiology 1983;10:111-4. 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.
- 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.
- 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.
- 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(6):859-66. 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(4):255-60. 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.
- Hudson JI, Pope HG, Daniels SR, Horwitz RI. Eosinophilia-myalgia syndrome or fibromyalgia with eosinophilia? JAMA 1993;269:3108-9. 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(5):319-27. 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.
- 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.
- Korner E, Bertha G, Flooh E, et al. Sleep-inducing effect of L-tryptophane. Eur Neurol 1986;25 Suppl 2:75-81. 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.
- Mayeno AN, Gleich GJ. The eosinophilia-myalgia syndrome: lessons from Germany. Mayo Clin Proc 1994;69:702-4. View abstract.
- Messiha FS. Fluoxetine: adverse effects and drug-drug interactions. J Toxicol Clin Toxicol 1993;31:603-30. 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.
- 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.
- Philen RM, Hill RH, Flanders WD, et al. Tryptophan contaminants associated with eosinophilia-myalgia syndrome. Am J Epidemiol 1993;138:154-9. 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.
- 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(2):46-54.View abstract.
- Sainio EL, Pulkki K, Young SN. L-tryptophan: biochemical, nutritional and pharmacological aspects. Amino Acids 1996;10(1):21-47. View abstract.
- Schmidt HS. L-tryptophan in the treatment of impaired respiration in sleep. Bull Eur Physiopathol Respir 1983;19:625-9. 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.
- 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.
- Shapiro S. L-tryptophan and eosinophilia-myalgia syndrome. Lancet 1994;344:817-9.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.
- Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev 2002;(1):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.
- Singhal AB, Caviness VS, Begleiter AF, et al. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58:130-3. 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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(28):e4135. View abstract.
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