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This monograph is intended to serve as a guide to industry for the preparation of Product Licence Applications (PLAs) and labels for natural health product market authorization. It is not intended to be a comprehensive review of the medicinal ingredient.


  • Text in parentheses is additional optional information which can be included on the PLA and product label at the applicant's discretion.
  • The solidus (/) indicates that the terms and/or statements are synonymous. Either term or statement may be selected by the applicant.


October 30, 2018

Proper name(s), Common name(s), Source material(s)

Table 1. Proper name(s), Common name(s), Source material(s)
Proper name(s) Common name(s)
Source material(s)
Proper name(s) Part(s)
  • 5-Hydroxy-L-tryptophan
  • L-5-Hydroxytryptophan
  • L-5-HTP
  • L-5-Hydroxytryptophan

Griffonia simplicifolia


References: Proper names: O'Neil et al. 2001; Common names: O'Neil et al. 2001; Source material: Lemaire and Adosraku 2002, Fellows and Bell 1970.

Route of Administration


Dosage Form(s)

This monograph excludes foods or food-like dosage forms as indicated in the Compendium of Monographs Guidance Document.

Acceptable dosage forms for the age category listed in this monograph and specified route of administration are indicated in the Compendium of Monographs Guidance Document.

Use(s) or Purpose(s)

  • Helps to promote healthy mood balance (Pöldinger et al. 1991; Zmilacher et al. 1988; Nakajima et al. 1978).
  • Helps to relieve symptoms of fibromyalgia (Nicolodi and Sicuteri 1996; Sarzi Puttini and Caruso 1992; Caruso et al. 1990).
  • Helps to reduce the severity and duration of migraine headaches when taken as a preventative (prophylactic) (Titus et al. 1986; Bono et al. 1984; Sicuteri 1973).
  • To be used with a program of reduced intake of dietary calories and increased physical activity (if possible) to help in weight management by reducing carbohydrate cravings (Cangiano et al.1998; Cangiano et al. 1992; Ceci et al. 1989).
  • Used as a sleep aid (Soulairac and Lambinet 1977; Wyatt et al. 1971).



Adults 18 years and older


Healthy mood balance

150 - 300 milligrams of 5-HTP, per day; Not to exceed 200 milligrams per single dose (Pöldinger et al. 1991; Nakajima et al. 1978).

Relief of symptoms of fibromyalgia

300 - 400 milligrams of 5-HTP, per day; Not to exceed 200 milligrams per single dose (Nicolodi and Sicuteri 1996; Caruso et al. 1990).

Migraine prophylaxis

200 - 600 milligrams of 5-HTP, per day; Not to exceed 200 milligrams per single dose (Titus et al. 1986; Sicuteri 1973).

Weight management

750 - 900 milligrams of 5-HTP, per day; Not to exceed 300 milligrams per single dose (Cangiano et al. 1998; Cangiano et al. 1992; Ceci et al. 1989).

Sleep aid

100 - 200 milligrams of 5-HTP, per day (Soulairac and Lambinet 1988; Soulairac and Lambinet 1977; Wyatt et al. 1971).

Direction(s) for use

All uses (excluding sleep aid)

To minimize the risk of gastrointestinal side effects, start dosing at 100 mg, 2 - 3 times per day and slowly increase to effective dose over 2 week period (Birdsall 1998).

Sleep aid

Take 30 - 45 minutes before bedtime (Pizzorno and Murray 2006).

All uses (excluding weight management)

Take with food (Pöldinger et al. 1991).

Weight management

Take 30 minutes prior to a meal (Cangiano et al. 1998; Cangiano et al. 1992; Ceci et al. 1989).

Duration(s) of Use

Healthy mood balance

  • Use for at least 1 week to see beneficial effects (Nakajima et al. 1978).
  • Consult a health care practitioner/health care provider/health care professional/doctor/ physician for use beyond 1 year (Nicolodi and Sicuteri 1996).

Relief of symptoms of fibromyalgia

  • Use for at least 2 weeks to see beneficial effects (Caruso et al. 1990).
  • Consult a health care practitioner/health care provider/health care professional/doctor/ physician for use beyond 1 year (Nicolodi and Sicuteri 1996).

Migraine prophylaxis

Use for at least 2 - 3 weeks to see beneficial effects (Sicuteri 1973).

Products for migraine prophylaxis and providing 200 - 400 mg of 5-HTP, per day

Consult a health care practitioner/health care provider/health care professional/doctor/ physician for use beyond 1 year (Nicolodi and Sicuteri 1996).

Products for migraine prophylaxis and providing more than 400 mg of 5-HTP, per day

Consult a health care practitioner/health care provider/health care professional/doctor/ physician for use beyond 6 months (Titus et al. 1986).

Weight management

Consult a health care practitioner/health care provider/health care professional/doctor/physician for use beyond 12 weeks (Cangiano et al. 1992).

Sleep aid

No statement required.

Risk Information

Caution(s) and warning(s)

Sleep aid

Consult a health care practitioner/health care provider/health care professional/doctor/physician if sleeplessness persists continuously for more than 4 weeks (chronic insomnia) (Berardi et al. 2002; Dipiro et al. 2002).

All uses (except sleep aid)

Consult a health care practitioner/health care provider/health care professional/doctor/physician if symptoms persist or worsen.

All uses

  • Consult a health care practitioner/health care provider/health care professional/doctor/ physician prior to use if you are pregnant or breastfeeding.
  • Consult a health care practitioner/health care provider/health care professional/doctor/ physician prior to use if you are taking carbidopa or drugs/supplements with serotonergic activity. These may include, but are not limited to, L-tryptophan, Sadenosylmethionine (SAMe), St. John's wort, antidepressants, pain killers, over the counter cough and cold medication containing dextromethorphan, anti-nausea medication and anti-migraine medication (Mayo Clinic Staff 2007; Turner et al 2006).
  • Stop use and consult a health care practitioner/health care provider/health care professional/ doctor/physician if you show signs of weakness, oral ulcers, abdominal pain accompanied by severe muscle pain or if you experience skin changes (Das et al. 2004; Lampert et al. 1992; Sternberg et al. 1980).
  • Avoid taking with alcohol or products that cause drowsiness.


Do not use this product if you have scleroderma (Lampert et al. 1992; Sternberg et al. 1980).

Known adverse reaction(s)

  • Some people may experience drowsiness. Exercise caution if operating heavy machinery, driving a motor vehicle or involved in activities requiring mental alertness (Caruso et al. 1990; Zmilacher et al. 1988; Takahashi et al. 1976).
  • Some people may experience diarrhea, nausea, vomiting and abdominal pain (Turner et al. 2006; Byerley et al. 1987).

Non-medicinal ingredients

Must be chosen from the current Natural Health Products Ingredients Database (NHPID) and must meet the limitations outlined in the database.

Storage conditions

No statement required


  • The finished product specifications must be established in accordance with the requirements described in the Natural and Non-prescription Health Products Directorate (NNHPD) Quality of Natural Health Products Guide.
  • The medicinal ingredient must comply with the requirements outlined in the NHPID.

References Cited

  • Berardi RR, DeSimone EM, Newton GD, Oszko MA, Popovich NG, Rollings CJ, Shimp LA, Tietze KJ, editors. Handbook of Nonprescription Drugs: An Interactive Approach to Self-Care, 13th edition. Washington (DC): American Pharmaceutical Association; 2002.
  • Birdsall TC. 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Alternative Medicine Review 1998;3(4):271-280.
  • Bono G, Micieli G, Sances G, Calvani M, Nappi G. L-5HTP treatment in primary headaches: an attempt at clinical identification of responsive patients. Cephalalgia 1984;4(3):159-165.
  • Byerley WF, Judd LL, Reimherr FW, Grosser BI. 5-Hydroxytryptophan: a review of its antidepressant efficacy and adverse effects. Journal of Clinical Psychopharmacology 1987;7(3):127-137.
  • Cangiano C, Ceci F, Cascino A, Del Ben M, Laviano A, Muscaritoli M, Antonucci F, RossiFanelli F. Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan. American Journal of Clinical Nutrition 1992;56(5):863-867.
  • Cangiano C, Laviano A, Del Ben M, Preziosa I, Angelico F, Cascino A, Rossi-Fanelli F. Effects of oral 5-hydroxy-tryptophan on energy intake and macronutrient selection in non-insulin dependent diabetic patients. International Journal of Obesity and Related Metabolic Disorders 1998;22(7):648-654.
  • Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V. Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. Journal of International Medical Research 1990;18(3):201-209.
  • Ceci F, Cangiano C, Cairella M, Cascino A, Del Ben M, Muscaritoli M, Sibilia L, Rossi Fanelli F. The effects of oral 5-hydroxytryptophan administration on feeding behavior in obese adult female subjects. Journal of Neural Transmission 1989;76(2):109-117.
  • Das YT, Bagchi M, Bagchi D, Preuss HG. Safety of 5-hydroxy-L-tryptophan. Toxicology Letters 2004;150(1):111-122.
  • Dipiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: a pathophysiologic approach, 5th edition. New York (NY): The McGraw-Hill Companies, Inc.; 2002.
  • Fellows LE, Bell EA. 5-hydroxy-L-tryptophan, 5-hydroxytryptamine and L-tryptophan-5hydroxylase in Griffonia simplicifolia. Phytochemistry 1970;9(11):2389-2396.
  • Lampert A, Joly P, Thomine E, Ortoli JC, Lauret P. [Scleroderma-like syndrome with bullous morphea during treatment with 5-hydroxytryptophan, carbidopa and flunitrazepam]. Annales de Dermatologie et de Vénéréologie 1992;119(3):209-211 (in French).
  • Lemaire PA, Adosraku RK. An HPLC method for the direct assay of the serotonin precursor, 5hydroxytrophan, in seeds of Griffonia simplicifolia. Phytochemical Analysis 2002;13(6):333337.
  • Mayo Clinic Staff. Serotonin Syndrome. Rochester (MN): Mayo Foundation for Medical Education and Research; 2007. [Accessed 2018 August 7]. Available from:
  • Nakajima T, Kudo Y, Kaneko Z. Clinical evaluation of 5-hydroxy-L-tryptophan as an antidepressant drug. Folia Psychiatrica et Neurologica Japonica 1978;32(2):223-230.
  • Nicolodi M, Sicuteri F. Fibromyalgia and migraine, two faces of the same mechanism. Serotonin as the common clue for pathogenesis and therapy. Advances in Experimental Medicine and Biology 1996;398:373-379.
  • O'Neil MJ, Smith A, Heckelman PE, Budavari S, editors. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 13th edition. Whitehouse Station (NJ): Merck & Co., Inc; 2001.
  • Pizzorno JE, Murray MT, editors. Textbook of Natural Medicine, Volume 1, 3rd edition. St. Louis (MO): Churchill Livingstone Elsevier; 2006.
  • Pöldinger W, Calanchini B, Schwarz W. A functional-dimensional approach to depression: serotonin deficiency as a target syndrome in a comparison of 5-hydroxytryptophan and fluvoxamine. Psychopathology 1991;24(2):53-81.
  • Sarzi Puttini P, Caruso I. Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study. Journal of International Medical Research 1992;20(2):182-189.
  • Sicuteri F. The ingestion of serotonin precursors (L-5-hydroxytryptophan and L-tryptophan) improves migraine headache. Headache 1973;13(1):19-22.
  • Soulairac A, Lambinet H. [Clinical studies of the effect of the serotonin precursor, L-5hydroxytryptophan, on sleep disorders]. Schweizerische Rundschau für Medizin Praxis 1988;77(34a):19-23 (in French).
  • Soulairac A, Lambinet H. [Effect of 5-hydroxytryptophan, a serotonin precursor, on sleep disorders]. Annales Médico-Psychologiques 1977;1(5):792-798 (in French).
  • Sternberg EM, Van Woert MH, Young SN, Magnussen I, Baker H, Gauthier S, Osterland CK. Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. New England Journal of Medicine 1980;303(14):782-787.
  • Takahashi S, Takahashi R, Masumura I, Miike A. Measurement of 5-hydroxyindole compounds during L-5-HTP treatment in depressed patients. Folia Psychiatrica et Neurologica Japonica 1976;30(4):463-473.
  • Titus F, Dávalos A, Alom J, Codina A. 5-Hydroxytryptophan versus methysergide in the prophylaxis of migraine. Randomized clinical trial. European Neurology 1986;25(5):327-329.
  • Turner EH, Loftis JM, Blackwell AD. Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan. Pharmacology & Therapeutics 2006;109(3):325-338.
  • Wyatt RJ, Zarcone V, Engelman K, Dement WC, Snyder F, Sjoerdsma A. Effects of 5-hydroxytryptophan on the sleep of normal human subjects. Electroencephalography and Clinical Neurophysiology 1971;30(6):505-509.
  • Zmilacher K, Battegay R, Gastpar M. L-5-hydroxytryptophan alone and in combination with a peripheral decarboxylase inhibitor in the treatment of depression. Neuropsychobiology 1988;20(1):28-35.

References Reviewed

  • Agazzi A, De Ponti F, De Giorgio R, Candura SM, Anselmi L, Cervio E, Di Nucci A, Tonini M. Review of the implications of dietary tryptophan intake in patients with irritable bowel syndrome and psychiatric disorders. Digestive and Liver Disease 2003;35(8):590-595.
  • Amer A, Breu J, McDermott J, Wurtman RJ, Maher TJ. 5-Hydroxy-L-tryptophan suppresses food intake in food-deprived and stressed rats. Pharmacology, Biochemistry, and Behavior 2004;77(1):137-143.
  • Auffranc JC, Berbis P, Fabre JF, Garnier JP, Privat Y. [Sclerodermiform and poikilodermal syndrome observed during treatment with carbidopa and 5-hydroxytryptophan]. Annales de Dermatologie et de Venereologie 1985;112(9):691-692 (in French).
  • Battistella PA, Bordin A, Cernetti R, Broetto S, Corra S, Piva E, Plebani M. Beta-endorphin in plasma and monocytes in juvenile headache. Headache 1996;36(2):91-94.
  • Beers MH, Berkow R, editors. The Merck Manual of Diagnosis and Therapy, 17th edition. Whitehouse Station (NJ): Merck & Co., Inc; 1999.
  • Bhushan B, Seth SD, Saxena S, Gupta YK, Karmarkar MG. An adverse reaction to L-5hydroxytryptophan. The American Journal of Psychiatry 1991;148(2):268-269.
  • Boiardi A, Crenna P, Merati B, Negri S, Tansini E, Bussone G. 5-OH-tryptophane in migraine: clinical and neurophysiological considerations. Journal of Neurology 1981;225(1):41-46.
  • Boiardi A, Picotti GB, Di Giulio AM, Bussone G, Galva MD, La Mantia L, Mantegazza P. Platelet met-enkephalin immunoreactivity and 5-hydroxytryptamine concentrations in migraine patients: effects of 5-hydroxytryptophan, amitriptyline and chlorimipramine treatment. Cephalalgia 1984;4(2):81-84.
  • Bono G, Criscuoli M, Martignoni E, Salmon S, Nappi G. Serotonin precursors in migraine prophylaxis. Advances in Neurology 1982;33:357-363.
  • Buckingham J, editor. Dictionary of Natural Products, Version 16:1. Boca Raton (FL): Chapman & Hall/CRC; 2007.
  • Bussone G, Boiardi A, Cerrati A, Girotti F, Merati B, Rivolta G. Monoamine oxidase activities in patients with migraine or with cluster headache during the acute phases and after treatment with L-5-hydroxytryptophan. Rivista Di Patologia Nervosa E Mentale 1979;100(5):269-274.
  • Cangiano C, Ceci F, Cairella M, Cascino A, Del Ben M, Laviano A, Muscaritoli M, RossiFanelli F. Effects of 5-hydroxytryptophan on eating behavior and adherence to dietary prescriptions in obese adult subjects. Advances in Experimental Medicine and Biology 1991;294:591-593.
  • De Benedittis G, Massei R. Serotonin precursors in chronic primary headache. A double-blind cross-over study with L-5-hydroxytryptophan vs. placebo. Journal of Neurosurgical Sciences 1985;29(3):239-248.
  • De Giorgis G, Miletto R, Iannuccelli M, Camuffo M, Scerni S. Headache in association with sleep disorders in children: a psychodiagnostic evaluation and controlled clinical study--L-5HTP versus placebo. Drugs Under Experimental and Clinical Research 1987;13(7):425-433.
  • Ek A, Witkop B. The synthesis of labile hydroxytryptophan metabolites. Journal of the American Chemical Society 1954;76(22):5579-5588.
  • EMEA 2007: European Medicines Agency. London (UK): European Medicines Agency; 2007. [Accessed 2007 July 31]. Available from:
  • Farinelli S, Mariani A, Grimaldi A, Mariani M, Iannessi A, De Rosa F. [Eosinophilia-myalgia syndrome associated with 5-OH-tryptophan. Description of a case]. Recenti Progressi in Medicina 1991;82(7-8):381-384 (in Italian).
  • FDA 2007: Food and Drug Administration. MedWatch Online Voluntary Reporting Form (3500). Rockville (MD): Food and Drug Administration; 2007. [Accessed 2007 July 31]. Available from:
  • FDA 2001: Food and Drug Administration. Information Paper on L-Tryptophan and 5-HydroxyL-Tryptophan. Rockville (MD): Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Nutritional Products, Labeling, and Dietary Supplements; 2001. [Accessed 2007 August 02]. Available from:
  • FDA 1998: Food and Drug Administration. FDA Talk Paper: Impurities Confirmed in Dietary Supplement 5-Hydroxy-L-Tryptophan. Rockville (MD): Food and Drug Administration, US Department of Health and Human Services; 1998. [Accessed 2007 August 02]. Available from:
  • FDA 1992: Food and Drug Administration. "Dear Colleague" Letter Regarding the Research on Eosinophilia-Myalgia Syndrome and Current Regulatory Status of L-Tryptophan. Rockville (MD): Food and Drug Administration, Office of Health Affairs; 1992. [Accessed 2007 August 02]. Available from:
  • Frangatos G, Chubb FL. A new synthesis of 5-hydroxytryptophan. Canadian Journal of Chemistry 1959;37:1374-1376.
  • Fugh-Berman A, Cott JM. Dietary supplements and natural products as psychotherapeutic agents. Psychosomatic Medicine 1999;61(5):712-728.
  • Garcia C. [Mianserin agranulocytosis followed by oxitriptan eosinophilia]. Der Nervenarzt 1992;63(5):303-307 (in German).
  • Genazzani AR, Sandrini G, Facchinetti F, Rizzo V, Alfonsi E, Sances G, Calvani M, Nappi G. Effects of L-5HTP with and without carbidopa on plasma beta-endorphin and pain perception. Possible implications in migraine prophylaxis. Cephalalgia 1986;6(4):241-245.
  • Gijsman HJ, Van Gerven JM, De Kam ML, Schoemaker RC, Pieters MS, Weemaes M, De Rijk R, Van Der Post J, Cohen AF. Placebo-controlled comparison of three dose-regimens of 5hydroxytryptophan challenge test in healthy volunteers. Journal of Clinical Psychopharmacology 2002;22(2):183-189.
  • Goodnick PJ, Sandoval R. Psychotropic treatment of chronic fatigue syndrome and related disorders. Journal of Clinical Psychiatry 1993;54(1):13-20.
  • Guilleminault C, Cathala JP, Castaigne P. Effects of 5-hydroxytryptophan on sleep of a patient with a brain-stem lesion. Electroencephalography and Clinical Neurophysiology 1973;34(2):177-184.
  • Gwaltney-Brant SM, Albretsen JC, Khan SA. 5-Hydroxytryptophan toxicosis in dogs: 21 cases (1989-1999). Journal of the American Veterinary Medical Association 2000;216(12):19371940.
  • Halford JC, Harrold JA, Lawton CL, Blundell JE. Serotonin (5-HT) drugs: effects on appetite expression and use for the treatment of obesity. Current Drug Targets 2005;6(2):201-213.
  • HC 2007: Health Canada. MedEffect Canada: Adverse Reaction Reporting. Ottawa (ON): Health Canada; 2007. [Accessed 2007 July 20]. Available from:
  • Imeri L, Mancia M, Bianchi S, Opp MR. 5-Hydroxytryptophan, but not L-tryptophan, alters sleep and brain temperature in rats. Neuroscience 2000;95(2):445-452.
  • Jacobsen FM, Sack DA, Wehr TA, Rogers S, Rosenthal NE. Neuroendocrine response to 5-hydroxytryptophan in seasonal affective disorder. Archives of General Psychiatry 1987;44(12):1086-1091.
  • Jellin JM. Natural Medicines Comprehensive Database. Stockton (CA): Therapeutic Research Faculty; 1995-2007. [Accessed 2007 September 17]. Available from: s=ND.
  • Juhl JH. Fibromyalgia and the serotonin pathway. Alternative Medicine Review 1998;3(5):367375.
  • Kahn RS, Westenberg HG. L-5-hydroxytryptophan in the treatment of anxiety disorders. Journal of Affective Disorders 1985;8(2):197-200.
  • Kahn RS, Westenberg HG, Verhoeven WM, Gispen-de Wied CC, Kamerbeek WD. Effect of a serotonin precursor and uptake inhibitor in anxiety disorders; a double-blind comparison of 5hydroxytryptophan, clomipramine and placebo. International Clinical Psychopharmacology 1987;2(1):33-45.
  • Klarskov K, Johnson KL, Benson LM, Gleich GJ, Naylor S. Eosinophilia-myalgia syndrome case-associated contaminants in commercially available 5-hydroxytryptophan. Advances in Experimental Medicine and Biology 1999;467:461-468.
  • Maron E, Toru I, Vasar V, Shlik J. The effect of 5-hydroxytryptophan on cholecystokinin-4 induced panic attacks in healthy volunteers. Journal of Psychopharmacology 2004;18(2):194199.
  • Martin TG. Serotonin syndrome. Annals of Emergency Medicine 1996;28(5):520-526.
  • Martinelli I, Mainini E, Mazzi C. [Effect of 5-hydroxytryptophan on the secretion of PRL, GH, TSH and cortisol in obesity]. Minerva Endocrinologia 1992;17(3):121-126 (in Italian).
  • Meyers S. Use of neurotransmitter precursors for treatment of depression. Alternative Medicine Review 2000;5(1):64-71.
  • MHRA 2007: Medicines and Healthcare Products Regulatory Agency: An Executive Agency of the Department of Health. Lambeth (London): Medicines and Healthcare Products Regulatory Agency; 2007. [Accessed 2007 July31]. Available from:
  • Michelson D, Page SW, Casey R, Truchsess MW, Love LA, Milstien S, Wilson C, Massaquoi SG, Crofford LJ, Hallett M, Gold PW, Sternberg EM. An eosinophilia-myalgia syndrome related disorder associated with exposure to L-5-hydroxytryptophan. The Journal of Rheumatology 1994;21(12):2261-2265.
  • Morris AJ, Armstrong MD. Preparation of 5-hydroxy-L-and D-tryptophan. Journal of Organic Chemistry 1957;22:306-308.
  • NIH 2007: National Institutes of Health. ChemIDplus Lite. Bethesda (MD): Specialized Information Services, National Library of Medicine, National Institutes of Health, US Department of Health & Human Services. 5-Hydroxytryptophan; RN: 56-69-9. [Accessed 2007 August 09]. Available from: efault&nextPage=jsp/chemidlite/ResultScreen.jsp&TXTSUPERLISTID=000056699.
  • PDR Health 2007: Drug Information, Nutritional Supplements. 5-Hydroxytryptophan (5-HTP). Montvale (NJ): Thomson PDR; 2007. [Accessed 2007 September 19]. Available from:
  • Petre-Quadens O, De Lee C. 5-Hydroxytryptophan and sleep in Down's syndrome. Journal of Neurological Sciences 1975;26(3):443-453.
  • Pijl H, Koppeschaar HP, Cohen AF, Iestra JA, Schoemaker HC, Frolich M, Onkenhout W, Meinders AE. Evidence for brain serotonin-mediated control of carbohydrate consumption in normal weight and obese humans. International Journal of Obesity and Related Metabolic Disorders 1993;17(9):513-520.
  • Renson J, Goodwin F, Weissbach H, Udenfriend S. Conversion of tryptophan to 5hydroxytryptophan by phenylalanine hydroxylase. Biochemical and Biophysical Research Communications 1961;6(1):20-23.
  • Ribeiro CA. L-5-Hydroxytryptophan in the prophylaxis of chronic tension-type headache: a double-blind, randomized, placebo-controlled study. For the Portuguese Head Society. Headache 2000;40(6):451-456.
  • Santucci M, Cortelli P, Rossi PG, Baruzzi A, Sacquegna T. L-5-hydroxytryptophan versus placebo in childhood migraine prophylaxis: a double-blind crossover study. Cephalalgia 1986;6(3):155-157.
  • Schruers K, Van Diest R, Overbeek T, Griez E. Acute L-5-hydroxytryptophan administration inhibits carbon dioxide-induced panic in panic disorder patients. Psychiatry Research 2002;113(3):237-243.
  • Shaw K, Turner J, DelMar C. Tryptophan and 5-hydroxytryptophan for depression. Oxfordshire (UK): The Cochrane Database of Systematic Reviews; 2002, Issue 1. Art. No.: CD003198. DOI: 10.1002/14651858.CD003198.
  • Sigma-Aldrich 2007: Sigma-Aldrich Corporation. H9772 5-Hydroxy-L-tryptophan Solid. St.Louis (MO): Sigma-Aldrich Co.; 2007. [Accessed 2007 July 30]. Available from:
  • Singhal AB, Caviness VS, Begleiter AF, Mark EJ, Rordorf G, Koroshetz WJ. Cerebral vasoconstriction and stroke after use of serotonergic drugs. Neurology 2002;58(1):130-133.
  • Takahashi S, Kondo H, Kato N. Effect of L-5-hydroxytryptophan on brain monoamine metabolism and evaluation of its clinical effect in depressed patients. Journal of Psychiatry Research 1975;12(3):177-187.
  • TGA 2007: Therapeutic Goods Administration. TGA Adverse Drug Reactions Unit. Symonston (AU): Commonwealth Department of Health and Ageing, Therapeutic Goods Administration. [Accessed 2007 July 31] Available from:
  • The Arthritis Society 2006. Scleroderma. Toronto (ON): The Arthritis Society; 2006. [Accessed 2007 August 07]. Available from:
  • Thorne Research, Inc. 5-Hydroxytryptophan. Alternative Medicine Review 1998;3(3):224-226.
  • Van Praag HM. In search of the mode of action of antidepressants. 5-HTP/tyrosine mixtures in depressions. Neuropharmacology 1983;22(3):433-440.
  • Van Praag HM. Management of depression with serotonin precursors. Biological Psychiatry 1981;16(3):291-310.
  • Van Praag HM. Central monoamine metabolism in depressions. I. Serotonin and related compounds. Comprehensive Psychiatry 1980;21(1):30-43.
  • Van Praag HM, De Haan S. Chemoprophylaxis of depressions. An attempt to compare lithium with 5-hydroxytryptophan. Acta Psychiatrica Scandanavica Supplementum 1981;290:191-201.
  • Van Praag HM, Korf J, Dols LC, Schut T. A pilot study of the predictive value of the probenecid test in application of 5-hydroxytryptophan as antidepressant. Psychopharmacologia 1972;25(1):14-21.
  • Van Vliet IM, Slaap BR, Westenberg HG, Den Boer JA. Behavioral, neuroendocrine and biochemical effects of different doses of 5-HTP in panic disorder. European Neuropsychopharmacology 1996;6(2):103-110.
  • Webb M, Kirker JG. Severe post-traumatic insomnia treated with L-5-hydroxytryptophan. Lancet 1981;1(8234):1365-1366.
  • Westenberg HG, Gerritsen TW, Meijer BA, Van Praag HM. Kinetics of l-5-hydroxytryptophan in healthy subjects. Psychiatry Research 1982;7(3):373-385.
  • WHO 2007: World Health Organization. Uppsala Monitoring Centre. Geneva (CHE): World Health Organization; 2007. [Accessed 2007 August 08]. Available from:
  • Yamada J, Sugimoto Y, Ujikawa M. Involvement of leptin in hypophagia induced by the serotonin precursor 5-hydroxytryptophan (5-HTP) in mice. Biological and Pharmaceutical Bulletin 2006;29(3):557-559.
  • Zarcone VP, Berger PA, Brodie KH, Sack R, Barchas JD. The indoleamine hypothesis of depression: an overview and pilot study. Diseases of the Nervous System 1977;38(8):646-653.