Quick Summary
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What do L-tryptophan and 5-HTP do?
L-tryptophan is an essential amino acid naturally found in meats and other foods. It is converted in the body to 5-HTP (which is not found in foods), which is then converted to serotonin and melatonin (see What It Is). L-tryptophan can promote sleep, while 5-HTP has been used as an antidepressant, although this effect has not been well-established. Both have been proposed for other uses based on preliminary evidence (see What It Does).
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Are L-tryptophan and 5-HTP safe?
L-tryptophan from a specific manufacturer caused hundreds of cases of a serious immune disorder, eosinophilia-myalgia syndrome (EMS), in the late 1980s. A more pure form is now sold that seems to be much safer. However, there is still some risk with even pure L-tryptophan, particularly at high doses. 5-HTP in supplements is generally safe, but rare cases of EMS have also been reported. (See Concerns and Cautions).
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Best choice for tryptophan supplements?
CL tested all supplements for a range of impurities. Among those that passed testing and provided the best value, CL selected a Top Pick for L-Tryptophan and a Top Pick for 5-HTP.
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How to take tryptophan?
L-tryptophan is taken for sleep at a dose of about 1 gram (1,000 mg) shortly before bedtime, while other uses have involved higher doses. 5-HTP is taken at a daily dose of about 50 mg to 900 mg depending on the use, and divided during the day. (See What to Consider When Using).
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Safety and side effects of tryptophan:
In addition to the potential risk of EMS and some mild side effects, these supplements should be used with caution in people taking medications that affect serotonin, such as some antidepressants and migraine medications (see Concerns and Cautions).
Products tested in 2018
+— 29 sources
In addition the results of its expert testing, ConsumerLab uses only high-quality, evidence based, information sources. These sources include peer-reviewed studies and information from agencies such as the FDA and USDA, and the National Academy of Medicine. On evolving topics, studies from pre-print journals may be sourced. All of our content is reviewed by medical doctors and doctoral-level experts in pharmacology, toxicology, and chemistry. We continually update and medically review our information to keep our content trustworthy, accurate, and reliable. The following sources are referenced in this article:
- Cangiano, Am J Clin Nutr 1992
- Hartmann, J Psychiatr Res. 1982
- Jahromi, Neurol Sci 2019
- Jangid, Asian J Psychiatr 2013
- Kahn, Int Clin Psychopharmacol 1987
- Li, Nutrients 2025
- Meloni, Sleep Breath 2021 Aug
- Nicolodi, Recent Advances in Tryptophan Research 1996
- Poldinger, Psychopathology 1991
- Thomas, Adv Integ Med 2015
- Wyatt, Electroencephalogr Clin Neurophysiol 1971
- Back, J Rheumatol, 1993
- Bowen, J Behav Med. 1991
- Hartmann, J Nerv Ment Dis. 1979
- Steinberg, Adv Exp Med Biol. 1999
- Allen, Arthritis & Rheumatism 2011
- Auffret, Fund & Clin Pharm Suppl 2013, Abstract P2-204
- Barth, Clin Exp Immunol. 2001
- Burks, AACE Clin Case Rep 2016
- Carcinoid Cancer Foundation Accessed 2022
- Das, Toxicology Letters 2004
- Hallin, Ann Clin Biochem 2013
- Kamb, JAMA 1992
- Klarsov, Tox Letters 2018
- MedWatch Continuing Education Article 1996, p.6
- Ortolani, Clin Case Reports 2019
- Pardo, Gen Hosp Psych 2012
- Preshaw, CMAJ 2008
- Smith, Inflammation Research 2005
You must be a ConsumerLab.com member to get the full test results along with ConsumerLab.com's Top Picks. You'll get results for six supplements: five selected by ConsumerLab.com and one other product that passed the same testing in our voluntary Quality Certification Program. In the review, you'll learn: 
- ConsumerLab's Top Picks for L-tryptophan and 5-Hydroxy-L-tryptophan (5-HTP) supplements based on quality, dose and value
- Which products passed or failed our tests and why
- How L-tryptophan and 5-HTP supplements compare on ingredients, dosage, and cost
- Information about branded L-tryptophan ingredients (such as TryptoPure) and what to look for on the label when choosing an L-tryptophan or 5-HTP supplement
- Dosage of L-tryptophan and 5-HTP for specific uses and the evidence for or against those uses (including sleep, depression, migraine, weight loss, and fibromyalgia)
- Safety concerns, including information about eosinophilia-myalgia syndrome (EMS) associated with use of L-tryptophan and 5-HTP supplements, as well as potential side effects and drug interactions
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