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). -
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). 
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.-
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). -
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).
