Several small studies have compared 5-HTP to standard antidepressants. 16 The best one was a 6-week study of 63 people given either 5-HTP (100 mg 3 times daily) or an antidepressant in the Prozac family (fluvoxamine, 50 mg 3 times daily). 17 Researchers found equal benefit between the supplement and the drug. However, 5-HTP caused fewer and less severe side effects