In a controlled trial, 5-HTP (300 mg per day) was shown to be effective in reducing many symptoms of fibromyalgia, including pain, morning stiffness, sleep disturbances, and anxiety.²

For depression, 300 mg per day is often effective, though much of the research used 5-HTP in combination with drugs or was uncontrolled.^{3, 4, 5} For insomnia, a single 100-mg nighttime dose of 5-HTP was sufficient to improve the duration and depth of sleep in one placebo-controlled trial.⁶ For migraine headaches, amounts ranging from 400–600 mg per day have been shown to be effective at reducing the frequency and severity of attacks in most clinical trials.^{7, 8, 9, 10, 11} For tension headaches, 100 mg of 5-HTP taken three times per day led to a significant decrease in consumption of pain-relievers, but no significant change in headache duration or intensity.¹²

Appetite reduction and weight loss (averaging 11 pounds in 12 weeks) has occurred with amounts of 600–900 mg daily.^{13, 14} In another clinical trial, 750 mg per day has been shown to be effective at decreasing carbohydrate and fat intake, and promoting weight loss.¹⁵