5-HTP supplements may cause cramping, heartburn, gas, diarrhea, irregular heartbeats, rash, and loss of appetite.
Contaminated 5-HTP supplements have led to dangerous side effects, like seizures and a life-threatening neurological condition.
There's no standard dose for 5-HTP. For depression, typical dosages range from 150 to 300 milligrams a day, or sometimes even higher. Ask your doctor for advice.