5-HTP is a common over the counter product that is sold in natural food stores and via the Internet. It is claimed to improve sleep problems, depression, anxiety, compulsive disorders, restless leg syndrome, migraines, fibromyalgia, and low pain threshold.Increased levels of 5-HIAA in the urine can be a of a specific type of cancer, called carcinoid tumor. Urinary 5-HIAA levels can also be increased by a number of food products and drugs. Oral 5-HTP is not known as a cause of elevation of 5-HIAA in urine. However, recent information suggests that 5-HTP may cause an increase.