5-Hydroxytryptophan (5-HTP or 5-Hydroxy-l-tryptophan) is an amino acid that converts in the brain into a chemical called serotonin. Serotonin is an important brain chemical involved in mood, behavior, appetite, and sleep. Serotonin is known as 5-HT, or 5-hydroxytryptamine, and is found in many places in the body particularly the brain, gastrointestinal system, and blood cells. It is believed that, due to the stress-filled era of modern living, people have lower levels of serotonin in the brain. This can cause people to become overweight, crave sugar and other carbohydrates, experience bouts of depression, get frequent headaches, and have vague muscle aches and pain. By raising the levels of serotonin in the brain, these problems can be corrected. 5-HTP was introduced to the over the counter market in 1994. Even though it is relatively new to the United States health food industry, it has been available through pharmacies for several years. Since the 1970抯 it has been available in several European countries as a medicine. With it being so new, the safety issues are still unclear. Little is known about the chronic use of 5-HTP and it is recommended to take 5-HTP in the minimum effective dosage and to avoid prolonged use. A tolerance may develop in people with continual use. No reports of life threatening side effects have been reported from use of 5-HTP.