FDA Warns Against L-Tryptophan Use While It Investigates Illnesses

Consumers should stop taking the food supplement L-Tryptophan while authorities investigate at least 30 illnesses that may be associated with the product, the Food and Drug Administration said Saturday.

The product, sold over the counter in tablet and capsule form, has been used by some people with sleeping problems or premenstrual syndrome, the FDA said.

Doctors nationwide have reported more than 30 cases in the last few days of a syndrome characterized by intense eosinophilia, a blood condition, and nearly always involving severe muscle pain, the FDA said.

Some patients have also exhibited weakness, joint pain, swelling of the arms and legs, fever and skin rash, the agency said.

Most of the people affected report having taken L-Tryptophan before becoming ill, but there is not yet sufficient medical evidence to determine a definite link with the product or any of its components, the federal agency said.

L-Tryptophan is sold under a variety of brand names, the FDA said. The illnesses are being investigated by the FDA, the Centers for Disease Control and various state health departments.

The FDA and CDC advised patients with a recent onset of an illness with symptoms like those described to contact their doctor, and recommended that people taking L-Tryptophan not prescribed by a doctor temporarily discontinue use.