On Nov. 24, 1989, the U.S. Food and Drug Administration (FDA) issued a nationwide recall of all over-the-counter dietary supplements containing 100 milligrams or more of L-Tryptophan. The recall was due to a clear link between the consumption of L-tryptophan tablets and its association with a U.S. outbreak of Eosinophilia Myalgia Syndrome (EMS), characterized by fatigue, shortness of breath, and other symptoms.

EMS is a heterogeneous, multi-organ disease that appears to have a sub-acute onset. The disorder is characterized initially by eosinophilia and severe myalgia. A host of other systemic systems may include, joint pain, weakness, fever, dyspnea, cough, fatigue, edema, rash, sclerodermaform skin changes, hair loss, and neuropathy.

By 1990 the Centers for Disease Control and Prevention confirmed over 1,500 cases of EMS, including 38 deaths, and FDA prohibits the importation of l-tryptophan.