The L-tryptophan-related eosinophilia myalgia syndrome (EMS), characterized by eosinophilia, myalgias, myositis, scleroderma-like skin fibrosis and fasciitis, occurred in 1989 in over 1500 patients who had ingested L-tryptophan for sleep disturbances and depression. The identical clinical syndrome has also occurred in subjects ingesting L-5-hydroxytryptophan (L-5-HTP).