Eosinophilia, myopathy, and neuropathy in a patient with repeated use of L-tryptophan

In October of 1989, a clustering of cases with eosinophilia lead to the identification of a new syndrome: The eosinophilia myalgia syndrome associated with the use of an L-tryptophan product. Two years before the possible causal relationship between the use of L-tryptophan and the syndrome was described, we treated a patient with eosinophilia, severe neuropathy and disabling myopathy. Immunosuppressive therapy was required to treat the first flare of her disease. With reexposure to L-tryptophan, she relapsed and recovered when L-tryptophan was discontinued. Interestingly, she tolerated a third exposure to L-tryptophan without clinical or laboratory evidence for EMS.