Systemic lupus erythematosus induced by interferon β1 therapy in a patient with multiple sclerosis.

Drug-induced lupus erythematosus is defined as a lupus-like syndrome temporally related to a drug exposure. We report a 34-year-old woman with multiple sclerosis who developed, while being treated with interferon β-1a, myalgia and associated with wrist synovitis. Clinical and immunologic investigations were in favor of systemic lupus erythematosus. Interferon therapy was maintained. Under corticosteroids and antipaludeen treatment, the patient did not develop any other lupic manifestations.