Medication-induced systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease affecting a variety of tissues and organs. The diagnosis of SLE can be made only after several related illnesses are considered and ruled out. The etiology of SLE is unclear, but hormonal factors, environmental toxins, infectious viruses, genetic predisposition, and certain medications have all been considered risk factors. Idiopathic SLE is seen predominantly in young women, with a female:male ratio of approximately 10:1. Each patient is unique and may suffer from a variety of signs and symptoms. The disease is highly unpredictable, and most patients experience flare-ups or fluctuations. The epidemiologic characteristics of medication-induced SLE (MI-SLE) are different from those of idiopathic SLE. Musculoskeletal symptoms predominate the clinical presentation of MI-SLE, while renal and central nervous system involvement is rare or absent. Moreover, a greater percentage of caucasian patients with no female predominance is evidenced in MI-SLE. Several medications can produce positive results on an antinuclear antibody test with or without evidence of clinical lupus. Hydralazine and procainamide are the most commonly recognized medications for inducing SLE. The onset of procainamide- and hydralazine-induced SLE occurs after 50 years of age, which is directly related to the age of the population using these medications. Estrogen-containing oral contraceptives and ibuprofen can exacerbate the symptoms of idiopathic SLE. Clinical judgment dictates the importance of careful patient monitoring and selection of therapy.