QT prolongation and torsades de pointes after administration of trimethoprim-sulfamethoxazole

Abstract Trimethoprim-sulfamethoxazole has gained widespread acceptance as an effective broad-spectrum antibiotic since its introduction in 1968. 1 Numerous side effects of this drug have been described, most of which involve the skin, hematopoietic system, gastrointestinal tract and kidney. 2 Cardiac toxicity has rarely, if ever, been encountered. This report describes a patient who presented on 2 occasions with QT-interval prolongation and torsades de pointes after oral administration of trimethoprim-sulfamethoxazole.