Severe hypersensitivity reaction upon rechallenge with trimethoprim-sulfamethoxazole in a patient with AIDS.

A patient with acquired immunodeficiency syndrome (AIDS) developed rash, fever, neutropenia, and elevated liver function tests during an initial course of trimethoprim-sulfamethoxazole (TMP-SMX) therapy. Upon reexposure to the drug, the patient experienced a severe anaphylactoid reaction associated with pulmonary edema and rhabdomyolysis. Reactions associated with TMP-SMX rechallenge in this patient population have been previously reported but have not been associated with this degree of severity. TMP-SMX therapy should be instituted with extreme caution in patients with AIDS who have demonstrated a prior hypersensitivity reaction to the drug.