RESUMO
Bactrim consists of the sulfonamides trimethoprim and sulfamethoxazole. These induce relatively frequent adverse drug reactions, including allergic reactions ranging from urticaria to anaphylaxis. Either component can be the causative allergen, so it is necessary to determine which has caused an allergic reaction to prevent further allergy. We report the case of a 46-year-old male with chronic renal failure who experienced anaphylactic shock twice after ingesting trimethoprim-sulfamethoxazole, as was proven by the medical history and skin prick testing. Enzyme-linked immunoassays and enzyme-linked allergen inhibition assays for allergen-specific IgE antibody for the five components of Bactrim showed that sulfamethoxazole was the causative allergen.
