Sulfonamide Allergy and Possible Cross-Reactivity

True allergic reactions are IgE-mediated immune reactions and are also termed type I reactions, where the spectrum of presentation may range from urticaria to severe anaphylactic shock. Currently, 3% of the patients who use sulfonamide antibiotics develop an allergic reaction, with the most common being the development of a maculopapular rash. Sulfonamides are chemical compounds that can be further divided into 3 groups based on differences in their structural makeup. Several cases reviewing the cross-reactivity between sulfonamide antibiotics and nonantibiotics have suggested an increased risk of cross-reactivity and therefore recommend other treatment strategies to avoid a possible anaphylactic reaction; however, other reports argue that patients with a history of sulfonamide allergy who received sulfonamide nonantibiotics did not experience any adverse reactions. Pertinent data extracted from these studies are reviewed and evaluated.