Bullous Symmetric Drug-Related Intertriginous and Flexural Exanthem Secondary to Trimethoprim/Sulfamethoxazole.

Symmetric drug-related intertriginous and flexural exanthem (SDRIFE) is a rare delayed-type hypersensitivity reaction that is considered a variant of systemic allergic contact dermatitis. It is typically triggered by drugs such as beta-lactam antibiotics or antihypertensives. The reaction presents as erythema with flexural prominence. However, we report a particularly rare blistering variant following administration of trimethoprim/sulfamethoxazole (TMP/SMX). Although the histopathological findings were nonspecific, the distribution and lack of systemic and mucosal involvement allowed distinction from other blistering cutaneous adverse reactions with flexural prominence. This case highlights the importance of differentiating SDRIFE from other drug eruptions with flexural distribution and includes a comprehensive differential diagnosis.