Background:Linear IgA bullous disease (LABD) is a rare mucocutaneous autoimmune subepidermal blistering disease that can affect children mostly of pre-school age. As many as two-thirds of LABD are related to drug ingestion, particularly certain antibiotics, non-steroidal anti-inflammatory drugs and diuretics.Main observation:We describe a 3-year-old boy who presented a CMV infection followed by LABD induced by trimtheporim-sulfametoxazole. To our knowledge, this is the first reported case of trimethoprim-sulfamethoxazole that was confirmed by a rechallenge.Conclusions:Most cases of drug-induced LABD are patients being treated with multiple systemic drugs that could induce the LABD. In the lack of suitable alternative treatment, the identification of the causative drug can be achieved by a rechallenge under close medical surveillance.