A Case of Bullous Pemphigoid Triggered by COVID-19 Infection in a Patient Receiving a Dipeptidyl Peptidase-4 Inhibitor

Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used for the treatment of type 2 diabetes mellitus. Recently, their association with drug-induced bullous pemphigoid (BP) has attracted increasing attention. In this report, we present a case of an 84-year-old woman who developed BP after COVID-19 infection while taking a DPP-4 inhibitor. The temporal relationship between drug administration, viral infection, and onset of autoimmune disease indicates a possible interaction between COVID-19-induced immune dysregulation and DPP-4 inhibition. The coexistence of these factors may increase the risk of developing BP in older patients with diabetes, which warrants careful monitoring.