Two cases with bullous pemphigoid relapsed after using interleukin‐17A inhibitors for psoriasis: A paradoxical reaction

Biological drugs, including IL-17A inhibitors, have become the first-line treating options for moderate to severe psoriasis, and reports show a beneficial effect of IL-17A inhibitors on bullous pemphigoid. Here, we report two cases of bullous pemphigoid in remission that experienced severe flares during treatment with two major IL-17A inhibitors, i.e., ixekizumab or secukinumab for their psoriasis vulgaris. The patient with bullous pemphigoid induced by secukinumab became very recalcitrant to control the relapse. This is by far the first and paradoxical report on the IL-17A inhibitors having a negative effect on bullous pemphigoid patients in previously stable status. Our reports of these two cases alert clinicians to be careful when using IL-17A in pemphigoid patients. We also suggest that patients with psoriasis vulgaris should be asked for a detailed history of pemphigoid and its BP180 autoantibodies status be checked before using these biologicals.