Rapidly progressing generalized bullous fixed drug eruption after the first dose of COVID-19 messenger RNA vaccination.

Generalized bullous fixed drug eruption (GBFDE) is a rare type of life-threatening severe cutaneous adverse reaction that is considered a medical emergency because of its potential lethality. Currently, only a few cases of bullous adverse reactions have been reported after coronavirus disease 2019 (COVID-19) vaccination. We describe a patient with distinct clinical, histopathological, and immunological findings that are consistent with severe GBFDE, after Pfizer messenger RNA COVID-19 vaccination. An 83-year-old man presented with a fever and well-demarcated multiple erythematous patches that occurred only 4 h after receiving the first dose of COVID-19 Pfizer vaccination. Over the next few days, the patches became generalized and turned into blisters covering approximately 30% of the body surface. The patient was started on intravenous methylprednisolone and oral cyclosporine. There were no additional blistering lesions after 10 days of treatment, prompting a gradual dose reduction. Our case suggests that a stepwise vaccination adhering to the standard dosing schedule should be warranted with close monitoring for possible significant side effects.