Crusted scabies, a severe form of Sarcoptes scabiei infestation, is increasingly reported in immunocompromised individuals. We present a case of a 77-year-old male with bullous pemphigoid (BP) who developed crusted scabies during treatment with dupilumab, systemic corticosteroids (methylprednisolone 60 mg/day), and methotrexate (15 mg/week). Clinical improvement of crusted scabies was observed after topical 20% sulfur ointment application. However, mite clearance was confirmed via follow-up at one month. We reviewed cases of scabies associated with biologics and emphasize the compounded immunosuppressive risks of corticosteroids, methotrexate, and biologics. Clinicians should maintain high vigilance for parasitic infections in patients on multidrug immunosuppressive regimens.