Blisters become hard callus, may be fungal infection caused by the disease later, you can continue to use antifungal drugs; if it is caused by friction, you can use topical skin softening medication. 1. fungal infections: for example, fungal infections caused by tinea pedis caused by blisters after medication, blisters hardened into a callus is part of the normal recovery process, should continue to apply antifungal medication, such as ketoconazole ointment, terbinafine cream, etc., will generally gradually fall off. 2. caused by friction: due to excessive friction caused by skin exudate blisters, blisters hardened into a callus, you can apply urea ointment, salicylic acid ointment, vitamin E cream and other drugs, local softening symptomatic treatment, pay attention to avoid friction factors. Blisters hardened into calluses, it is recommended to go to the hospital for examination, clear cause, follow the doctor’s instructions for treatment.