A dermatologist will conduct a physical examination of your skin blisters. They will look for an indicator of the condition called Nikolsky’s sign. A positive Nikolsky’s sign is when your skin shears off easily when the surface is wiped sideways with a cotton swab or a finger.

Your doctor may then take a biopsy of the blister, which involves removing a piece of tissue for analysis, and looking at it under a microscope to confirm the diagnosis. The biopsy may be treated in the laboratory with chemical