Pemphigoid begins with a localized area of erythema or with pruritic urticarial plaques that gradually become more edematous and extensive.

The eruption is often symmetric and generalized. The plaques turn dark red or cyanotic in 1–3 weeks, resembling erythema multiforme, as vesicles and tense bullae rapidly appear on the surface.

Bullae rupture within 1 week, leaving an eroded base that does not spread and that heals rapidly.

Skin biopsy shows subepidermal bullae with an infiltrate of eosinophils within the dermis and blister cavity.