Differential diagnosis of erythema multiforme major are :
-drug eruption
-bullous pemphigoid
-pemphigus
-dermatitis herpetiformis
-contact dermatitis
-paraneoplastic pemphigus
-cicatricial pemphigoid
-pemphigus foliaceus
-linear IgA dermatosis
-epidermolysis bullosa
-porphyria cutanea tarda
-Graft versus host disease
-herpes gestationis
-staphylococcal scalded skin syndrome
-drug eruption
-bullous pemphigoid
-pemphigus
-dermatitis herpetiformis
-contact dermatitis
-paraneoplastic pemphigus
-cicatricial pemphigoid
-pemphigus foliaceus
-linear IgA dermatosis
-epidermolysis bullosa
-porphyria cutanea tarda
-Graft versus host disease
-herpes gestationis
-staphylococcal scalded skin syndrome