Table 1.

Distinguishing features of generalized bullous fixed drug eruption and Stevens-Johnson syndrome

Characteristic	Generalized bullous fixed drug eruption	Stevens-Johnson syndrome
Implicated drugs	Antibiotics, nonsteroidal anti-inflammatory drugs, acetaminophen, antiepileptic drugs, antimalarials2	Allopurinol, antiepileptic drugs, antibiotics, nonsteroidal anti-inflammatory drugs, nevirapine2
Onset after inciting agent	Onset within 30 minutes to 12 hours3	Onset within 6 to 21 days4
Site specificity	Reoccurs at same site: trunk, extremities; spares mucosa or mild mucosal involvement3	Mucosal involvement in >90%: oral, ocular, urogenital4
Cutaneous lesions	Well-circumscribed annular red/brown macules or plaques with overlying flaccid bullae1	Painful, ill-defined, coalescing, erythematous macules with purpuric centers progressing to vesicles and bullae1
Histopathology	Scattered apoptotic keratinocytes, lichenoid inflammatory infiltrate with eosinophils, dermal macrophages, and pigment incontinence5	Partial to full-thickness epidermal necrosis, pauci-inflammatory infiltrate with variable number of eosinophils5