Bullous drug eruption is a term used to describe a heterogeneous group of bullous diseases that are induced by medications. The following disease entities are included under the term bullous drug eruption:

• Bullous fixed drug eruption (BFDE) – Can be single, multiple, or generalized. Generalized bullous fixed drug eruption (GBFDE) develops in 50% of affected patients. Due to widespread blistering, it can mimic Stevens-Johnson syndrome (SJS). GBFDE tends to occur more rapidly after drug exposure (48 hours versus 1-3 weeks), have more well-circumscribed individual lesions, and have less mucosal involvement than SJS, but can be life-threatening due to widespread denudation. Compared to localized BFDE, GBFDE tends to occur in older individuals, possibly due to repeated culprit drug exposure. More than 100 medications have been implicated. Vaccinations have also been reported to be triggers. Foods can cause a similar eruption called fixed food eruption (FFE).
• SJS / toxic epidermal necrolysis (TEN) – A rare, severe, and sometimes life-threatening drug eruption.
• Drug-induced autoimmune blistering diseases (eg, linear IgA bullous dermatosis [LABD], drug-induced bullous pemphigoid, drug-induced pemphigus) – Autoimmune blistering disease that may be drug-induced. Penicillamine and captopril have been implicated in the causation of pemphigus vulgaris; vancomycin, lithium, angiotensin converting enzyme (ACE) inhibitors, and diclofenac have been implicated in LABD; and there are a host of less-well-studied drug associations for bullous pemphigoid.
• Drug-induced pseudoporphyria – Photoexposed skin fragility and blistering that resembles porphyria cutanea tarda and is usually drug-induced.
• Acute generalized exanthematous pustulosis (AGEP) – Characterized by tiny pustules on a background of erythema, AGEP may rarely have bullae and resemble SJS/TEN.

Depending on the underlying pathogenesis, bullae may be tense (eg, drug-induced bullous pemphigoid) or flaccid with a positive Nikolsky sign (eg, SJS/TEN, pemphigus vulgaris). Patients may have mucosal involvement, in which case SJS/TEN should be ruled out. Diagnosis often requires biopsy for hematoxylin and eosin (H&E) stain, often in conjunction with direct immunofluorescence (DIF) when there is concern for autoimmune blistering disease (eg, LABD, drug-induced bullous pemphigoid, drug-induced pemphigus). Prognosis varies widely based on underlying subtype of bullous disease. Of the disease entities listed, SJS/TEN carries the worst prognosis.