The acute blistering eruption
A level, distribution and urgency framework for widespread vesicles and bullae.
Updated: 2026-09-13
Written for clinicians and medical students
This section is a teaching reference for doctors, residents and medical students. It is not patient guidance and not a substitute for clinical examination, and it must not be used for self treatment.
Immediate triage
- Mucosal erosions, skin pain, fever, targetoid lesions, epidermal detachment or a newly started high-risk medicine raise concern for Stevens-Johnson syndrome or toxic epidermal necrolysis and require emergency admission [1].
- Grouped painful vesicles suggest herpes infection; a dermatomal pattern supports zoster. Disseminated disease, eye involvement, pregnancy, neonates and immunosuppression require urgent escalation.
- Flaccid bullae suggest an intraepidermal split; tense bullae suggest a subepidermal split, but clinical texture does not replace biopsy.
Diagnostic sampling
- Take swabs or PCR from a fresh vesicle when infection is possible. Culture purulent lesions where bacterial infection is relevant.
- For suspected autoimmune blistering disease, obtain lesional skin for histology and separate perilesional skin for direct immunofluorescence [2].
- Construct a complete medicine timeline covering prescription, over-the-counter and traditional remedies, including drugs stopped during the preceding two months.