Acute Generalized Exanthematous Pustulosis (AGEP) is a reaction mostly caused by drugs which is characterized by the following features:
- acute ocurrence of dozens to hundreds (to thousends) of sterile, non-follicular, pinhead-sized pustules
- these arise on an edematous erythema
- the lesions are often accentuated in the main folds (although more disseminated patterns with more circinate lesions exist)
- other types of lesions may be present: marked edema of the face, purpura lesions (especially on the legs), Stevens-Johnson-syndrome-like "atypical targets", blisters and vesicles described, but not typical for AGEP. Mucous membrane involvement may occur in about 20% of the cases but usually is mild and remains limited to one location (mostly oral).
- after resolution of pustules a characteristic collarette-like postpustular desquamation can be seen.

Systemic symptoms and laboratory findings most often associated with AGEP are:

- fever
- elevated blood neutrophil counts

AGEP evolves quite rapidly. After withdrawal of the causative drug resolution usually takes place within a few days without specific treatment.