# Acute Generalised Exanthematous Pustulosis

> Acute generalised exanthematous pustulosis for NEET-PG Dermatology, covering sterile drug-induced pustules, histology and the psoriasis mimic.

- Canonical URL: https://prepelephant.com/topics/neet-pg/dermatology/acute-generalised-exanthematous-pustulosis
- Exam / course: NEET-PG · Subject: Dermatology
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: IADVL Textbook of Dermatology; Rook's Textbook of Dermatology
- How to cite: "Acute Generalised Exanthematous Pustulosis", PrepElephant, https://prepelephant.com/topics/neet-pg/dermatology/acute-generalised-exanthematous-pustulosis

## Direct answer

Acute generalised exanthematous pustulosis is a rapidly evolving, sterile pustular eruption, usually drug-induced, that appears on oedematous erythema within 48 hours of exposure. It involves the face and skin folds with fever and neutrophilia, and the pustules resolve within about two weeks of stopping the drug. Aminopenicillins, macrolides, diltiazem and hydroxychloroquine are common culprits, so the drug history decides both diagnosis and treatment.

## What you must remember

- **Onset:** pustules develop within 48 hours of the culprit drug, as a sudden crop on swollen erythema.
- **Distribution:** the face, skin folds and trunk are involved early and spread quickly.
- **Systemic features:** fever and neutrophilia are typical, and they help separate the condition from a simple drug rash.
- **Histology:** subcorneal, non-follicular pustules with neutrophils and eosinophils, often with spongiform change.
- **Culprits:** aminopenicillins, macrolides, diltiazem and hydroxychloroquine are the commonest implicated drugs.
- **Resolution:** pustules dry within days, and scaling or desquamation follows over about two weeks.
- **Management:** stop the culprit, use topical steroids and emollients, and reserve systemic steroids for extensive or severe disease.
- **Recurrence:** re-exposure to the drug produces a faster and more severe relapse, so avoidance is essential.

## Separating AGEP from pustular psoriasis

A 33-year-old woman develops sterile pustules on the face and neck within two days of starting azithromycin, with a temperature of 38.5 degrees. The clinician must decide between acute generalised exanthematous pustulosis and pustular psoriasis, because the treatments differ.

1. **Check the timeline:** an eruption within 48 hours of a new drug, with fever, favours AGEP, whereas pustular psoriasis usually has a long history of plaques.
2. **Look at the base:** AGEP pustules sit on oedematous erythema in the face and folds, while psoriatic pustules arise on a background of plaques with silvery scale.
3. **Examine the nails and joints:** nail pitting and arthritis point towards psoriasis rather than AGEP, and their absence supports the drug-induced diagnosis.
4. **Send a biopsy:** subcorneal pustules with eosinophils favour AGEP, while Munro microabscesses in the stratum corneum favour psoriasis.
5. **Check the blood:** neutrophilia and raised inflammatory markers support AGEP, and a full blood count with renal and liver function guides drug safety.
6. **Stop the drug and treat:** withdraw the culprit, apply topical steroids and emollients, and reserve systemic therapy for extensive or severe cases.

## Where the exam tries to catch you

Two traps dominate AGEP questions, and both involve treating the wrong disease.

- **Trap:** labelling a sudden pustular rash after antibiotics as pustular psoriasis. **Correct:** rapid onset, fever and resolution after stopping the drug point to AGEP, so psoriasis treatment would be wrong.
- **Trap:** continuing the drug because the rash is sterile and not infective. **Correct:** a sterile rash still needs the culprit stopped, since continued exposure prolongs the eruption and risks relapse.
- **Trap:** treating the pustules with systemic antibiotics for suspected infection. **Correct:** the pustules are sterile, and the antibiotic may itself be the culprit and add no benefit.

## Frequently asked questions

### How quickly does acute generalised exanthematous pustulosis appear after a drug?

Acute generalised exanthematous pustulosis usually appears within 48 hours of starting the culprit drug. Its abrupt onset is one of the features that distinguishes it from pustular psoriasis, which evolves over days to weeks.

### What histology supports acute generalised exanthematous pustulosis?

Subcorneal pustules with neutrophils and eosinophils, often with spongiform change, support acute generalised exanthematous pustulosis. Munro microabscesses in the stratum corneum are more typical of psoriasis and argue against this diagnosis.

### Which drugs cause acute generalised exanthematous pustulosis most often?

Aminopenicillins, macrolides, diltiazem and hydroxychloroquine are commonly implicated in acute generalised exanthematous pustulosis. A careful drug history covering the preceding two days is essential, because many patients take several medicines at once.

### Does acute generalised exanthematous pustulosis need systemic steroids?

Most cases of acute generalised exanthematous pustulosis resolve after stopping the culprit drug, with topical care and supportive measures. Systemic corticosteroids are reserved for extensive or severe disease, because the eruption usually settles within about two weeks.