# Confirmation of Metformin-Induced Acute Generalized Exanthematous Pustulosis Through a Positive Dechallenge-Rechallenge Test: A Case Report and Review of Cutaneous Manifestations Associated With Metformin

## TL;DR

A 45-year-old man developed a rare skin condition called AGEP after taking metformin, confirmed through rechallenge testing.

## Contribution

This is the first case to confirm metformin-induced AGEP via a positive dechallenge-rechallenge test.

## Key findings

- Metformin can cause acute generalized exanthematous pustulosis (AGEP) in rare cases.
- The case was confirmed through a dechallenge-rechallenge test, strengthening the causal link.
- Dermatologic reactions to metformin are underrecognized and may be more common than previously thought.

## Abstract

Metformin, a widely used first-line treatment for type 2 diabetes mellitus (T2DM), is known for its efficacy and safety profile. While gastrointestinal disturbances are the most commonly reported with metformin use, dermatologic reactions, particularly severe ones, are rare and underrecognized. We present a case of a 45-year-old male with a history of atrial fibrillation who developed acute generalized exanthematous pustulosis (AGEP) after initiating metformin for prediabetes.