Erythema multiforme is a skin reaction that can be triggered by an infection or medication. It’s usually mild and goes away in a few weeks.
But there’s also a rare, severe form that can affect the mouth, genitals and eyes and can be life-threatening. This is known as erythema multiforme major.
Erythema multiforme mainly affects adults under 40, although it can occur at any age.
The rash comes on suddenly and develops over a few days. It tends to start on the hands or feet, before spreading to the limbs, upper body and face.
The cause of erythema multiforme is often unclear, but some cases are the result of a reaction to an infection or medication.
The condition can’t be passed from person to person.