A to Z: Erythema Multiforme

May also be called: Erythema Multiforme Minor; Erythema Multiforme Major; Stevens-Johnson Syndrome

Erythema multiforme (EM) is a hypersensitive reaction to an infection or, in some cases, a medication. This reaction causes a rash that appears as red, target-shaped ("bulls-eye") patches or sores on the skin.

More to Know

Most cases of erythema multiforme (air-ah-THEE-mah mul-ti-FOR-me) are thought to be an overreaction of the body's immune system to an infection, which leads to the rash. More than half of cases are associated with the herpes simplex virus (the virus that causes cold sores). But other viruses, bacteria like mycoplasma, and fungi also can trigger the rash. In some cases, EM happens after taking certain medications.

The rash, which may itch or burn, often begins on the arms, hands, legs, and feet, but can occur on the face, neck, and torso. The rash will go away within 1-4 weeks, but may leave darker spots on the skin for a few months.

Other symptoms can include a low-grade fever and mild aches in joints and muscles. In a few severe cases, mouth sores or blisters can develop and the condition can be life threatening.

Keep in Mind

Erythema multiforme is not contagious and goes away on its own without treatment. Most people who get it experience no long-term effects, but some can have recurrences. Suspected cases of EM should be evaluated by a doctor, who can look for possible causes that may need specific treatment.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.