Stevens-Johnson syndrome (erythema multiforme major) is a rare but serious condition that causes sores that are like boils on the mucous membranes of the mouth, nose, genitals, and eyelids. A widespread skin rash of irregularly shaped, flat, purplish red spots also develops, which may be painful.

The skin rash may develop on any part of the body but often begins on the face, neck, chin, and trunk. Sores that develop on the mucous membranes weep a thick gray-yellow fluid. When these sores occur on the inside of the eyelids, the fluid hardens into a crust. When sores occur in the mouth, eating and drinking can be painful.

Stevens-Johnson syndrome is usually caused by a reaction to a medicine. When this occurs, the person should stop taking the medicine.

The condition may also result from an infection or a vaccination. Sometimes Stevens-Johnson syndrome develops as a reaction to donated body tissues or blood cells, which is called a graft-versus-host disease. In some people the cause is unknown.

Recovery from Stevens-Johnson syndrome may be slow, taking up to 6 weeks. Treatment includes a soft diet and oral and IV fluids to prevent dehydration. A doctor will treat mouth and eye sores. In some cases, skin grafts are needed.