Erythema multiforme is a type of hypersensitivity reaction. It is usually divided into erythema multiforme major and minor forms. It can affect the skin and mucous membranes, and commonly affects the eyes and oral cavity.
The minor form of erythema multiforme can be triggered by stress, infection, or medication. Sometimes there is no obvious trigger. Treatment is aimed at keeping the patient well hydrated and nourished especially if the oral cavity is involved, since eating can be very painful. Care must be taken to prevent infection of the ulcers. Antibiotics and anti-inflammatory agents may be necessary.
If there is an obvious trigger, removal will often cause prompt recovery, though recurrences can occur.
Erythema multiforme major (Stevens-Johnson syndrome) is more likely to be triggered by medications. The symptoms are similar to erythema multiforme minor, but are more severe and widespread. Suspected erythema multiforme major must be treated as a medical emergency. The severe and extensive lesions may become life threatening, and careful supportive therapy and withdrawal of any identifiable triggers must be accomplished promptly.