Erythema multiforme is a skin condition characterized by acute skin lesions. The name multiforme is due to the presentation of varying lesions, such as macules, papules, vesicles, and bullae. Macules are red or pinkish flat lesions whereas papules are raised lesions. These lesions may become flat and raised patches (called plaques). The typical lesion of erythema multiforme is a target lesion (name is due to its resemblance to a shooting target). This type of lesion is characterized by having three zones: (1) a dark red center of small papule, vesicle, or bulla, (2) a pale intermediate ring or zone, and (3) an outermost ring of erythema. The lesions are due to hypersensitivity to certain triggers. One of the most common triggers is infection (e.g. herpes simplex virus infection). The hypersensitivity reaction may be due to the deposition of immune complexes by a certain trigger. Apart from infection, it may also be triggered by certain medications (e.g. barbiturates, penicillin, anticonvulsants, etc.)
There are two forms of erythema multiforme: (1) erythema multiforme minor and (2) erythema multiforme major. In erythema multiforme minor, the symptoms are usually mild whereas in erythema multiforme major, the symptoms are severe and may be life-threatening.