Dermatological Emergencies: Erythema Multiforme

Erythema multiforme (EM) has two streams: erythema multiforme minor and erythema multiforme major.

Erythema multiforme minor affects men more than women. Approximately 50% of affected patients are under the age of 20. The condition refers to the eruption of regular lesions, which is accompanied by mild fever and malaise. It lasts from one to three weeks.

Erythema multiforme minor is usually caused by certain infections such as herpes simplex, viral infections, or as side effects from vaccination (for example, smallpox, tetanus, and diphtheria). Drugs are among the rarest causes of EM minor.

Erythema multiforme major is rare among the general patient population; however, those who suffer from human immunodeficiency virus infection are among the most affected. It usually presents as mucosal eruption of erosions and blisters on the lips, conjunctivae, oropharynx, and/or genitalia, accompanied by fever and prostration. Target lesions and/or acral bullae may also be present.

Erythema multiforme major is a result of drug eruption. The most common drugs that cause erythema multiforme major are antibiotics, allopurinol, anticonvulsants, and sulphonamides. Infections are among the rarest causes of erythema multiforme major, but eruption can occur in those infected with Mycoplasma pneumoniae.

The underlying causes and complications associated with erythema multiforme are investigated through the collection of skin swabs for herpes simplex and bacterial culture, full blood count, and viral titres, with particular attention to mycoplasma.

Erythema multiforme minor can resolve within 10 days. Symptomatic treatment may include the prescription of oral antihistamines or topical corticosteroids. Bullae are typically incised and drained.

Erythema multiforme major is more serious and challenging to treat, requiring hospitalization for supportive care. This includes mouth care involving frequent antiseptic and analgesic mouth washes. Intravenous fluid replacement may also be performed. Oral corticosteroids are to be avoided.