Erythema multiforme

Erythema multiforme is a reaction pattern, not a primary disease. It is characterised by round to oval triphasic iris-like (target) lesions, usually on the face, and hands or feet.

Patients with erythema multiforme are generally well. If a patient has any systemic symptoms, severe symptoms, or extensive cutaneous or mucosal involvement, consider the possibility of Stevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). See Types of cutaneous drug reactions, their time courses, and some commonly implicated drugs for signs, symptoms and commonly implicated drugs in SJS and TEN. If these cutaneous drug reactions are suspected, urgently refer to hospital for assessment and management because the rash may progress rapidly with high mortality; patients with loss of skin require expert nursing care.

True erythema multiforme is rare, and common causes are herpes simplex virus reactivation, Mycoplasma pneumoniae and drugs (eg nonsteroid anti-inflammatory drugs [NSAIDs], penicillins, phenytoin, barbiturates, sodium valproate). Erythema multiforme is most commonly misdiagnosed as annular urticaria.

Treatment of mild forms of erythema multiforme is supportive. Remove triggers (eg drugs), if possible. Apply an emollient (see Emollient types and properties) and a potent topical corticosteroid. Use:

1betamethasone dipropionate 0.05% ointment topically, once daily for 2 weeks betamethasone dipropionate betamethasone dipropionate betamethasone dipropionate

OR

1betamethasone valerate 0.1% ointment topically, once daily for 2 weeks betamethasone valerate betamethasone valerate betamethasone valerate

OR

1mometasone furoate 0.1% ointment topically, once daily for 2 weeks. mometasone furoate mometasone furoate mometasone furoate

Antiviral prophylaxis may be indicated in patients with frequent severe recurrences that are associated with herpes simplex virus.