Definition: Erythema multiforme (EM) is an acute, self-limited, and sometimes recurring skin condition that is considered to be a type IV hypersensitivity reaction.
Etiology: It occurs in response to medicines, infections, or illness
Clinical Features:
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Erythema Multiforme. Symmetric distribution of targetoid macules and plaques. The dusky central zone is more obvious on the left waistline lesions.
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Classification: The condition varies from a mild, self-limited rash to a severe, life-threatening disease.
Etiology: It occurs in response to medicines, infections, or illness
- Herpes simplex virus (HSV; frequently labialis) is strongly associated but may not be clinically apparent. Other viruses, bacteria (M pneumoniae, Chlamydia, Salmonella, Mycobacterium), and fungi (Histoplasma capsulatum, dermatophytes)
- are also associated.
- Medications account for <10%; NSAIDs, sulfonamides, antiepileptics, allopurinol, and antibiotics are
- responsible for the majority.
- Physical factors such as trauma, ultraviolet light exposure, and cold have been reported to elicit EM.
Clinical Features:
- Erythema multiforme (EM) begins with symmetric, erythematous, sharply defined extremity or trunk macules, and evolves into a “targetoid” or “bull’s eye” morphology (a flat, dusky, central area with two concentric, erythematous rings).
- Bullae may appear in the central dusky area (bullous EM).
- The mucous membranes, typically oral, may become involved and raise concern for Steven Johnson Syndrome.
- The typical targetoid lesions allow a diagnosis to be made clinically (bullae, purpura, and mucosal involvement should prompt a dermatology consultation).
- The rash usually persists for 1 to 4 weeks.
Erythema Multiforme. Wrist, hand, and fingers with typical central dusky centers surrounded by the concentric “bull’s eye” rings.
- Erythema multiforme minor—typical targets or raised, edematous papules distributed acrally
- Erythema multiforme major—typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes; epidermal detachment involves less than 10% of total body surface area (TBSA)
- SJS/TEN—widespread blisters predominant on the trunk and face, presenting with erythematous or pruritic macules and one or more mucous membrane erosions; epidermal detachment is less than 10% TBSA for Stevens-Johnson syndrome and 30% or more for toxic epidermal necrolysis.
Management:
- Prevention of HSV recurrences is essential. Antivirals administered after lesions present have minimal clinical impact, but patients should be referred for future prophylaxis consideration.
- Use of facial sunscreens and lip balms may help prevent UVB-induced recurrences.
- Systemic steroids are discouraged but can be considered in atypical presentations.
- With the distinctive clinical findings and no systemic symptoms, patients may be discharged home. Systemic symptoms and atypical presentations require admission and dermatologic consultation.
- Medicines such as antihistamines to control itching
- Moist compresses applied to the skin
- Oral antiviral medicine if the reaction is caused by herpes simplex
- Pain medication recommended by your doctor to reduce fever and discomfort
- Topical anesthetics (especially for mouth sores) to ease discomfort that interferes with eating and drinking
- Antibiotics for skin infections
- Corticosteroids to control inflammation
- Treatment in an intensive care or burn care unit for severe cases, Stevens-Johnson syndrome, and toxic epidermal necrolysis (top layer of skin separates from the lower layers)
- Intravenous immunoglobulins (IVIG, an injection of healthy cells from donors into a vein) to stop the disease process