Initial Management of Erythema Multiforme

Priorities in Management

The British Journal of Dermatology recommends documenting all medications taken in the last 2 months, including over-the-counter preparations and complementary therapies, noting start dates, dose increases, and treatment stops 1, 2
Stop any potentially causative medication immediately, as recommended by the British Journal of Dermatology 2
Perform a complete clinical evaluation, including examination of all mucosal sites (eyes, oral cavity, genital, and perianal areas) for involvement, as suggested by the British Journal of Dermatology 2, 1
Document the extent of skin involvement and the presence of characteristic target lesions on a body map, as recommended by the British Journal of Dermatology 2
Measure the percentage of body surface area (BSA) affected, as suggested by the British Journal of Dermatology 2
Evaluate vital signs and oxygen saturation, as recommended by the British Journal of Dermatology 2

Perform serology for Mycoplasma pneumoniae and Chlamydia, as recommended by the British Journal of Dermatology 2
Take skin swabs for HSV and varicella zoster virus, as suggested by the British Journal of Dermatology 2
Obtain a chest radiograph if there is suspicion of pulmonary infection, as recommended by the British Journal of Dermatology 2
Conduct a complete blood count, C-reactive protein, urea, electrolytes, liver function tests, and coagulation studies, as suggested by the British Journal of Dermatology 2
Perform a skin biopsy from lesional skin, adjacent to a blister, for routine histopathology, as recommended by the British Journal of Dermatology 2

For EM Minor (involvement <10% BSA, minimal mucosal involvement): apply emollients and topical corticosteroids of moderate potency, and consider antihistamines for pruritus, as recommended by the Annals of Oncology and Praxis Medical Insights 1, 3
For EM Major (involvement 10-30% BSA or significant mucosal involvement): use high-potency topical corticosteroids and consider oral prednisone, as suggested by the Journal of Clinical Oncology and Annals of Oncology 3, 6
For EM Severe (involvement >30% BSA, extensive mucosal involvement, or systemic symptoms): hospitalize immediately with urgent dermatologic involvement, and consider intravenous methylprednisolone, as recommended by the Journal of Clinical Oncology and Annals of Oncology 3, 4, 6

Do not confuse EM with Stevens-Johnson syndrome (SJS), which presents with widespread erythematous or purpuric macules and blisters, as distinguished by the British Journal of Dermatology 2
Do not delay stopping potentially causative medications, as recommended by the British Journal of Dermatology and Praxis Medical Insights 1, 2
Do not underestimate mucosal involvement, which may require hospitalization for intravenous hydration and pain management, as suggested by the Journal of Clinical Oncology 6
Do not use IgG tests for allergens, as EM is an IgE- and T-cell-mediated condition, as recommended by the Otolaryngology--head and neck surgery journal 7

Re-evaluate at 2 weeks after initiating treatment, and consider escalating therapy or using second-line treatments if there is no improvement or worsening, as recommended by the Annals of Oncology and Praxis Medical Insights 1, 5
Consider dermatologic consultation for follow-up in cases such as psoriasis or for long-term management, as suggested by the Journal of Clinical Oncology 6