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Erythema multiforme — Clinical Guidelines

Overview

Erythema multiforme (EM) is an immune-mediated skin condition commonly triggered by infections (particularly Mycoplasma pneumoniae), drugs, and occasionally vaccines, characterized by target-like lesions and mucosal involvement 1 4 3.

Diagnosis

Clinical Presentation: Presence of characteristic target or iris lesions, often with mucosal involvement 1.

Laboratory Tests: Not routinely required but may include complete blood count (CBC) to assess for leukocytosis or lymphopenia 4.

Specific Triggers: Identification of potential triggers through history, including recent infections, drug exposures, and vaccinations 1 3.

Management

First-Line Treatment: High-potency topical corticosteroids for mild cases 8.

Adjunctive Treatments: Systemic corticosteroids for moderate to severe cases, especially with significant mucosal involvement 1.

Antiviral Therapy: Considered if herpes simplex virus is suspected as the trigger 1.

Supportive Care: Symptomatic treatment and wound care for extensive lesions 1.

Special Populations

Pediatrics: Mycoplasma pneumoniae is a recognized trigger in children 4.

Comorbidities: Patients with underlying hematologic conditions may exhibit prolonged B-cell lymphopenia post-infection 4.

Key Recommendations

Evaluate seasonal patterns, noting higher incidences in spring and summer, particularly in male patients, when considering EM triggers 1 (Evidence: Moderate).

Consider Mycoplasma pneumoniae as a significant infectious trigger, especially in pediatric and immunocompromised patients 4 (Evidence: Moderate).

Use systemic corticosteroids for severe cases with significant mucosal involvement 1 (Evidence: Moderate).

Monitor for potential drug interactions, particularly with azoles, in patients receiving multiple medications 5 (Evidence: Weak).

Recognize vaccine-induced EM as a possible adverse reaction, warranting careful post-vaccination monitoring 3 (Evidence: Weak).

References

1 Tanaka H, Maezawa M, Hirofuji S, Miyasaka K, Nakao S, Nokura Y et al.. Seasonal Variations in Drug-Related Erythema Multiforme: A Time Series Analysis Using the JADER Database. Biological & pharmaceutical bulletin 2025. link 2 Gross BN, Steib-Bauert M, Kern WV, Knoth H, Borde JP, Krebs S et al.. Hospital use of systemic antifungal drugs: a multi-center surveillance update from Germany. Infection 2015. link 3 Verma P. Erythema multiforme possibly triggered by rabies vaccine in a 10-year-old boy. Pediatric dermatology 2013. link 4 Martire B, Foti C, Cassano N, Buquicchio R, Del Vecchio GC, De Mattia D. Persistent B-cell lymphopenia, multiorgan disease, and erythema multiforme caused by Mycoplasma pneumoniae infection. Pediatric dermatology 2005. link 5 Yu DT, Peterson JF, Seger DL, Gerth WC, Bates DW. Frequency of potential azole drug-drug interactions and consequences of potential fluconazole drug interactions. Pharmacoepidemiology and drug safety 2005. link 6 Miró O, Sacanella E, Nadal P, Lluch MM, Nicolás JM, Millá J et al.. Trichosporon beigelii fungemia and metastatic pneumonia in a trauma patient. European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology 1994. link 7 Gill K, Marrie TJ. Hemophagocytosis secondary to Mycoplasma pneumoniae infection. The American journal of medicine 1987. link90121-5) 8 Lévêque JL, Poelman MC, Legall F, de Rigal J. New experimental approach to measure the skin-reflected light. Application to cutaneous erythema and blanching. Dermatologica 1985. link 9 Helfman RJ. Photodermatitis multiformis acuta. Cutis 1983. link 10 Lambert HP. Syndrome with joint manifestations in association with Mycoplasma pneumoniae infection. British medical journal 1968. link

Erythema multiforme