Erythema multiforme is more common in younger males, mainly in the second to fourth decades, but can include children and adolescents (male-to-female ratio, range of 3:2 to 2:1). The condition is rare in children younger than 3 years and in adults older than 50 years.
Many suspected etiologic factors have associated with erythema multiforme. Both erythema multiforme and Stevens-Johnson syndrome may be induced by medications, but infectious agents are also considered to be a major cause of erythema multiforme. However, approximately 50% of cases are idiopathic, with no precipitating factor identified.
Infectious causes are more common in children and are implicated commonly in erythema multiforme. Erythema multiforme minor is regarded as commonly being triggered by herpes simplex virus (HSV; types 1 and 2), and HSV is the most common cause in young adults; in fact, many instances of idiopathic erythema multiforme minor may be precipitated by subclinical HSV infection. Among other infections, Mycoplasma species is another common cause.
Regarding medications, sulfa drugs are the most common triggers (30%). The second most commonly involved agents are the anticonvulsants, including barbiturates,carbamazepine,hydantoin, phenytoin,and valproic acid. Causative antibiotics include penicillin, ampicillin, tetracyclines, amoxicillin, cefotaxime, cefaclor, cephalexin, ciprofloxacin,erythromycin, minocycline, sulfonamides, trimethoprim-sulfamethoxazole, and vancomycin. Antituberculosis agents such as rifampicin, isoniazid, thiacetazone, and pyrazinamide are also known offenders. Antipyretic agents as triggers include analgesics, especially aspirin, as well as phenylbutazone, oxyphenbutazone, and phenazone.
For more on the etiology and epidemiology of erythema multiforme, read here.
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Cite this: William James. Fast Five Quiz: How Much Do You Know About Erythema Multiforme? - Medscape - Feb 15, 2018.