Sunscreen use is recommended, since sun exposure may activate herpes simplex virus (HSV) that can trigger EM. Radiation and ultraviolet light should be avoided where possible.
In the case of frequent or severe recurrences, HSV titres may suggest the trigger, even when no documented HSV lesions have been found. Oral valaciclovir suppression on a daily basis can be of benefit in preventing disease recurrences. Since the lesions arise quickly, taking valaciclovir treatment doses may be too late to prevent the hypersensitivity reaction.
In the rare setting of drug-related disease, strict drug avoidance is needed to prevent recurrences.[2]Sokumbi O, Wetter DA. Clinical features, diagnosis, and treatment of erythema multiforme: a review for the practicing dermatologist. Int J Dermatol. 2012 Aug;51(8):889-902.
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-4632.2011.05348.x/full
http://www.ncbi.nlm.nih.gov/pubmed/22788803?tool=bestpractice.com
[4]Bastuji-Garin S, Rzany B, Stern RS, et al. Clinical classification of cases of toxic epidermal necrolysis, Stevens-Johnson syndrome, and erythema multiforme. Arch Dermatol. 1993 Jan;129(1):92-6.
http://www.ncbi.nlm.nih.gov/pubmed/8420497?tool=bestpractice.com
[5]Assier H, Bastuji-Garin S, Revuz J, et al. Erythema multiforme with mucous membrane involvement and Stevens-Johnson syndrome are clinically different disorders with distinct causes. Arch Dermatol. 1995 May;131(5):539-43.
http://www.ncbi.nlm.nih.gov/pubmed/7741539?tool=bestpractice.com
[9]Auquier-Dunant A, Mockenhaupt M, Maldi L, et al. Correlations between clinical patterns and causes of erythema multiforme majus, Stevens-Johnson syndrome, and toxic epidermal necrolysis: results of an international prospective study. Arch Dermatol. 2002 Aug;138(8):1019-24.
https://jamanetwork.com/journals/jamadermatology/fullarticle/478935
http://www.ncbi.nlm.nih.gov/pubmed/12164739?tool=bestpractice.com