The mucosal involvement gives the appearance of Stevens-Johnson syndrome. Erythema multiforme is a mild, self-limited, often recurrent condition, whereas Stevens-Johnson syndrome is a severe, potentially life-threatening reaction. In the past, the two forms were believed to represent ends of a spectrum of disease, but now both are regarded as distinct entities. Stevens-Johnson syndrome is usually related to medication use.
Recurrent episodes, single mucosal involvement, lack of drug history and evidence of herpes labialis indicates that the patient is having EM Minor and is unlikely to proceed to the severe form in spite of mucosal involvement.