Herpes-associated erythema multiforme can be controlled by continuous suppressive treatment with oral acyclovir. Erythema multiforme is not prevented if oral acyclovir is administered after a herpes simplex recurrence is evident and it is of no value after erythema multiforme has occurred. There is some question whether continuous topical treatment with acyclovir to sites of recurrent herpes will sometimes prevent erythema multiforme. Erythema multiforme may be precipitated by orolabial and genital recurrences and by recurrences on skin of the buttocks and other sites. Some herpetic recurrences are associated with erythema multiforme and some are not and episodes of erythema multiforme are not always associated with clinical herpetic recurrences.