Description: Acyclovir is used to treat herpes infections of the skin, lip, and genitals; herpes zoster (shingles); and chickenpox. It does not cure herpes infections but decreases pain and itching and promotes healing. Topical acyclovir does not prevent the recurrence of sores but may decrease pain and itching if applied when the earliest symptoms first appear. Oral acyclovir decreases the frequency and severity of recurrent sores, but it is used only by people with severe herpes infections because of possible adverse effects.