Famvir (Famciclovir) is an antiviral agent. Famvir relieves the symptoms of herpes zoster infection (shingles) or genital herpes infection. Famciclovir will not cure shingles or genital herpes; it will help the blisters heal faster and reduce the duration of pain and discomfort. Famciclovir is also used to reduce the number of episodes of genital herpes infection.