NHS information about aciclovir, including what it's used for, who can use it, how to use it and side effects. Aciclovir, also known as acyclovir, [4] is an antiviral medication. [5] It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles. [6] Acyclovir is an antiviral drug. It slows the growth and spread of the herpes virus in the body. Acyclovir will not cure herpes, but it can lessen the symptoms of the infection. Acyclovir is used to treat infections caused by herpes viruses, such as genital herpes, cold sores, shingles, and chicken pox. Acyclovir is used to treat viral infections like chickenpox, herpes zoster (shingles) and genital herpes (a sexually transmitted disease). Acyclovir is in a class of medications called antivirals. It works by stopping the spread of the virus in the body. Although acyclovir will not cure shingles or genital herpes, it does help relieve the pain and discomfort and helps the sores heal faster. This medicine is available only with your doctor's prescription. This product is available in the following dosage forms: What is acyclovir used for? Acyclovir is an antiviral medicine commonly used for the following conditions caused by herpes viruses. Acyclovir may also be used for other conditions as. Acyclovir is widely used in the treatment of herpesvirus infections, particularly herpes simplex virus (HSV) and varicella-zoster virus (VZV). An overview of the mechanisms of action of and resistance to acyclovir and its major clinical uses will be provided here.