Acyclovir is used to treat many medical conditions, including herpes infections of the skin, mouth, mucous membranes, genital herpes, herpes zoster (shingles), and chickenpox. Acyclovir is used as a topical treatment, as well as a systematic. Although Acyclovir does not permanently cure herpes, it relieves pain and accelerates the length of the infection. For Acyclovir treatment, follow the instructions provided by a physician. The adverse effects associated with Acyclovir nausea, vomiting, upset stomach, loss of appetite, diarrhea, headache, dizziness or weakness should disappear, as the body adjusts. Acyclovir should be used for the full course of the treatment. Never missing Acyclovir doses and double dosing are not recommended.