Uses. Acyclovir is used to treat infections caused by certain types of viruses. It treats cold sores around the mouth (caused by herpes simplex), shingles (caused by herpes zoster), and chickenpox. The improved acyclovir bioavailability achieved with valacyclovir has allowed testing of the hypothesis that greater acyclovir exposure early in the recurrence will be effective for treatment of cold sore episodes. Therefore, we conducted two studies that evaluated the efficacy and safety of 1- and 2-day treatment regimens of valacyclovir in the treatment of cold sore outbreaks. Acyclovir is approved by the Food and Drug Administration as a prescription drug that is commonly used as a topical, injectable, and oral treatment for genital herpes and cold sores. Oral anti-virals indicated for cold sore treatment ACYCLOVIR: 400mg 5 times per day for 5 days (adults); 15mg/kg (max of 200mg per dose) 5 times per day for 5 days VALACYCLOVIR: 2000 mg BID for 2 doses (every 12 hours) Acyclovir is an antiviral drug, often used to treat the herpes simplex virus that causes cold sores. While the virus itself can never be fully cured, drugs like acyclovir can help to control cold sore outbreaks and lessen the symptoms. For the subgroup of patients who started acyclovir treatment in the prodrome or erythema stage, the mean duration of pain significantly decreased (2.5 days vs 3.9 days for placebo, P=.02), as did healing time to loss of crust (5.8 days vs 7.9 days for placebo, P=.03). Detailed Acyclovir dosage information for adults and children. Includes dosages for Herpes Simplex - Suppression, Herpes Simplex Labialis, Herpes Zoster and more; plus renal, liver and dialysis adjustments. Though Acyclovir is generally a prescription medication, they are widely distributed all over the Internet for the millions of cold sore and fever blister sufferers all over the world. In this article, I’m going to teach you how to use acyclovir for cold sores. Ninety percent of all people get at least one cold sore in their life. Acyclovir (Zovirax) treats infections caused by the herpes viruses including genital herpes, cold sores, shingles and chicken pox. Includes Acyclovir side effects, interactions and indications. Includes Acyclovir side effects, interactions and indications.