The valtrex (valacyclovir) dosage for treating cold sores is: Acyclovir does not cure cold sores or genital herpes, does not prevent outbreaks of these conditions, and does not stop the spread of. Cold Sores Treatment Plan Valacyclovir 1000mg - Roman 29 votes) acyclovir cream is used to treat cold sores (fever blisters; Does valacyclovir work for cold sores . One study found that valacyclovir may help shorten the duration of a cold sore outbreak by about 1 day. 2 grams every 12 hours for 1 day (2 doses total) while these are the recommended dosages for valacyclovir for cold sores, your doctor may advise that you use a different dosage based on their best judgment. Valtrex (valacyclovir) is a prescription medication used to treat shingles, cold sores, genital herpes. For adults treating a first outbreak of genital herpes, 1,000mg of valacyclovir two times daily for a total of 10 days. Valtrex, which contains the active ingredient valacyclovir, can help your cold sores clear...