How Valacyclovir Works and Clinical Effects
Shingles, chickenpox, cold sores, and genital herpes are caused by a virus. Once a person has been infected with the virus, it never goes away. It remains inactive in certain nerve cells of the body, waiting to become active again. Valacyclovir is an antiviral medication that helps the body fight the infection by preventing the virus from multiplying. When used to treat genital herpes, this drug can help prevent outbreaks from recurring and can help prevent spreading the virus to other people.
Several studies have examined how well valacyclovir treats shingles, cold sores, and genital herpes.
In one study, people younger than 50 years of age with shingles were treated with valacyclovir within three days of the beginning of a rash. In people who were not treated with this medication, it took three days for the formation of new blisters to stop. In the people who were treated with valacyclovir, the blisters stopped forming one day sooner. The drug will not, however, change the length or severity of postherpetic neuralgia, which is severe pain that can occur after the shingles rash has healed. In addition, valacyclovir is not a cure for shingles.
In a study of valacyclovir for cold sores, people were given the drug to take at the first symptoms of a cold sore. The cold sores healed one day faster in people who took valacyclovir compared to people who did not. Although this medication helped cold sores to heal faster, it did not stop the cold sores from appearing once symptoms had started. As with shingles, this is not a cure for cold sores.