Which antiviral drug is used to treat herpes zoster (shingles)?

Valacyclovir is an antiviral medication that is specifically effective in treating herpes zoster, commonly known as shingles. This drug is a prodrug of acyclovir, meaning that it is converted into acyclovir in the body, which acts by inhibiting viral DNA synthesis. By targeting the herpes virus, particularly varicella-zoster virus which causes shingles, valacyclovir helps reduce the severity and duration of the disease when administered early in the course of the outbreak.

Valacyclovir is preferred in clinical practice for treating shingles due to its effectiveness and favorable dosing regimen, which typically allows for less frequent administration than some other antiviral agents. In contrast, other options listed, such as ribavirin and sofosbuvir, are primarily used for viral infections like hepatitis C and are not indicated for herpes zoster. Famciclovir, while also an effective treatment for herpes zoster, is often used as an alternative but is less commonly the first choice compared to valacyclovir in clinical settings. Therefore, valacyclovir stands out for its specific application and effectiveness against the shingles virus.