Compare Valacyclovir vs. Acyclovir

Valacyclovir (Valtrex) and acyclovir (Zovirax) are both antiviral medications used to treat infections caused by the herpes simplex virus and varicella-zoster virus, such as cold sores, genital herpes, and shingles. Valacyclovir is taken orally and is converted into acyclovir in your body. One key difference is that valacyclovir is usually taken twice a day, while acyclovir needs to be taken more frequently, up to 5 times a day. Acyclovir comes in more forms, including oral pills, topical creams, and ointments, whereas valacyclovir is only available as a tablet or a compounded oral suspension. Both medications are available as lower-cost generics. Valacyclovir is often preferred for its simpler dosing schedule, but acyclovir offers more options for different types of applications. Both medications can cause side effects like headaches and nausea, but acyclovir's oral forms can also cause vomiting and diarrhea.