Valtrex (Valacyclovir) is an antiviral used in patients with normal immune systems to treat herpes zoster infections (shingles) or to treat or suppress genital herpes. This medicine may be used in combination with safe sex practices in patients with genital herpes to help reduce the risk of spreading the condition to others. This medicine may also be used for cold sores (herpes simplex) or other conditions as determined by your doctor.