Valtrex is the brand name for valacyclovir, an antiviral drug used to treat infections caused by certain types of viruses. In adults, it's prescribed for shingles (herpes zoster), cold sores. Valacyclovir is used to treat herpes zoster (shingles) and genital herpes. It does not cure herpes infections but decreases pain and itching, helps sores to heal, and prevents new ones from forming. Valacyclovir works by interfering with the herpes virus’ ability to make more copies of its DNA. Since the herpes virus is basically just DNA wrapped in a protein coat, the inability to make more DNA means that the virus can’t replicate. Drugs.com provides accurate and independent information on more than 24,000 prescription drugs, over-the-counter medicines and natural products. Find patient medical information for Valacyclovir Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. Learn about the CellCept® $15 Co-pay Card and how CellCept (mycophenolate mofetil) is used for people who have had a kidney, heart, or liver transplant. See full safety for more information. VALTREX (valacyclovir hydrochloride) Caplets. DESCRIPTION. VALTREX (valacyclovir hydrochloride) is the hydrochloride salt of the L-valyl ester of the antiviral drug acyclovir. Valacyclovir 1g Tablets (1000mg). Product Summary This product requires a valid prescription for shipment, please note that HealthWarehouse.com may not accept prescriptions faxed or emailed by patients. Having pain under your right rib cage very often is a cause for concern because this may be a sign of a serious medical condition. Moreover, there are many vital organs such as heart, liver, gall bladder, kidney, and lungs under your right rib cage. Valacyclovir oral tablet doesn’t cause drowsiness, but it can cause other side effects. More common side effects. The more common side effects of valacyclovir can include.