Valtrex^® is a prescription medication that is used to treat conditions related to the herpes virus, including shingles, cold sores, and genital herpes. The drug cannot cure these conditions, but it can help to heal the outbreak quicker than if you were not taking the medication. Valtrex works by preventing the virus from multiplying. As with any medication, there are potential side effects of Valtrex, such as headaches, nausea, and depression. The drug comes in caplet form and can be taken up to three times a day, depending on what it is being used for. In order for the medication to work properly, be sure to take Valtrex as prescribed.