Antiviral drugs are medicines that cure or control virus infections. There are several different drugs in the antiviral family, and each is used for specific kinds of viral infections. For example, acyclovir (Zovirax) is used to treat chickenpox, shingles, and the symptoms of herpes virus infections of the genitals, lips, mouth, skin, and brain. The medicine does not cure the infections, but it relieves the discomfort and speeds healing of sores, when they are present. Similarly, valacyclovir (Valtrex) and famciclovir (Famvir) can also be used to relieve the symptoms of shingles. Another antiviral, ganciclovir (Cytovene) is prescribed for cytomegalovirus (CMV) eye infections in people whose immune systems are weakened. Ganciclovir does not cure the CMV infection, but it may keep the symptoms from getting worse. Ganciclovir may also help prevent CMV infections in people who are going to be given drugs or treatments that will weaken...