Famvir Famvir Famvir is a prescription drug manufactured by Novartis Pharmaceuticals Inc for the treatment of shingles and genital herpes. Shingles is a painful rash with red pimples on the trunk of the body usually on the back. Because the same virus that causes chickenpox causes it, only people who have had chickenpox can get shingles. Famvir works best in people age 50 or over, when prescribed for shingles. Famvir Valtrex is only adults with healthy immune system and is available only with prescription. There is no cure for herpes, and even while undergoing treatment; it may be possible to spread herpes. If you are taking Famvir Valtrex to reduce the risk of spreading genital herpes always be sure to use safer sex practices. It is not known if Famvir Valtrex minimizes the risk of spreading genital herpes in same sex couples.