Antivirals like Famvir are also prescribed for oral herpes (fever blisters, Herpes 1) on the lip and face. Many doctors prescribe an antiviral to "head off" or as a preventive against a fever blister outbreak along the nerve root. An outbreak post op or just pre op could compromise the healing time for facial nerves. (At least that is the theory as it was explained to me). If it was prescribed for you by one doctor, I am surprised another doctor told you not to take it. But if you haven't had any new fever blisters you are safe anyway.