- Herpes simplex 1, which causes cold sores
- Herpes simplex 2, which causes genital herpes
- Varicella-zoster, which causes both chickenpox and shingles
- Epstein-Barr virus, which causes infectious mononucleosis
Acyclovir inhibits the replication of viral DNA needed for the virus to reproduce. Virally infected cells absorb more acyclovir than normal cells and convert more of it to an active form, prolonging its antiviral activity where it is most needed. Acyclovir may reduce the severity and duration of a shingles attack if given soon after the onset of symptoms.
For more information, see: Acyclovir.