Famciclovir is used in the treatment of herpes zoster, which is painful rash with blisters on the skin in a localised area.

It is used in suppressing recurring instances of herpes simplex 2 type virus, which causes sores around the mouth. It is also used in HIV patients to prevent the recurring instance of herpes simplex virus.

Mild fever, nausea, headache and mild stomach upset are common side effects. Mood changes, kidney problems, dizziness and drowsiness are rare, but more severe side effects.

People with a medical history of kidney problems and nursing mothers should inform the doctor. Pregnant women should use this medicine only under doctor's supervision.