Skip to main content




What is famciclovir?

Famciclovir (also called Famvir®) is used to treat viral infections. Famciclovir is available as 125-mg and 250-mg white round tablets and as a 500-mg white oval tablet. All are taken by mouth.

Possible side effects of famciclovir

  • Nausea
  • Headache
  • Diarrhea
  • Feeling tired
  • Vomiting
  • Feeling drowsy
  • Loss of appetite
  • Stomach pain

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse.

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Special instructions for famciclovir

  • If your kidney function is decreased, the dose of famciclovir will be decreased. You should monitor how much you urinate each day to make sure that this amount does not decrease. You should call your doctor if you notice a decrease in your daily urine output. It could mean that famciclovir is making your kidney function worse.
  • Do not stop taking famciclovir until you have taken all doses, even if you start feeling better.
  • If you miss a dose, take that dose as soon as you remember as long as the next scheduled dose is more than 4 hours away. If your next dose is due in less than 4 hours, do not take the missed dose. Never take 2 doses at one (1) time.
  • Store famciclovir at room temperature in a dry place.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).