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Famciclovir

Antiviral

Brand names:

Famvir®

Often used for:

Viral infections

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What is famciclovir?

Famciclovir is an antiviral medication. It works to control illness due to herpes virus infections in patients with weak immune systems. It may be used for shingles, cold sores, or genital herpes.

Patients receiving famciclovir may have regular blood draws to check blood counts and monitor liver and kidney function. The dose of famciclovir may change based on the results of lab tests.

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May be taken as a tablet by mouth

 
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Possible side effects

  • Nausea and vomiting
  • Headache
  • Loss of appetite
  • Abdominal pain
  • Fatigue or weakness
  • Rash, itching, hives
  • Diarrhea
  • Low blood counts (may cause increased risk of infection, bleeding, anemia and/or fatigue)
  • Changes in menstrual cycle
  • Changes in liver function (increases in ALT/AST/bilirubin)

Not all patients who take famciclovir will experience these side effects. Common side effects are in bold, but there may be others. Please report all suspected side effects to your doctor or pharmacist.

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Tips for families

Be sure to discuss these and other recommendations with your doctor or pharmacist.

  • Famciclovir tablets contain lactose.
  • Patients should tell their doctor if they are pregnant or breastfeeding.
  • Finish all doses of the medicine as instructed by a doctor or pharmacist.

Famciclovir at home:

  • This medicine may make you dizzy or drowsy. Do not drive or do anything that could be dangerous until you see how this medicine affects you.
  • Famciclovir may be taken with or without food.
  • Give a missed dose as soon as possible. If it is near the time for the next dose, skip the dose. Do not give 2 doses at the same time.
  • Store famciclovir at room temperature.
  • Do not use the medicine past the expiration date.
  • Follow instructions for safe storage and disposal.

Learn More About Famciclovir

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Always check the medication label. Many medicines look the same. Do not take any new medicine, including over-the counter medicines or supplements, without checking with your doctor or pharmacist. Talk to your doctor or pharmacist about what to do in the case of a missed dose, allergic reaction, or medical emergency. 

This information is not intended to be a complete guide and is not a substitute for talking with your provider. Medicine names, appearance, formulas, or availability may vary by clinic location. Always follow the instructions given by your care team.