Famciclovir

Sounds like 'fam-SYE-kloe-vir'

Key points about famciclovir

  • Famciclovir is used to treat repeated cold sore infections and reduces the severity and how long you have a cold sore.
  • Famciclovir is only available in Aotearoa New Zealand as tablets.
  • Famciclovir is also called Famciclovir Once.
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Famciclovir is an antiviral medicine used to treat cold sores (herpes labialis) around your mouth, lips, nostrils or nose. It must be used as soon as possible after the first symptoms of a cold sore appear, eg, tingling, itching, burning, redness, or swelling. Famciclovir shouldn't be used if a hard crust has already formed on your cold sore.

It works by stopping the herpes simplex virus that causes the infection from replicating (making copies of itself). It doesn't cure the infection or kill the virus, but reduces the severity of the infection and helps the cold sore heal faster. The virus that causes this infection continues to live in your body. Read more about what can trigger the virus on the cold sores page.

Famciclovir can be purchased from your pharmacy without a prescription. Talk to your pharmacist to check if it's suitable for you. Famciclovir is available as 500 milligram tablets.

  • The usual dose of famciclovir is 1500mg which is 3 tablets taken together in one dose.
  • Always take your famciclovir exactly as directed by your healthcare provider. The instructions on the pack will tell you how much famciclovir to take, how often to take it, and any special instructions.

How to take famciclovir

  • Swallow your famciclovir tablets with a glass of water.
  • Take 3 famciclovir tablets together as one dose. 
  • You can take famciclovir with or without food.
  • Drink plenty of water while taking famciclovir to keep your kidneys working well (unless your doctor advises you otherwise). 

  • Are you under 18 years of age?
  • Are you pregnant (hapū) or breast-feeding?
  • Do you have liver or kidney problems?
  • Are you immunocompromised?
  • Are you taking or using any other medicines? 
  • Have you ever had an allergic reaction to a medicine?

If so, it’s important that you tell your healthcare provider before you start taking famciclovir. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care or at a reduced dose.

Like all medicines, famciclovir can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects

What should I do?
  • Headache
  • Nausea (feeling sick)
  • Diarrhoea (runny poos)    
  • These are common and usually settle after a few hours.
  • Tell your healthcare provider if these bother you.
  • Dizziness
  • Be careful when driving or using tools until you know how this medicine affects you.
  • Don't drink alcohol.
  • Signs of an allergic reaction such as skin rash, itching, swelling of the lips, face, and mouth or difficulty breathing
  • Tell your doctor immediately or ring Healthline 0800 611 116.

Cold sores
Herpes simplex virus

The following links have more information on famciclovir.

Famciclovir(external link) NZ Formulary
Famciclovir Once(external link) (ApoHealth Famciclovir Once) Medsafe NZ Consumer Medicine Information

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Credits: Healthify He Puna Waiora editorial team. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

Last reviewed:

Page last updated:

Read more at: https://healthify.nz/medicines-a-z/f/famciclovir/
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