Famvir (Famciclovir)

What Famvir is and what it is used for

Famvir is an antiviral medication that stops the virus causing the infection from multiplying. Because the virus multiplies very early in the infection, treatment works best when you start taking Famvir as soon as the first symptoms appear. In Canada, this early-start approach is commonly emphasized in prescribing and dermatology practice for viral skin conditions.

Famvir is used in adults to treat shingles (herpes zoster) and recurrent genital herpes outbreaks. Famvir is not a cure for herpes infections.

Shingles (herpes zoster)

Shingles (herpes zoster) is a viral infection caused by the varicella zoster virus, the same virus that causes chickenpox.

The safety and effectiveness of Famvir for shingles affecting the eye(s) (ophthalmic zoster) have not been established.

Genital herpes

Genital herpes is a viral infection caused by herpes simplex virus type 1 or 2. It is usually spread through sexual contact. It causes blisters and burning or itching around the genitals, which may be painful.

Famvir is used to treat recurrent genital herpes outbreaks in adults. People who have frequent genital herpes outbreaks can also take Famvir as suppressive therapy to help reduce how often outbreaks happen. The safety and effectiveness of suppressive therapy beyond 1 year have not been established.

Before you take Famvir

Do not take Famvir

If you are allergic (hypersensitive) to famciclovir, any of the ingredients in Famvir, or penciclovir (for example, Denavir® (penciclovir cream)). Ask your doctor for advice if you think you may be allergic.

Take special care with Famvir

If you have kidney problems, or have had them in the past, your doctor may decide to prescribe a lower dose of Famvir.

If you have problems with your immune system, or if you have liver problems, tell your doctor before taking Famvir.

Children and adolescents (below the age of 18 years)

Famvir is not recommended for use in children and adolescents.

Prevent passing genital herpes to others

If you are taking Famvir to treat or suppress genital herpes, or if you have had genital herpes in the past, you should still practise safer sex, including using condoms. This is important to help reduce the risk of passing the infection on to others. You should not have sex if you have genital sores or blisters.

Taking other medications

Tell your doctor or pharmacist if you are taking, or have recently taken, any other medications, including medications obtained without a prescription.

It is especially important to tell your doctor or pharmacist if you take probenecid, as it may increase penciclovir levels.

Taking Famvir with food and drink

You can take Famvir with or without food.

Pregnancy and breast-feeding

Ask your doctor or pharmacist for advice before taking any medication.

If you are pregnant or plan to become pregnant, tell your doctor. It is not known whether Famvir will harm your unborn baby.

If you are breast-feeding or plan to breastfeed, tell your doctor. It is not known whether Famvir passes into breast milk or how it may affect a breastfed baby.

Driving and using machines

Famvir can cause dizziness, drowsiness, or confusion. Do not drive or use machines if you have any of these symptoms while taking Famvir.

Important information about some of the ingredients of Famvir

If your doctor has told you that you have an intolerance to some sugars, such as lactose, contact your doctor before taking this medication. Famvir 125 mg, 250 mg, and 500 mg tablets contain lactose.

How to take Famvir

Always take Famvir exactly as your doctor has told you. Check with your doctor or pharmacist if you are not sure.

The daily dose and length of treatment will depend on the type of viral infection you have - see below. Your doctor will prescribe the correct dose for you.

For best results, start taking the medication as soon as possible after the first signs and symptoms appear.

Do not have sexual contact with anyone if you have symptoms of genital herpes, even if you have started treatment with Famvir. This is because you could pass the herpes infection to your partner.

If you have or have had kidney problems, your doctor may decide to give you a lower dose of Famvir.

Dose for shingles

If you have a normal immune system, the recommended dose is one 500 mg tablet three times a day for seven days.

Dose for genital herpes

The dose depends on the stage of your infection.

Famvir is not indicated for the first outbreak of genital herpes.

To treat recurrent outbreaks, the recommended dose is: 1000 mg twice daily for 1 day.

To help prevent future outbreaks (suppressive therapy), the recommended dose is one 250 mg tablet twice a day. Your doctor will tell you how long you need to keep taking your tablets.

The safety and effectiveness of Famvir have not been established in immunocompromised patients, except for treatment of recurrent orolabial or genital herpes in HIV-infected adults (500 mg twice daily for 7 days).

If you take more Famvir than you should

If you have taken more tablets than you were told to take, or if someone else accidentally takes your medication, go to your doctor or hospital right away for advice. Show them your pack of tablets.

Taking too much Famvir may affect the kidneys. In people who already have kidney problems, it may rarely lead to kidney failure if the dose is not lowered correctly.

If you forget to take Famvir

If you miss a dose of Famvir, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and take your next dose as scheduled. Do not take two doses at the same time to make up for a missed dose.

If you have any further questions about the use of this product, ask your doctor or pharmacist.

Possible side effects

Like all medications, Famvir can cause side effects, although not everyone gets them.

The most common side effects reported are headache and nausea.

Serious side effects of Famvir include:

• Severe blistering of the skin or mucous membranes of the lips, eyes, mouth, nasal passages, or genitals (these could be signs of a serious allergic skin reaction).
• Unexplained bruising, reddish or purplish patches on the skin, or nosebleeds (these could be signs of a decrease in the number of blood platelets).

Contact a doctor or go to the emergency department at your nearest hospital right away if you get any of these effects.

• Headache
• Feeling sick (nausea)
• Vomiting
• Dizziness
• Drowsiness
• Rash
• Itching

If any of the side effects become serious, or if you notice any side effects not listed in this leaflet, tell your doctor or pharmacist.

How to store Famvir

Keep out of the reach of children.

Do not use Famvir after the expiry date stated on the label. The expiry date refers to the last day of that month.

Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F).

Do not use Famvir if you notice the pack is damaged or shows signs of tampering.

Medications should not be disposed of in wastewater or household waste. Ask your pharmacist in Canada how to dispose of medications you no longer need. These measures will help protect the environment.