Famvir Uses, Dosage, Side Effects & Warnings - Drugs.com

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# Famvir

Generic name: famciclovir [ fam-SYE-klo-veer ]
Drug class: Purine nucleosides

Medically reviewed by Philip Thornton, DipPharm. Last updated on Jun 24, 2022.

The Famvir brand name has been discontinued in the U.S. If generic versions of this product have been approved by the FDA, there may be generic equivalents available.

## What is Famvir?

Famvir is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. Famciclovir will not cure herpes, but it can lessen the symptoms of the infections.

Famvir is used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.

Famvir is sometimes used in people with human immunodeficiency virus (HIV) who develop herpes outbreaks around the mouth, genitals, or anal area.

Famvir may not be effective in treating your first episode of genital herpes, but may help prevent future episodes. Famciclovir also may not be effective in Black or African-American people with genital herpes, and may not be effective in any person with shingles (herpes zoster) affecting the eyes.

Famvir is used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles.

There is no cure for herpes and famciclovir will not prevent you from developing symptoms in the future.

## Warnings

You should not take Famvir if you are allergic to famciclovir or penciclovir cream (Denavir). Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared.

Treatment with Famvir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

Herpes infections are contagious and you can infect other people, even while you are being treated with Famvir. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent passing the infection to others.

## Before taking this medicine

You should not use Famvir if you are allergic to famciclovir or penciclovir cream (Denavir).

To make sure Famvir is safe for you, tell your doctor if you have ever had:

- liver disease;

- kidney disease;

- a weak immune system;

- galactose intolerance;

- severe lactase deficiency; or

- glucose-galactose malabsorption.

Tell your doctor if you are pregnant or plan to become pregnant. Herpes can be passed to your baby during childbirth if you have a genital lesion when your baby is born. If you have genital herpes, it is very important to prevent herpes lesions during pregnancy. Take your medicine as directed to best control your infection.

If you are pregnant, your name may be listed on a pregnancy registry to track the effects of famciclovir on the baby.

It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.

Famciclovir is not approved for use by anyone younger than 18 years old.

Famvir pregnancy and breastfeeding warnings (more detail)

## How should I take Famvir?

Take Famvir exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Taking more Famvir than prescribed will not make this medicine more effective

For cold sores or genital herpes, you should start taking Famvir as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

You may take Famvir with or without food.

Lesions caused by herpes viruses should be kept as clean and dry as possible. Wearing loose clothing may help to prevent irritation of the lesions.

To prevent recurrent genital herpes, you may need to take Famvir for up to 1 year. Follow your doctor's instructions.

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses may increase the risk of your virus becoming resistant to medication.

Store at room temperature away from moisture and heat.

## Dosing information

Usual Adult Dose for Herpes Simplex -- Mucocutaneous/Immunocompetent Host:

Genital herpes:
Initial episode: 250 mg orally 3 times a day for 7 to 10 days has been recommended by the US Centers for Disease Control and Prevention (CDC)
Recurrent episodes: 1000 mg orally twice a day for 1 day; alternatively, 125 mg orally twice a day for 5 days has been recommended by the CDC
Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 6 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex -- Mucocutaneous/Immunocompromised Host:

Recurrent episodes of orolabial or genital herpes in HIV-infected patients: 500 mg orally twice a day for 7 days (5 to 10 days recommended by the CDC)
Famciclovir should be started at the first sign or symptom of a recurrent episode (such as tingling, burning, itching, pain, or lesion). The efficacy has not been established if started more than 48 hours after onset of symptoms or lesions.

Usual Adult Dose for Herpes Simplex -- Suppression:

Chronic suppression of recurrent genital herpes:
Immunocompetent patients: 250 mg orally twice a day
HIV-infected patients: 500 mg orally twice a day has been recommended by the CDC
Therapy should be continued as clinically appropriate, although the safety and efficacy of famciclovir therapy beyond 1 year have not been established.

Usual Adult Dose for Herpes Zoster:

500 mg orally every 8 hours for 7 days
Famciclovir is most effective if started within 48 hours of onset of rash. The efficacy has not been established if started more than 72 hours after onset of rash.

Usual Adult Dose for Herpes Simplex Labialis:

Recurrent herpes labialis: 1500 mg orally as a single dose
Famciclovir is most effective if started at the earliest sign or symptom of a cold sore (such as tingling, burning, itching, pain, or lesion).

Detailed Famvir dosage information

## What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

## What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

## What to avoid

Taking this medicine will not prevent you from passing genital herpes to other people. Herpes infections are contagious and you can infect other people even while you are taking Famvir.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Avoid sexual intercourse or use a latex condom to help keep you from spreading the virus to others. Avoid letting infected areas come into contact with other people. Avoid touching an infected area and then touching your eyes. Wash your hands frequently to prevent the spread of infection.

## Famvir side effects

Get emergency medical help if you have signs of an allergic reaction to Famvir: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

- confusion; or

- kidney problems - little or no urination, swelling in your feet or ankles, feeling tired or short of breath.

Common Famvir side effects may include:

- headache; or

- nausea.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Famvir side effects (more detail)

## What other drugs will affect Famvir?

Other drugs may interact with famciclovir, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Famvir drug interactions (more detail)

## Where can I get more information?

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Famvir only for the indication prescribed.

## References

1. Famvir Product Label

## More about Famvir (famciclovir)

- Check interactions
- Reviews (16)
- Drug images
- Side effects
- Dosage information
- During pregnancy
- Generic availability
- Drug class: purine nucleosides
- Breastfeeding
- En español

### Professional resources

- Prescribing Information

### Related treatment guides

- Herpes Simplex, Suppression
- Cold Sores
- Herpes Zoster
- Herpes Simplex, Mucocutaneous/Immunocompromised Host
- Herpes Simplex, Mucocutaneous/Immunocompetent Host

## Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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