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Generic name: famciclovir [ fam-SYE-klo-veer ]
Brand name: Famvir
Dosage form: oral tablet (125 mg; 250 mg; 500 mg)
Drug class: Purine nucleosides

What is Famciclovir?

Famciclovir, an antiviral medication, is used for treating infections that are caused by the herpes virus, such as genital herpes, cold sores, and shingles. Famciclovir may be used to treat herpes outbreaks in the mouth, anal region, or genital area when a person has human immunodeficiency virus (HIV). Famciclovir is not effective for treating the first episode of herpes genitalis, but it can help to prevent further episodes. Famciclovir may also not work in black and African-Americans with genital herpes. It may also not work in anyone with Shingles (Herpes Zoster). Herpes is not curable, and famciclovir does nothing to prevent symptoms from recurring. Famciclovir can be used in other ways not mentioned in the medication guide.

Side effects of Famciclovir

If you experience any of the following signs and symptoms of an allergy reaction, seek medical help immediately: difficulty breathing, hives or swelling around lips, face throat or tongue.

Famciclovir may cause serious side effects. If you experience:

  • Confusion;
  • Kidney problems include little or no urine, swelling of the feet and ankles, or feeling fatigued or short of breath.

Side effects common to famciclovir include:

  • Headache;
  • Nausea.

There may be other side effects.Call your physician immediately if experiencing side effects; report these to FDA by dialing their toll free number 1-800-FDA-1088.

Similar/related drugs

Prednisone, Acyclovir, Valacyclovir, Valtrex, Zovirax, Deltasone, and Tetracaine Topical


Please read and follow all instructions found on your medication package or label, inform doctors about allergies or medical conditions that require medication, as well as which drugs you take and their duration.

Before you take this drug

If you have an allergy to penciclovir (Denavir), then do not take famciclovir.

If you've ever:

  • Liver disease
  • Kidney disease
  • A weak immune system
  • Galactose intolerance;
  • Severe lactase deficiency;
  • Glucose-galactose malabsorption.

Informing your physician of your plan to become pregnant is critical if you suffer from genital lesions; taking medications as directed will help mitigate potential outbreaks during gestation. To control symptoms effectively and manage them safely. You may find your name on a registry for pregnant women to monitor the effects of famciclovir. Breast-feeding may be unsafe while taking this medication. You should consult your physician about possible risks. Famciclovir should not be used by those under the age of 18.

How to take Famciclovir?

Read all the instructions or guides that come with your medication and follow the directions. Sometimes, your doctor will change the dose. You must take the medication exactly as it is prescribed. This medicine will not be more effective if you take more than the prescribed amount of famciclovir. You should take famciclovir for cold sores and genital herpes as soon as you notice the symptoms. Take famciclovir either with food or without. Herpes virus lesions should be as dry and clean as possible. It may be helpful to wear loose clothes in order to avoid irritation. Take famciclovir for up to one year to prevent the recurrence of genital herpes. Please follow your doctor's advice. Even if you feel better quickly, continue to take this medication for the entire prescribed time. If you skip doses, your virus may become resistant to the medication. Keep away from heat and moisture at room temperature.

Details on dosage

Usual Adult Dose for Herpes Simplex—Mucocutaneous/Immunocompetent Host:
Herpes genitalis:
The US Centers for Disease Control and Prevention recommend taking 250mg orally three times a day for seven to ten days.
The CDC recommends 1000 mg twice a day for one day. Alternatively, take 125mg twice a day for five days.
Famciclovir is recommended at the first sign of an episode that recurs (such as tingling or burning sensations, itching, or pain). It hasn't been proven that if the medication is taken more than six hours after symptoms or lesions appear, it will be effective.
Usual Adult Dose for Herpes Simplex—Mucocutaneous/Immunocompromised Host:
Recurrent orolabial herpes or genital shingles in HIV-infected individuals: Take 500mg twice a day for seven days (the CDC recommends five to ten days).
Famciclovir is recommended to be taken at the first sign of an episode that occurs repeatedly (such as burning, tingling, or itching) or when a lesion or pain appears. It hasn't been proven that famciclovir is effective if taken for more than 48 hours following the onset of lesions or symptoms.
Adult dose for Herpes Simplex: suppression:
Herpes genitalis recurrent: chronic suppression
Patients with immune competence: Take 250mg orally, twice daily.
The CDC has recommended that HIV-infected individuals take 500mg orally, twice a week.
The safety and effectiveness of famciclovir treatment beyond one year have not been proven.
Adult dose for Herpes Zoster:
Take 500mg every 8 hours for seven days.
Famciclovir has the best effectiveness if taken within 48 hours after the onset of a skin rash. It hasn't been proven that if you start more than 72 hours following the onset of your rash, it will be effective.
Adult dose for Herpes Simplex LabialisHerpes labialis recurrent: Take 1500mg orally in a single dosage.
Famciclovir works best when taken at the first sign of cold sores (tingling, burning, or itching) or symptoms.

What happens if I miss the dose?

If you are almost due for the next dose, skip the missed one. Never take more than one dose at a time.

What happens if I overdose?

Call 1-800-222-1222 for poison help or seek immediate medical attention.

What should be avoided?

Famciclovir does not stop you from spreading genital herpes. Herpes is contagious, and it's possible to infect others while taking famciclovir. Do not drive or engage in hazardous activities until you have determined how the medicine affects you. You may be unable to react properly. Use a condom or avoid sexual contact to prevent the spread of this virus. Do not let infected parts of the body come into contact with other people. Do not touch an infected part of your body and then rub your eyes. Hands should be washed frequently to avoid the spread of infections.

Interaction with other drug

Other medications, such as vitamin and herb products, may also affect famciclovir. Inform your doctor of all the medicines you are taking and those that you stop or start using.



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