In the U.S.—

In Canada—

• Antiviral, systemic

Famciclovir (fam-SYE-kloe-veer) is used to treat the symptoms of herpes zoster (also known as shingles), a herpes virus infection of the skin. It is used to treat and suppress recurrent episodes of genital herpes infection. This medicine is also used to treat recurrent herpes virus infections of the mucous membranes (lips and mouth) and genitals in HIV-infected patients. Although famciclovir will not cure genital herpes or herpes zoster, it does help relieve the pain and discomfort and helps the sores heal faster.

Famciclovir is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For famciclovir, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to famciclovir. Also tell your health care professional if you are allergic to any other substances, such as foods, sulfites or other preservatives, or dyes.

Pregnancy—Famciclovir has not been studied in pregnant women. However, famciclovir has not been shown to cause birth defects or other problems in animal studies.

Breast-feeding—It is not known whether famciclovir passes into the breast milk of humans; however, it does pass into the milk of rats. Famciclovir is not recommended during breast-feeding because it may cause unwanted effects in nursing babies.

Children—Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of famciclovir in children with use in other age groups.

Older adults—Famciclovir has been used in the elderly and has not been shown to cause different side effects or problems in older people than it does in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change your dose or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

• Kidney disease—Kidney disease may increase blood levels of this medicine, increasing the chance of side effects

Famciclovir is best used within 48 hours after the symptoms of shingles (for example, pain, burning, blisters) begin to appear, or within 6 hours after the symptoms of recurrent genital herpes (for example, pain, blisters) begin to appear.

Famciclovir may be taken with meals.

To help clear up your herpes infection, keep taking famciclovir for the full time of treatment, even if your symptoms begin to clear up after a few days. Do not miss any doses. However, do not use this medicine more often or for a longer time than your doctor ordered.

Dosing—

The dose of famciclovir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of famciclovir. Your dose may be different if you have kidney disease. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (tablets):
  • For treatment of shingles:
    • Adults—500 milligrams (mg) every eight hours for seven days.
    • Children—Use and dose must be determined by your doctor.
  • For suppression of recurrent genital herpes:
    • Adults—250 mg two times a day for up to one year.
    • Children—Use and dose must be determined by your doctor.
  • For treatment of recurrent genital herpes:
    • Adults—125 mg two times a day for five days.
    • Children—Use and dose must be determined by your doctor.
  • For treatment of recurrent herpes virus infections of the mucous membranes (lips and mouth) and genitals in HIV-infected patients:
    • Adults—500 mg two times a day for seven days.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the tablets in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

The areas affected by herpes should be kept as clean and dry as possible. Also, wear loose-fitting clothing to avoid irritating the sores (blisters).

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Headache 
  
  

• Less common
  • Diarrhea;  dizziness;  nausea;  unusual tiredness or weakness;  vomiting 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.