Famciclovir (patient information)

Why this medication is prescribed

Famciclovir is used to treat herpes zoster (shingles) and genital herpes. It does not cure herpes infections but decreases pain and itching, helps sores to heal, and prevents new ones from forming.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

How this medication should be used

Famciclovir comes as a tablet to take by mouth. It is usually taken every 8 hours (three times a day) for 7 days to treat shingles. To treat genital herpes it is usually taken twice a day for 5 days. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take famciclovir exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. Use this medication as soon as possible after symptoms appear.

Continue to take famciclovir even if you feel well. Do not stop taking famciclovir without talking to your doctor.

Special precautions

Before taking famciclovir:

• tell your doctor and pharmacist if you are allergic to famciclovir, acyclovir (Zovirax), or any other drugs.
• tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially digoxin (Lanoxin), probenecid (Benemid), and vitamins.
• tell your doctor if you have or have ever had kidney or liver disease, problems with your immune system, human immunodeficiency virus infection (HIV), or acquired immunodeficiency syndrome (AIDS).
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking famciclovir, call your doctor.

Special dietary instructions

Famciclovir may cause an upset stomach. Take famciclovir with food or milk.

What to do if you forget a dose

Take the missed dose as soon as you remember it, and take any remaining doses for that day at evenly spaced intervals. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Side effects

Minor side effects

Famciclovir may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• headache
• upset stomach
• vomiting
• diarrhea or loose stools

Severe side effects

If you experience any of the following side effects, call your doctor immediately:

• rash
• itching

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at http://www.fda.gov/MedWatch/report.htm] or by phone [1-800-332-1088].

Storage conditions needed for this medication

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Other information

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to famciclovir.

Do not have sexual intercourse when you can see the genital herpes lesions. However, genital herpes can be spread even when there are no symptoms.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription. If you still have symptoms of infection after you finish the famciclovir, call your doctor.

Brand names

• Famvir®