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Why is this medication prescribed?

Herpes zoster (shingles), a rash that can happen to persons who have previously had chickenpox, is treated with famciclovir. People with a healthy immune system can also take it to treat recurrent cases of fever blisters or cold sores caused by the herpes virus. In persons with a healthy immune system, famciclovir is used to treat recurrent outbreaks and prevent new ones of genital herpes, an infection with the herpes virus that occasionally causes sores to appear around the genitalia and rectum. In patients with human immunodeficiency virus (HIV) infection, famciclovir is also used to treat recurrent herpes simplex infections of the skin and mucous membranes (mouth, anus). The drug famciclovir belongs to the antiviral drug class. It functions by preventing the herpes virus from spreading throughout the body. Famciclovir does not treat herpes infections and might not be able to stop the virus from spreading to new victims. However, it may lessen the sensations of pain, burning, tingling, soreness, and itching; aid in the healing of existing sores; and stop the development of new sores.

How should this medicine be used?

Famciclovir is available as a tablet that can be taken orally with or without food. In order to effectively treat shingles, famciclovir is often given three times day, every eight hours, beginning three days after the first signs of the rash. Famciclovir is often used as a single dose at the first indication or symptom (tingling, itching, or burning) of a cold sore in order to treat cold sores and fever blisters. Famciclovir is often used twice daily for one day, beginning within six hours after the onset of the first sign or symptom of the condition, to treat recurrent outbreaks of genital herpes. Usually taken twice daily for up to a year, famciclovir prevents genital herpes from recurring. Famciclovir is often administered twice daily for seven days while treating herpes in HIV-positive patients. Ask your doctor or pharmacist to explain any instructions on your prescription label that you are unsure about following. Follow the prescription for famciclovir exactly. Never take it in larger or less amounts or more frequently than directed by your doctor. As soon as symptoms start, take this drug.

Famciclovir should be taken even if you feel OK. Without consulting your doctor, do not discontinue taking famciclovir.

Other uses for this medicine

Ask your doctor or pharmacist for more details if you believe this drug should be used for something else.

What special precautions should I follow?

Before taking famciclovir,

  • If you have any allergies, including to lactose, famciclovir, penciclovir cream (Denavir), acyclovir (Zovirax), or other drugs, let your doctor and pharmacist know right once.
  • Inform your doctor and pharmacist about all other drugs you are taking or intend to take, notably probenecid (Benemid) and other prescription and non-prescription drugs, vitamins, nutritional supplements, and herbal products.
  • Inform your doctor if you have or have ever had issues with your immune system, HIV infection or AIDS, glucose-galactose malabsorption (an inherited condition where the body is unable to absorb lactose), kidney or liver disease, or if you have any of these conditions.
  • Inform your doctor if you are expecting, intend to get pregnant, or are nursing a baby. Call your doctor if you become pregnant while taking famciclovir.
  • Famciclovir may cause you to feel sleepy, lightheaded, confused, or disoriented. Prior to understanding how this drug affects you, avoid using machinery or driving a car.

What special dietary instructions should I follow?

Keep eating normally unless your doctor instructs you otherwise.

What should I do if I forget a dose?

As soon as you remember to take it, take the missing dose; then, space out the remaining doses throughout the day. If the next dose is soon due, skip the missed one and carry on with your regular dosing plan. To make up for a missing dose, do not take a second one.

What side effects can this medication cause?

Famciclovir could have negative effects. If any of these signs, together with those in the SPECIAL PRECAUTIONS section above, are bothersome or persistent, consult a medical professional right away:

  • Headache
  • Nausea
  • Vomiting
  • Loose stools or diarrhea
  • Gas
  • Abdominal pain
  • Tiredness
  • Rash
  • Itching
  • Grueling menstrual cycles

Call your doctor right away if you suffer any of the following side effects:

  • Hands or foot pain, burning, numbness, or tingling

You or your doctor can submit a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online at or by phone at 1-800-332-1088 if you have a serious side event.

What should I know about storage and disposal of this medication?

Keep this medication tightly closed in the original container and out of the reach of children. Keep it at room temperature and out of the bathroom and other places with excessive heat and moisture.

As many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and are simple for young children to open, it is crucial to keep all medications out of sight and out of reach of children. Always lock safety caps and promptly stash medication up and away from young children where it is out of their sight and reach to prevent poisoning.

Unused prescriptions must be disposed of carefully to prevent pets, kids, and other people from ingesting them. You should not, however, dispose of this medication in the toilet. Instead, utilizing a medicine take-back program is the easiest approach to get rid of your medication. To find out about take-back programs in your area, speak with your pharmacist or the garbage/recycling department in your city. If you do not have access to a take-back program, see the FDA’s Safe Disposal of Medicines website at for additional information.

In case of emergency/overdose

Call the poison control hotline at 1-800-222-1222 in the event of an overdose. Additionally, information can be found online at Call 911 right once if the person has collapsed, experienced a seizure, is having difficulty breathing, or cannot be roused.

What other information should I know?

Maintain all scheduled times with your physician and the lab. To determine how you responded to famciclovir, your doctor may have you undergo a few lab tests.

When you are experiencing a genital herpes outbreak, avoid having sexual contact. Even if you don’t have any symptoms, genital herpes can still spread to other people.

No one else should take your medication. Any queries you may have regarding medication refills should be directed to your pharmacist. Call your doctor if you continue to experience infection symptoms after taking the famciclovir.

You should keep a written record of every medication you take, including any over-the-counter (OTC) items, prescription drugs, and dietary supplements like vitamins and minerals. This list should be brought with you whenever you see a doctor or are admitted to the hospital. You should always have this information with you in case of emergencies.

Brand names

  • Famvir®
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