Famciclovir, Oral

What are other names for this medicine?

Type of medicine: antiviral

Generic and brand names: famciclovir, oral; Famvir

What is this medicine used for?

This medicine is taken by mouth to prevent or treat certain viral infections such as cold sores, genital herpes, and shingles. It does not cure herpes.

It may be used for other conditions as determined by your healthcare provider.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

• an allergic reaction to any medicine
• a weakened immune system (caused by chemotherapy, HIV/AIDS, or a recent bone marrow or organ transplant
• kidney problems
• lactose intolerance, lactase deficiency, or problems with lactose absorption. This medicine contains lactose.
• liver disease

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. Do not breast-feed while taking this medicine without your healthcare provider's approval.

How should I take it?

Take this medicine exactly as your healthcare provider prescribes. Do not take more or less or take it longer than prescribed. Do not stop taking this medicine without your healthcare provider's approval. If you stop too soon the infection may return.

Start taking this medicine as soon as you notice a rash, sores, or pain. The sooner you start taking the medicine, the more effective the treatment is.

You may take this medicine with or without food. Taking it with meals may lessen the chance the drug will upset your stomach. Drink lots of water while you are taking this medicine.

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What should I watch out for?

This medicine is not a cure for herpes. Genital herpes is spread by sexual intercourse. Use a condom while sores are present. Check with your healthcare provider about what precautions to take.

Waiting too long after a rash appears to start taking this medicine may make it less effective.

If the rash and pain have not improved or get worse after 7 days of taking this medicine, contact your healthcare provider.

Do not take this medicine for any other skin condition unless directed by your healthcare provider.

Adults over the age of 65 may be at greater risk for side effects. Talk with your healthcare provider about this.

This medicine may make you dizzy or drowsy. Do not drive or operate machinery unless you are fully alert.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat), seizures (convulsions).

Serious (contact your healthcare provider right away): Numbness or tingling in hands or feet; unusual bruising or bleeding; black or tarry stools; leg pain; sore throat; rash; change in the amount of urine; unexplained fever; severe confusion; unusual weakness.

Other: Diarrhea, drowsiness, dizziness, headache, nausea, vomiting, acne, trouble sleeping, constipation, itching, fatigue.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• probenecid

Keep a list of all your medicines (prescription, nonprescription, supplements, natural remedies, and vitamins) with you. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.