Famciclovir

WHY is this medicine prescribed?

Famciclovir is used to treat herpes zoster (shingles; a rash that can occur in people who have had chickenpox in the past). It is also used to treat repeat outbreaks of herpes virus cold sores or fever blisters in people with a normal immune system. Famciclovir is used to treat repeat outbreaks and to prevent further outbreaks of genital herpes (a herpes virus infection that causes sores to form around the genitals and rectum from time to time) in people with a normal immune system. Famciclovir is also used to treat returning herpes simplex infections of the skin and mucus membranes (mouth, anus) in people with human immunodeficiency virus (HIV) infection. Famciclovir is in a class of medications called antivirals. It works by stopping the spread of the herpes virus in the body. Famciclovir does not cure herpes infections and may not stop the spread of herpes virus to other people. However, it may decrease the symptoms of pain, burning, tingling, tenderness, and itching; help sores to heal; and prevent new sores from forming.

HOW should this medicine be used?

Famciclovir comes as a tablet to take by mouth with or without food. When famciclovir is used to treat shingles, it is usually taken every 8 hours (three times a day) for 7 days, starting within 3 days after the rash begins to appear. When famciclovir is used to treat cold sores and fever blisters, it is usually taken as one dose at the earliest sign or symptom (tingling, itching, or burning) of a cold sore. When famciclovir is used to treat repeat outbreaks of genital herpes, it is usually taken twice a day for one day, starting within 6 hours of the first sign or symptom of the condition. To keep genital herpes from returning, famciclovir is usually taken twice a day for up to 1 year. When famciclovir is used to treat herpes infection in people infected with HIV, it is usually taken twice a day for 7 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.

Are there OTHER USES for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What SPECIAL PRECAUTIONS should I follow?

Before taking famciclovir,

• tell your doctor and pharmacist if you are allergic to famciclovir, penciclovir cream (Denavir), acyclovir (Zovirax), any other medications, or lactose.
• tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take while taking famciclovir. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
• tell your doctor if you have or have ever had problems with your immune system, human immunodeficiency virus infection (HIV), or acquired immunodeficiency syndrome (AIDS); galactose intolerance or glucose-galactose malabsorption (inherited conditions where the body is not able to tolerate lactose); or kidney or liver disease.
• 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.
• you should know that famciclovir may make you drowsy, dizzy, confused, or disoriented. Do not drive a car or operate machinery until you know how this medication affects you.

What SPECIAL DIETARY instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do IF I FORGET to take 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.

What SIDE EFFECTS can this medicine cause?

Famciclovir may cause side effects. Tell your doctor if any of these symptoms or those listed in the SPECIAL PRECAUTIONS section above are severe or do not go away:

• headache
• nausea
• vomiting
• diarrhea or loose stools
• gas
• stomach pain
• tiredness
• rash
• itching
• painful menstrual periods

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

• pain, burning, numbness, or tingling in the hands or feet

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 (https://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

What should I know about STORAGE and DISPOSAL of 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).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. https://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (https://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

What should I do in case of OVERDOSE?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What OTHER INFORMATION should I know?

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

Do not have sexual intercourse when you are having an outbreak of genital herpes. However, genital herpes can be spread to others, even when you do not have 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.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

This report on medications is for your information only, and is not considered individual patient advice. Because of the changing nature of drug information, please consult your physician or pharmacist about specific clinical use.

The American Society of Health-System Pharmacists, Inc. represents that the information provided hereunder was formulated with a reasonable standard of care, and in conformity with professional standards in the field. The American Society of Health-System Pharmacists, Inc. makes no representations or warranties, express or implied, including, but not limited to, any implied warranty of merchantability and/or fitness for a particular purpose, with respect to such information and specifically disclaims all such warranties. Users are advised that decisions regarding drug therapy are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and the information is provided for informational purposes only. The entire monograph for a drug should be reviewed for a thorough understanding of the drug's actions, uses and side effects. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information is not a substitute for medical care.

AHFS^® Patient Medication Information™. © Copyright, 2024. The American Society of Health-System Pharmacists^®, 4500 East-West Highway, Suite 900, Bethesda, Maryland. All Rights Reserved. Duplication for commercial use must be authorized by ASHP.

Selected Revisions: December 15, 2017.