Overview: Famciclovir is an antiviral medicine that is used to treat conditions caused by herpes viruses, such as cold sores, genital herpes, and shingles. Famciclovir should be taken as soon as possible when you first have symptoms, such as burning, itching, or tingling. Common side effects include headache and nausea.
Uses
What is famciclovir used for?
Famciclovir is commonly used for the following conditions caused by herpes viruses.
Famciclovir may also be used for other conditions as determined by your healthcare provider.
How does famciclovir work (mechanism of action)?
Famciclovir is an antiviral medicine that stops the growth of herpes viruses and improves symptoms. It is important to note that famciclovir is not a cure. Herpes viruses stay in the body even if you do not have symptoms.
How is famciclovir supplied (dosage forms)?
Brands and other names
- Famvir
Dosage forms and strengths
- 125 mg oral tablets
- 250 mg oral tablets
- 500 mg oral tablets
How should I store famciclovir?
Famciclovir should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.
Side Effects
What are the most common side effects of famciclovir?
The most common side effects of famciclovir are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Headache
- Nausea
There may be other side effects of famciclovir that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of famciclovir?
While less common, the most serious side effects of famciclovir are described below, along with what to do if they happen.
Severe Allergic Reactions. Famciclovir may cause allergic reactions, which can be serious. Stop taking famciclovir and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching, skin rash, or pale red bumps on the skin called hives
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Warnings & Precautions
Who should not use famciclovir?
Allergies to Ingredients. People who are allergic to any of the following should not take famciclovir.
- Famciclovir
- Famvir
- Denavir
- Penciclovir
- Any of the ingredients in the specific product dispensed, which may include lactose
Your pharmacist can tell you all of the ingredients in the specific famciclovir products they stock.
What should I know about famciclovir before using it?
Do not take famciclovir unless it has been prescribed to you by a healthcare provider. Take it as prescribed.
Do not share famciclovir with other people, even if they have the same condition as you. It may harm them.
Keep famciclovir out of the reach of children.
Take famciclovir as soon as possible when you first have symptoms, such as burning, itching, or tingling.
Genital herpes can be passed to others during sexual activity even if you have no signs or symptoms. Ask your healthcare provider about safe sex practices, such as condoms. If you have symptoms or open sores from genital herpes, do not have sexual contact to avoid spreading it to others.
If you have drowsiness, dizziness, or confusion while taking famciclovir, do not drive or do other activities that require alertness or coordination.
What should I tell my healthcare provider before using famciclovir?
Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if famciclovir is right for you.
In particular, make sure that you discuss any of the following.
Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.
- Kidney problems
- Liver problems
- A weak immune system, including from HIV or AIDS
- A rare genetic problem of not being able to tolerate galactose, having a severe lactase deficiency, or if you cannot absorb glucose and galactose
Other Medicines and Supplements. Famciclovir may interact with other medicines and supplements. Before taking famciclovir, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
Vaccines. You may not be able to receive certain vaccines, such as the chickenpox (varicella) vaccine, right before or while taking famciclovir. Tell your healthcare provider about any vaccines you have recently received or have scheduled.
Pregnancy. It is not known if or how famciclovir could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take famciclovir while you are pregnant or trying to get pregnant.
Breastfeeding. It is not known if famciclovir passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take famciclovir while breastfeeding.
Interactions
Does famciclovir interact with foods or drinks?
There are no known interactions between famciclovir and foods or drinks.
There are no known interactions between famciclovir and alcohol, but heavy drinking can slow your immune response and make it harder for your body to fight infection.
Does famciclovir interact with other medicines (drug interactions)?
Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are taking probenecid, which is a medicine commonly used for gout, before taking famciclovir.
This may not be a complete list of medicines that can interact with famciclovir. Always check with your healthcare provider.
Overdose/Missed Dose
What should I do if I accidentally use too much famciclovir?
If you or someone else has used too much famciclovir, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
What should I do if I miss a dose of famciclovir?
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.
Are you currently using Famciclovir (Famvir)?
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