Famciclovir (Famvir) is a prescription drug used to treat herpes infections caused by the herpes zoster virus (shingles) and herpes simplex virus (cold sores and genital herpes). It is prescribed to treat outbreaks and for long-term suppressive therapy of herpes.
Famvir is the branded version of the drug produced by Novartis Pharmaceuticals. Generic Famvir is widely available.
The recommended dosage of famciclovir depends on the type and severity of the infection.
For genital herpes, adults are usually recommended to take 250 mg 3 times a day for 5 days. It’s best to take Famvir as soon as you notice signs of genital herpes such as sores around your genitals.
To suppress genital herpes, 250 mg of famciclovir can be taken 2 times a day for a maximum of 12 months.
If you have cold sores around your mouth, you should take a single dose of 1.5 g of Famvir.
For patients diagnosed with herpes zoster, a dose of 500 mg 3 times a day for 7 days is recommended.
It’s best to follow your doctor’s advice on how to take famciclovir.
Famciclovir is also used to treat cats. The following side effects relate to humans only.
Famvir is generally safe, but patients may experience some or all of the following mild side effects:
If you experience any of the following side effects, consult a doctor as soon as possible:
Although more severe side effects are rare, call emergency medical help in case you experience any of the following symptoms, as they could be signs of an allergic reaction:
A study of 455 patients with genital herpes found that suppressive therapy with famciclovir over 1 year was well-tolerated. Therefore, long-term therapy with famciclovir appears to be safe, but additional clinical trials are needed to verify these findings.
The following drugs are known to interact with Famvir (famciclovir):
It’s best to avoid drinking alcohol while taking famciclovir. Alcohol can worsen the side effects of famciclovir and make you feel dizzier or more nauseous.
Alcohol is also an immunosuppressant which means it negatively affects the immune system. This could make your antiviral therapy less effective and it may take longer to treat a herpes or shingles outbreak.