How it is administered

Famciclovir is taken by mouth in the form of tablets. The tablets come in strengths of 125 mg, 250 mg, and 500 mg. It can be taken with or without food. Dosing may vary depending on the condition being treated and the patient's kidney function.

How it works

Famciclovir is an antiviral medication that works by stopping the replication of certain viruses. After you take famciclovir, your body converts it into penciclovir, which is the active form. Penciclovir works by blocking the viral DNA polymerase enzyme, which is necessary for the virus to make copies of itself. This action helps to control infections caused by herpes viruses, such as herpes simplex (which causes cold sores and genital herpes) and varicella zoster (which causes shingles).

Famciclovir is not a cure for these viral infections, but it can help to reduce the severity and duration of symptoms, promote healing of sores, and decrease the risk of spreading the virus to others. It is most effective when started at the first sign of symptoms.

Who Should take it

Famciclovir is approved for use in adults with:

• Recurrent herpes labialis (cold sores)
• Recurrent genital herpes (both treatment of outbreaks and suppressive therapy)
• Herpes zoster (shingles)
• Recurrent orolabial or genital herpes in HIV-infected adults

It may be prescribed to immunocompromised patients for the treatment of certain herpes virus infections, but its use in immunocompromised patients (other than HIV-infected adults) has not been fully established. It is not a cure, but it helps manage symptoms and reduce outbreaks.

Who should not take it

You should not take famciclovir if you have had an allergic reaction to famciclovir, penciclovir (the active form), or any of the ingredients in the tablet. It is also contraindicated if you are allergic to Denavir® (penciclovir cream).

People with severe kidney problems may require a dose adjustment, and those with rare hereditary problems of galactose intolerance, severe lactase deficiency, or glucose-galactose malabsorption should discuss with their healthcare provider before taking famciclovir. Always inform your doctor about all your allergies and medical conditions before starting this medication.

Commonly used with

Famciclovir is sometimes used alongside other antiviral medications, especially in people with weakened immune systems, such as those with HIV. It may also be used with medications to manage symptoms like pain or fever, such as acetaminophen or ibuprofen.

There are no significant interactions with most common medications, but always inform your doctor about all medicines you are taking.

Commonly tested with

Famciclovir has been compared in studies with other antiviral medications such as acyclovir and valacyclovir for the treatment of herpes virus infections. In HIV-infected patients, it has been tested alongside acyclovir to compare effectiveness and safety.

Routine blood tests may be performed to monitor kidney function, especially in patients at risk for kidney problems.