Drug Notes

Famciclovir (By mouth)

Famciclovir (fam-SYE-kloe-vir)

Treats herpes virus infections, including shingles, cold sores, and genital herpes. This medicine will not cure herpes, but may prevent a breakout of herpes sores or blisters.

Brand Name(s):

Famvir

When This Medicine Should Not Be Used:

How to Use This Medicine:

Tablet

• Your doctor will tell you how much medicine to use. Do not use more than directed.
• Take this medicine at the first sign of a herpes breakout or as soon as possible. The medicine might not work as well if you start treatment too late.
• Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
• Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
• Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Some medicines can affect how famciclovir works. Tell your doctor if you are using probenecid.

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, or lactose absorption problems.
• This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
• Famciclovir will not stop the spread of herpes during sex. Avoid having sex while you have herpes sores.
• Even if you have no signs of a herpes infection, it is still possible to spread the virus to others during sex. Talk with your doctor about ways to keep from spreading the virus.
• Call your doctor if your symptoms do not improve or if they get worse.
• Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Blistering, peeling, red skin rash
• Decrease in how much or how often you urinate
• Rapid weight gain, swelling of your face, ankles, or hands

If you notice these less serious side effects, talk with your doctor:

• Confusion, dizziness, sleepiness
• Headache

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 1/27/2017