Famvir tablets are used to treat herpes zoster, commonly referred to as “shingles,” in adults. Shingles is a painful rash with raised, red pimples on the trunk of the body, usually the back. Because it is caused by the same virus that causes chickenpox, only people who have had chickenpox can get shingles. When prescribed for shingles, Famvir works best in people age 50 or over.
Famvir is also prescribed to treat attacks of genital herpes and to prevent future flare-ups. For people with HIV infections, it is used as a treatment for both genital and oral herpes.
Most important fact about Famvir
Famvir is most effective if started within the first 48 hours after shingles first appears; treatment should be started at the first sign or symptom of genital herpes. Famvir treatment may not be effective if it is delayed more than 72 hours after the herpes zoster rash first appears or more than 6 hours after genital herpes becomes evident. Thus, it is important to see your doctor as soon as possible after symptoms appear.
How should you take Famvir?
For maximum benefit, take Famvir for the full time of treatment, even if your symptoms begin to clear up. Do not, however, take Famvir more often or for a longer time than your doctor directs.
You may take Famvir with meals or in between.
If you miss a dose: Take the forgotten dose as soon as you remember. If it is almost time for your next dose, skip the one you missed and go back to your regular schedule. Never take two doses at the same time.
Storage instructions: Store at room temperature.
What side effects may occur?
Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Famvir.
- More common side effects may include:
Constipation, diarrhea, dizziness, fatigue, fever, headache, nausea, vomiting
Why should Famvir not be prescribed?
Do not take Famvir if you are sensitive to it or have ever had an allergic reaction to it. Also avoid Famvir if you are sensitive to Denavir (penciclovir cream).
Special warnings about Famvir
Famvir speeds healing of shingles and genital herpes, but it is not a cure. It may not prevent transmission of genital herpes to others, so you should avoid sexual intercourse whenever you have symptoms of the disease.
If you have any kidney problems, be sure your doctor knows about them before prescribing Famvir for you.
Possible food and drug interactions when taking Famvir
If Famvir is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Famvir with probenecid (Benemid), a drug used to treat gout (a type of arthritis).
Special information if you are pregnant or breastfeeding
The effects of Famvir during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, inform your doctor immediately. Famvir should be used during pregnancy only when the benefit to the mother clearly outweighs the potential risk to the baby. Famvir may appear in breast milk, and could affect a nursing infant. If Famvir is essential to your health, your doctor may advise you to discontinue breastfeeding until your treatment with Famvir is finished.
The usual adult dose is 500 milligrams every 8 hours for 7 days.
Recurrent Genital Herpes Treatment
The usual dose is 125 milligrams twice a day for 5 days.
Recurrent Genital Herpes Prevention
The usual dose is 250 milligrams twice a day for up to one year. Famvir therapy to prevent genital herpes has not been tested for periods exceeding one year.
Recurrent Oral or Genital Herpes in HIV-infected Individuals
The usual dose is 500 milligrams twice a day for 7 days. Smaller doses are prescribed for people with damaged kidneys.
Safety and effectiveness in children under the age of 18 have not been established.
Any medication taken in excess can have serious consequences. If you suspect an overdose, seek medical attention immediately.