How It Works
Antiviral medicines prevent the virus
shingles from multiplying. These medicines shorten the
period of rash, reduce pain during the active stage of the illness, and
reduce the chance of getting complications of shingles, such as
postherpetic neuralgia. Antivirals may be taken orally
(by mouth) or injected intravenously (in a vein).
Why It Is Used
Anyone who has shingles can use
antivirals, but antivirals are particularly beneficial for adults older than 50
and people who have weak
immune systems. They are also used for people who have
severe rash and those who have rash near an eye and/or on the forehead.
How Well It Works
Antivirals may reduce the severity
of shingles and speed healing. When acyclovir, famciclovir, or valacyclovir are
taken within 3 days of getting shingles, these medicines can significantly
reduce the duration of pain associated with shingles. These medicines also
reduce the pain caused by postherpetic neuralgia.1
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
- Usually the benefits of the medicine are more important than any minor side effects.
- Side effects may go away after you take the medicine for a while.
- If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.
Call911or other emergency services right away if you have:
Call your doctor right away if you have:
Common side effects of this medicine include:
See Drug Reference
for a full list of side effects. (Drug Reference is not available in all
What To Think About
If you have kidney problems, you
may need to take less than the typical dosage of antiviral medicine. Before you
start antiviral treatment, be sure your doctor is aware of your other medical
Topical antivirals (antiviral medicines put
on the skin) do not help treat shingles.
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
Advice for women
If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Schmader KE, Oxman MN (2012). Varicella and herpes zoster. In LA Goldman et al., eds., Fitzpatrick's Dermatology in General Medicine, 8th ed., vol. 2, pp. 2383–2401. New York: McGraw-Hill.
Primary Medical Reviewer
||E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer
||Christine Hahn, MD - Epidemiology
Current as of
||December 18, 2012