DEAR MAYO CLINIC: I've had three bouts of shingles that have caused me pain. How do I prevent additional attacks?

ANSWER: Recurrent bouts of shingles are often associated with immune system problems that occur with aging or as a result of a medical condition or treatment. One of the best ways to prevent future attacks is to get the shingles vaccine. Unfortunately, many of the medical conditions and treatments that predispose you to shingles also prevent you from getting the vaccine. If removing the factors that are suppressing your immune system isn't possible, early treatment is often the best response to recurrent shingles. In severe or frequent cases, ongoing medication to reduce the risk of shingles may be an option.

Shingles is caused by the varicella-zoster virus, the same virus that causes chickenpox. Once you've had chickenpox, varicella-zoster stays in your body for the rest of your life. The virus can be reactivated at any time, resulting in shingles. Because those who have had chicken pox have some immunity against the virus, rather than getting a whole body rash again, you get a rash just in the areas supplied by the nerve where the virus is activated.

Shingles typically involves a band-like rash on the chest, back or face. The rash is usually quite painful. Most people recover from shingles in a few days, but a small number go on to develop severe pain along the nerve that was irritated when the virus came back. This lingering pain (postherpetic neuralgia) may last for weeks to months after the shingles episode, and it can be severe and very difficult to treat.

Reactivation of varicella-zoster virus and resultant shingles happens when your immune system is weakened by medications such as cancer treatments, steroids or simply by aging. Shingles is most common in people older than 50, and the risk of shingles continues to increase as people age. Some experts estimate that half the people who live to age 85 will experience shingles at some point in their lives. A shingles vaccine is available to help prevent the disorder and reduce the likelihood of recurrent shingles. The U.S. Centers for Disease Control and Prevention (CDC) recommends that all adults age 60 and older who have had chickenpox get the shingles vaccine.

Although people with weakened immune systems are at highest risk for developing shingles, the vaccine, unfortunately, is often not an option for them, as it is a live vaccine and hence not safe for people with weakened immune systems.

If you cannot receive the shingles vaccine, the best option for dealing with recurrent shingles is to treat each episode with prescription antiviral medication and pain medication as soon as possible. If you take antivirals within 48 hours of the rash appearing, the chances that you will develop postherpetic neuralgia are much lower. Your rash will also heal faster, and there will be less scarring and less pain associated with the rash.

If your immunosuppression is severe and the shingles episodes are frequent, talk to your doctor about the possibility of taking antiviral medication daily for a time. In some cases, this may help suppress subsequent episodes of shingles.

-- Priya Sampathkumar, M.D., Infectious Diseases, Mayo Clinic, Rochester, Minn.

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