Q. I'm suffering from a very painful case of shingles. My doctor prescribed a new medicine called Zostrix, which I apply four times a day for relief, but it just isn't working.

Is there any other treatment I can take? Is there a cure for shingles?

Will it spread? How long will it last? How did I get it in the first place?

A. Shingles is a flare-up of a nerve and skin infection caused by the varicella-zoster virus, the same virus that causes chickenpox.

Most people become infected with this virus during childhood. The virus then lies dormant in various nerves.

Sometimes because of lowered resistance and sometimes for no apparent reason, the virus later erupts into the painful red blistering skin rash known as shingles.

The outbreak of shingles is confined to the band of skin above the affected nerve. Ordinarily, shingles won't spread to other parts of the body and isn't contagious between most adults.

In most cases, the skin sores last a couple of weeks and the nerve pains up to a month or so. But, for a few shingles sufferers, the nerve pain can last indefinitely.

There's no cure for shingles, although two new treatments may help. One is using the anti-virus medicine acyclovir in high doses.

The good news is that it seems to speed healing and reduce pain.

The bad news is that it's expensive and doesn't seem to reliably prevent the persistence of nerve pain (neuralgia).

The other new treatment is the one you're using now. Zostrix is a topical cream designed to reduce nerve pain from shingles. It's derived from capsicum, the red peppers used to make chili powder and cayenne pepper. The main side effect is burning of the skin.

For persistent nerve pain, some doctors use the antidepressant medicine Elavil, anti-seizure medicines Dilantin and Tegretol or a combination of Elavil and Prolixin. These drugs may or may not help, because there's no sure treatment for this troublesome condition.

If medication doesn't give any relief, you might try getting an injection of an anesthetic into the affected nerve.

Jay Siwek, a family physician from Georgetown University, practices at the Fort Lincoln Family Medicine Center and Providence Hospital in Northeast Washington.

Consultation is a health education column and is not a substitute for medical advice from your physician.

Send questions to Consultation, Health Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Questions cannot be answered individually.