Pain expert Dr. Scott Fishman answers questions about nerve pain:

Q: What causes shingles and what is the best treatment?

A: Shingles arises from the chicken pox virus. It is a member of the herpes virus family but not the same one that causes genital herpes and other herpes infections. If you've had chicken pox, you have the virus for life, even though it is usually dormant and inactive.

The virus never leaves the body but lives quietly in your sensory nerves until some stress to the system brings it out of hiding. A telltale sign of shingles is a characteristic skin rash, indicating inflammation and nerves set off by the underlying virus.

Shingles can erupt because of a temporary letdown in the immune system from another illness such as cancer, AIDS, or even from decreased immune function related to normal aging. It is believed that it even can arise from temporary diminished immune function related to stress over work, family matters, late nights, or an alcohol binge. Medications such as corticosteroids or chemotherapy also can compromise the immune system and invite a shingles attack. Aging seems to make people more vulnerable, and shingles most often appears in people over fifty.

For an acute attack of shingles, treatment is a two-front assault: deactivating the virus and quieting overexcited nerves. The antiviral drug acyclovir shortens the duration of the symptoms as it weakens the re-awakened virus. An anti-convulsant drug such as gabapentin (trade name Neurontin) helps turn off the busy nerves that are causing the pain while analgesics like Tylenol, ibuprofen, or aspirin help smooth the rough edges of the discomfort.

At the end of a shingles attack, when everything is healing, patients may feel extremely unpleasant itching. The itch is probably from sickly nerves not yet fully healed. I have found that a cream called capsaicin works well on this itch. This cream is made from hot peppers and halts pain by depleting the skin of the chemicals that fuel pain. Without these chemicals, the nerves in the skin cannot transmit pain or itch signals.

It is important to treat shingles quickly and aggressively; otherwise, it can develop into an even more unpleasant condition called postherpetic neuralgia. While shingles usually involves a temporary localized burning sensation and hypersensitivity, postherpetic neuralgia is much more chronic and can develop into intractable pain that can plague a person for months and years.