It is caused by a viral infection of the nerves that travel to certain areas of the skin. The second condition associated with shingles is pain that persists after the rash has healed. This condition is known as postherpetic neuralgia. It results from nerve damage done during the infection. For that matter, although the rash is usually painful, not everyone with shingles experiences severe pain from the rash.
Shingles is most common in older adults and the risk of developing it increases with age.
Another risk factor for developing shingles is suppression of the immune system. Some sort of drop in the immune system is the current hypothesis about what brings on herpes zoster, according to Dr. Bradley Galer, University of Washington assistant professor of anesthesia and neurology. The event that leads to an attack of herpes zoster is reactivation of the chicken pox virus. The virus, usually acquired in childhood, lies dormant in nerve cells along the spinal cord. After it is somehow triggered to reemerge, the virus grows along a nerve, damaging it and showing up on the skin surface as a painful rash of small, crusting blisters.