The varicella-zoster virus causes both chickenpox and shingles. After a chickenpox attack, the virus can lie dormant in the body for many years. Once reactivated, the virus quickly travels through nerve cells, causing rash and nerve pain. In 2006, scientists at the U.S. National Institutes of Health identified a specific protein that causes the virus to spread throughout cells in the body. Researchers hope that this important discovery may lead to new drug treatments for shingles.


Complications
For about one in five people who develop shingles, the pain continues in the same spot long after the blisters have cleared. This condition is known as postherpetic neuralgia.

When you have postherpetic neuralgia, damaged nerve fibers send confused and exaggerated messages of pain from your skin to your brain. This leaves the affected area of skin sensitive to even the slightest touch. For some people, the brush of clothing or a breeze can be excruciatingly painful.

Pain medication, antidepressants or anticonvulsant medications may help provide relief until the pain subsides.

Shingles can also lead to other complications, including inflammation of the brain (encephalitis) and other neurological problems. If shingles occurs on your face, it can cause hearing problems and temporary or permanent blindness. Loss of facial movement (paralysis) is possible as well. If blisters aren't properly treated, bacterial skin infections are another potential problem.