At some point in their lives, up to 20 percent of the population will be affected by shingles, which is officially known as herpes zoster and is caused by the varicella-zoster virus—the same virus that causes chickenpox. It attacks adults who had chickenpox as children but whose immune system has weakened due to aging, illness, drugs, radiation therapy, or physical or emotional stress. For many people shingles is a temporary condition, which starts at a nerve root and moves to the skin, causing a burning pain, rash, and blisters, all subsiding within a few weeks. But almost one-third of all cases are further afflicted with a painful complication called post-herpetic neuralgia, or PHN, which can continue for months or even years. Other potential complications of shingles include inflammation of the eye, which could lead to loss of vision.
