Shingles (herpes zoster) results from a reactivation of the virus that also causes chickenpox. With shingles, the first thing you may notice is a tingling sensation or pain on one side of your body or face. Painful skin blisters then erupt on only one side of your face or body along the distribution of nerves on the skin. Typically, this occurs along your chest, abdomen, back, or face, but it may also affect your neck, limbs, or lower back. The area can be very painful, itchy, and tender. After one to two weeks, the blisters heal and form scabs, although the pain often continues.
The deep pain that follows after the infection has run its course is known as postherpetic neuralgia. It can continue for months or even years, especially in older people. The incidence of shingles and of postherpetic neuralgia rises with increasing age. More than 50% of cases occur in people over 60. Shingles usually occurs only once, although it has been known to recur in some people.
Shingles arises from varicella-zoster, the same virus that causes chickenpox. Following a bout of chickenpox, the virus lies dormant in the spinal nerve cells. But it can be reactivated years later when the immune system is suppressed by:
Physical or emotional trauma
A serious illness
Medical science doesn't understand why the virus becomes reactivated in some people and not in others.