Shingles, also called herpes zoster, is a painful skin rash caused by reactivation of the varicella zoster virus. This virus is the same one that gives people chicken pox. After
a person recovers from chicken pox, the virus retreats to the body's nerves, where it can hibernate indefinitely. In about two out of every ten people, the virus eventually reactivates as shingles.
The reasons the varicella zoster virus reactivates as shingles include:
- An aging immune system (it's most common in adults over age 50).
- Medications that weaken immunity (including chemotherapy and medications given after transplants).
- Infections that weaken immunity (such as HIV).
Shingles usually starts with pain, for days or even weeks before a red rash appears. The pain and the rash are usually focused on just one side and one part of the body -- on the left or right side of the neck, for example. Within a few days the rash spots turn into blisters, which crust over within seven to ten days.
Shingles can be treated with antiviral medications, but this is usually only helpful if treatment is started within the first 72 hours after the rash appears.
You can't catch shingles from another person, the way you can catch chicken pox. But a person who hasn't had chicken pox can get the virus from someone with shingles -- although that's rare. For that reason, however, until blisters have healed, adults with the condition should stay away from unimmunized babies or pregnant women who haven't had either chicken pox or its vaccine.
Shingles can recur after you've had it once, but only rarely. The shingles vaccine makes it less likely that you'd develop shingles and can reduce its severity if you do get it. The vaccine is recommended for almost all adults over age 60, even those who have already had shingles.