Shingles, or herpes zoster, is a painful rash of blisters that develops due to the virus that causes chickenpox.

What is going on in the body?

A primary, or first time, infection with a virus called the varicella-zoster virus causes chickenpox. After someone recovers from chickenpox, the virus remains quiet, or dormant, in nerves. The infection can reactivate for various reasons later in life and this is called shingles.

What are the causes and risks of the infection?

The cause of this condition is a reactivation of the chickenpox virus. Most people in the US are infected with this virus. Weakness of the immune system may increase the risk of developing shingles. In people with weakened immune systems, infection can be very serious. In these people, the virus can spread all over the body, causing infection in the liver, lungs, and brain.