Shingles (herpes zoster) is a viral infection caused by the varicella zoster virus, the same virus that causes chickenpox. It causes that causes a painful rash. Although shingles can occur anywhere on your body, it most often appears as a single stripe of blisters that wraps around either the left or the right side of your torso. After a person recovers from chickenpox, the virus stays in the body in a dormant (inactive) state. For reasons that are not fully known, the virus can reactivate years later, causing shingles. Herpes zoster is not caused by the same virus that causes genital herpes, a sexually transmitted disease.
Almost 1 out of every 3 people in the United States will develop shingles. Anyone who has ever had chickenpox may develop shingles.