Shingles is a viral infection 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.

Shingles is caused by the varicella-zoster virus — the same virus that causes chickenpox. After you’ve had chickenpox, the virus lies inactive in nerve tissue near your spinal cord and brain. Years later, the virus may reactivate as shingles.

Shingles isn’t a life-threatening condition, but it can be very painful. Vaccines can help reduce the risk of shingles. Early treatment can help shorten a shingles infection and lessen the chance of complications. The most common complication is postherpetic neuralgia, which causes shingles pain for a long time after your blisters have cleared.