Shingles (herpes zoster) is a viral infection caused by the varicella-zoster virus (VZV), the same virus that causes chicken pox. After a person has had chickenpox, VZV remains in a dormant (inactive) state in the nerve roots for the rest of their life. VZV may reactivate years later in the form of a painful skin rash known as shingles.  The disorder is relatively common, with more than 500,000 cases reported annually, according to the National Institute of Allergy and Infectious Diseases.

Why VZV becomes active after a prolonged period of dormancy is unknown. Research suggests that several factors may play a role in the development of shingles (e.g., weakened immune system, stress, fatigue).

A physician can often diagnose a shingles rash by physical examination. However, a physician may perform tests for confirmation (e.g., Tzank smear). Most cases of shingles go away without treatment. However, a physician may recommend some treatments to reduce pain and speed recovery.