What are shingles (herpes zoster)?

Shingles (herpes zoster) is characterized by a painful skin rash that occurs from the reactivation of the chickenpox virus (varicella-zoster). Most children are infected with the varicella-zoster virus, which lies dormant in the spinal nerves. Exposure to the virus boosts adult immunity so that reactivation usually occurs only if the immune system is suppressed. Shingles usually affects older adults with weakening immune systems or in immunosuppressed patients, but can occur at an age.