Herpes zoster or shingles on the stomach region of a man. They show here as patchy clusters of small vesicles on a deep red background. The rash is very itchy and associated with pain which may persist months after the blisters have crusted and healed (post-herpetic neuralgia). Shingles is caused by the varicella zoster virus, which also causes chickenpox. During an attack of chickenpox, most of the viruses are destroyed, but some survive in the sensory nerve root of an area of skin. A weakened immune system allows the virus to re-emerge later, causing shingles. Treatment is with antivirals and painkillers.