The condition caused by reactivation of the varicella-zoster virus is shingles, also called herpes zoster.
The virus first causes chickenpox, usually during childhood. After the illness resolves, varicella-zoster virus remains dormant in nerve cells near the spinal cord or in cranial nerve ganglia. Years or decades later, it can reactivate and travel along a sensory nerve to the skin, producing a painful, localized rash.
Shingles commonly appears as blisters in a band on one side of the body or face. Pain, tingling, or burning can begin several days before the rash. Older age and weakened immunity increase the risk because immune control of the dormant virus can decline. A person with shingles can transmit the virus through contact with blister fluid, but a susceptible person develops chickenpox—not shingles—from that exposure.
A frequent mix-up is confusing shingles with cold sores: both involve herpes-family viruses, but cold sores are usually caused by herpes simplex virus. A major complication of shingles is postherpetic neuralgia, in which nerve pain persists after the rash heals.