What causes shingles?

After chickenpox clears, the virus can stay quiet in sensory nerve tissue. Later, it may reactivate and travel along that nerve toward the skin, producing burning, tingling, sensitivity, or pain followed by a strip or cluster of blisters. Reactivation becomes more likely when immune protection is weakened, including with ageing, certain illnesses, or immune-suppressing medicines. Shingles is not a new chickenpox infection, although a person with active blisters can pass the virus to someone who has never had chickenpox or vaccination.

Contact a clinician as soon as a one-sided painful rash or grouped blisters appear, because antiviral treatment works best when started early. Keep the rash clean and covered, wash your hands, and avoid touching the eyes. Until lesions crust, avoid close contact with pregnant people who are not immune, newborns, and people with weakened immunity. Do not share towels or clothing.

Seek urgent medical advice for a rash near the eye or ear, facial weakness, severe headache, confusion, widespread blisters, or a weakened immune system. Prompt care is also sensible when pain is intense or the diagnosis is uncertain. Persistent nerve pain after the rash heals should be discussed with a clinician.

Could this rash be shingles rather than another blistering condition? Should I start antiviral medicine, and how should I protect people around me? What can help if nerve pain continues after the skin clears?