Shingles (herpes zoster)

Shingles is caused by the varicella-zoster virus — the same virus that causes chickenpox. After a childhood chickenpox infection, the virus does not leave the body but lies dormant in nerve roots. Years or decades later, often when the immune system is stressed, older, or weakened, it can reactivate and travel down a nerve to the skin, producing shingles. The hallmark is a painful, often burning or tingling rash that appears in a band or strip on one side of the body or face, following the path of the affected nerve — usually not crossing the midline. The pain often precedes the rash by a day or two; the rash then blisters and crusts over one to two weeks. It is diagnosed clinically from this characteristic appearance, so blood tests are not usually needed. The most important complication is post-herpetic neuralgia — nerve pain that lingers for months after the rash heals — which becomes more likely with age. Shingles affecting the eye or ear needs urgent specialist care. Antiviral medicines started early shorten the illness and reduce complications, and a vaccine is recommended for older adults to prevent it.

• Usually none — shingles is diagnosed clinically from the characteristic one-sided, band-like blistering rash.
• Viral swab/PCR of a blister — occasionally used if the diagnosis is unclear.
• Tests are directed at any underlying cause of a weakened immune system if shingles is severe, recurrent or in a young person.

• Pain, burning or tingling in one area of skin, often before any rash
• A rash in a band or strip on one side of the body or face
• Fluid-filled blisters that crust over in one to two weeks
• The rash usually does not cross the midline of the body
• Sometimes fever, headache and feeling unwell
• Lingering nerve pain after the rash heals (post-herpetic neuralgia)
• Eye or ear involvement — a warning needing urgent care