Herpes zoster, commonly called shingles or zona, is an illness caused by reactivation of the varicella‑zoster virus (VZV). The same virus produces chickenpox after primary infection in childhood; years later the latent virus can awaken and produce shingles (chickenpox link to primary infection).

Symptoms

The illness typically presents with localized pain followed by a rash that develops into grouped fluid‑filled blisters in a band corresponding to a single sensory nerve distribution (dermatome). Common early features are:

  • Pain, burning or tingling in one area of the skin
  • Rash that evolves to blisters and then crusts
  • Fever, headache and general malaise in some people
  • Possible eye involvement (herpes zoster ophthalmicus) or facial nerve involvement (Ramsay Hunt syndrome)

Cause and course

After an initial episode of chickenpox, VZV remains dormant in sensory ganglia. Reactivation—often decades later—causes viral replication in the nerve and painful skin lesions along its sensory distribution. Risk of reactivation rises with advancing age and weakened immunity, and stressful events or certain medical treatments can contribute.

Diagnosis and differential

Diagnosis is usually clinical, based on the characteristic unilateral, dermatomal rash and pain. Laboratory confirmation, when needed, can use PCR testing of lesion swabs, direct antigen detection, or viral culture. Conditions that can mimic shingles include contact dermatitis, herpes simplex, and other vesicular eruptions.

Treatment and prevention

Antiviral therapy (for example acyclovir, valacyclovir or famciclovir) is most effective when begun early—typically within the first 72 hours of rash onset—and can shorten duration and reduce complications. Pain management ranges from simple analgesics to neuropathic agents and topical measures; severe cases may require specialist input. The shingles vaccine reduces the risk of developing shingles and of severe outcomes; see vaccine information for guidance (vaccine).

Complications and prognosis

Most episodes resolve over weeks, but complications can include persistent nerve pain (postherpetic neuralgia), eye damage if the eye is involved, secondary bacterial infection of lesions, and less commonly neurologic sequelae. Prompt recognition, early antiviral therapy, and vaccination in eligible persons reduce the burden of disease.