Herpes zoster is caused by reactivation of varicella-zoster virus that has been lying dormant in nerve ganglia since a past chickenpox infection. When the immune system weakens or is stressed, the virus can reactivate along a specific nerve and cause the typical one-sided painful rash.
Your risk of shingles increases with age, a weakened immune system, chronic diseases, and certain medications like chemotherapy or long-term steroids. People who have had chickenpox are at risk, and complications are more common in older adults and those with immune suppression.
The main treatment for herpes zoster is early antiviral therapy with drugs like acyclovir, valacyclovir, or famciclovir, ideally started within 72 hours of rash onset. Pain control with analgesics, nerve pain medicines, and soothing topical care is crucial, and some people need specific treatment for postherpetic neuralgia.