Anyone who has ever had chickenpox can develop shingles. Most adults in the United States had chickenpox when they were children, before the advent of the routine childhood vaccination that now protects against chickenpox.
•Being older than 50: Shingles is most common in people older than 50. The risk increases with age.
•Having certain diseases: Diseases that weaken your immune system, such as HIV/AIDS and cancer, can increase your risk of shingles.
•Undergoing cancer treatments: Radiation or chemotherapy can lower your resistance to diseases and may trigger shingles.
•Taking certain medications: Drugs designed to prevent rejection of transplanted organs can increase your risk of shingles — as can prolonged use of steroids, such as prednisone.
Complications:
•Postherpetic neuralgia: For some people, shingles pain continues long after the blisters have cleared. This condition is known as postherpetic neuralgia, and it occurs when damaged nerve fibers send confused and exaggerated messages of pain from your skin to your brain.
•Vision loss: Shingles in or around an eye (ophthalmic shingles) can cause painful eye infections that may result in vision loss.
•Neurological problems: Depending on which nerves are affected, shingles can cause an inflammation of the brain (encephalitis), facial paralysis, or hearing or balance problems.
•Skin infections: If shingles blisters aren't properly treated, bacterial skin infections may develop.
Courtesy: Mayo Clinic