Chickenpox and shingles are caused by the same virus, the varicella-zoster virus. Anyone who’s had chickenpox may develop shingles. After you recover from chickenpox, the virus can enter your nervous system and lie dormant for years.
Eventually, it may reactivate and travel along nerve pathways to your skin — producing shingles. But, not everyone who’s had chickenpox will develop shingles. Shingles usually occur in people with lower immunity to infections. Factors that may increase your risk of developing shingles include:
- Being older than 50. Shingles is most common in people older than 50. The risk increases with age. Some experts estimate that half the people age 80 and older will have shingles.
- 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.
Shingles is contagious, when a healthy person contacts the open sore of another’s shingles rashes, the healthy person may be infected. However, the person will then develop chickenpox rather than shingles, if he or she isn’t immune to chickenpox.