The shingles virus is caused by the varicella-zoster virus (VZV), the same virus responsible for chickenpox. After a person recovers from chickenpox, the virus remains dormant in the nerve cells and can reactivate later in life, especially when the immune system weakens. This reactivation leads to shingles (herpes zoster), a condition marked by pain, tingling, and a blistering rash on one side of the body or face. While it usually resolves in 2–4 weeks, complications like long-lasting nerve pain can occur. Vaccination, such as with Shingrix, can help prevent shingles or reduce its severity.