What is the cause of shingles?

Zoster reactivation: Shingles (herpes zoster) is caused by reactivation of varicella zoster, the chickenpox virus, which lives in your nerve cells. It's painful, but if you have a healthy immune system it will get better on its own, and faster if you take anti-herpes drugs quickly. The main complication is post-herpetic neuralgia, chronic pain in the area of the lesions, which is more likely to occur in older people.