What causes the pain of shingles?

Shingles pain occurs when dormant viral cells, lurking for years in nerve clusters called sensory ganglia, reactivate and travel down the nerves to the skin, states the National Institute of Neurological Disorders and Stroke. Along the way, the viral cells blaze a painful trail and may cause sensory loss.

Once the viral cells reach the skin, they multiply, causing the characteristic itchy rash associated with shingles, reports the National Institute of Neurological Disorders and Stroke. The viral cells enter the body following exposure to chicken pox, and as of 2014, the government does not know what causes them to reactivate. The pain and itching of shingles can linger after the infection is cured.