A reactivation of the chickenpox virus in the body, causing a painful rash. Anyone who’s had chickenpox may develop shingles. It isn’t known what reactivates the virus.Shingles causes a painful rash that may appear as a stripe of blisters on the trunk of the body. Pain can persist even after the rash is gone (this is called postherpetic neuralgia).Treatments include pain relief and antiviral medications such as acyclovir or valacyclovir. A chickenpox vaccine in childhood or a shingles vaccine as an adult can minimize the risk of developing shingles.