The varicella zoster virus causes both chickenpox and shingles, according to WebMD. Shingles, also called herpes zoster, occurs when the varicella zoster virus becomes active after lying dormant in the nerve roots of a person who previously had chickenpox.
Some people who have had chickenpox never experience shingles; however, conditions such as age, stress or disease can weaken the immune system and allow reactivation of the varicella zoster virus, according to WebMD. The reactivation of the virus only causes shingles, not chickenpox. The main symptom of shingles is a painful skin rash occurring in a small strip or area on the face or body.