The National Institute of Health lists these possible complications:
- Newborns are at risk for severe infection, if they are exposed and their mothers are not immune.
- Women who get chickenpox during pregnancy are at risk for congenital infection of the fetus.
- A secondary infection of the blisters may occur.
- Encephalitis is a serious, but rare complication.
- Reye's syndrome, pneumonia, myocarditis, and transient arthritis are other possible complications of chickenpox.
- Cerebellar ataxia may appear during the recovery phase or later. This is characterized by a very unsteady walk.