Smallpox and chickenpox both cause blisters that damage the skin. However, the rash in chickenpox appears in clusters on the face, abdomen, back, and scattered on the arms. Smallpox is concentrated in the arms and legs.

Shingles is a reactivation of the varicella zoster virus, the causative agent of chickenpox. The typical symptom of the disease is a rash in the form of small blisters on the chest, abdomen, one side of the body or face, causing pain to the patient. Although the risk of affecting the fetus when the mother has shingles is very low, pregnant women still need to be diagnosed and treated early to limit complications.

Shingles occurs in people with a history of chickenpox. After recovering from chickenpox, the virus lies dormant in nerve tissue near the spinal cord and brain, waiting for the immune system to weaken and trigger shingles.