The evaluation of chicken pox begins with a medical history and physical examination.

Physical findings in someone with chicken pox may include:

• A blistery skin rash
• Some lesions may occur inside the mouth

Testing is not necessary to diagnose chicken pox. Tests may be performed to evaluate the severity of the illness, or to detect pneumonia.

Tests that may be used to evaluate chicken pox include:

• Chest x-ray
• May show viral pneumonia
• Pulse oximetry
• Complete blood count
• Chicken pox titer:
• Blood test that measures antibodies to chicken pox virus