Diagnosis

To diagnose dermatitis, your doctor will likely talk with you about your symptoms and examine your skin. You may need to have a small piece of skin removed (biopsied) for study in a lab, which helps rule out other conditions.

Patch testing

Your doctor may recommend patch testing on your skin. In this test, small amounts of different substances are applied to your skin and then covered. The doctor looks at your skin during visits over the next few days to look for signs of a reaction. Patch testing can help diagnose specific types of allergies causing your dermatitis.