What happens during a rash evaluation?
There are different ways to do a rash evaluation. The type of test you get will depend on your symptoms and medical history.
To test for allergic contact dermatitis, your health care provider may give you a patch test:
During a patch test:
A provider will place small patches on your skin. The patches look like adhesive bandages. They contain small amounts of specific allergens (substances that cause an allergic reaction).
You'll wear the patches for 48 to 96 hours and then return to your provider's office.
Your provider will remove the patches and check for rashes or other reactions.
There is no test for irritant contact dermatitis. But your provider may make a diagnosis based on a physical exam, your symptoms, and information you provide about your exposure to certain substances.
A rash evaluation may also include a blood test and/or a skin biopsy.
During a blood test:
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out.
During a biopsy:
A provider will use a special tool or a blade to remove a small piece of skin for testing.
