Percutaneous (prick) testing, intradermal testing  and Immunocap testing are the methods used to determine what allergens people are allergic to.

Percutaneous or prick testing is when the suspecting allergens are placed on the patients back and the skin is lightly scratched. After 15 minutes, the skin is checked for a local reaction. The size of the reaction is documented.

Intradermal testing is generally performed if all or certain parts of the Percutaneous test is negative. This process involves injecting a small amount of allergens under the first layer of the skin. As with Percutaneous testing, the skin is checked after 15 minutes.

RAST (radioallergosorbent) Immunocap testing is performed at a laboratory. With this process, a blood sample is sent to a laboratory and checked to see if the patient is making any allergen-specific antibodies. This type of testing is performed when a person has a skin condition or on medication which interferes with skin testing.