Commonly tested allergens include inhaled allergens (pollen, molds, pet allergens, dust mites, cockroaches), foods, insects, and a few medications. Small amounts of a purified extract are applied to the skin using two methods:

• Prick-puncture testing is generally the first screen and is performed by "pricking" the skin on the back (or arm) with a small plastic applicator coated with the allergen.
• Intradermal testing is performed by injecting small amounts of the suspected allergen into the most superficial layer of skin.

If you have sensitivity to a specific allergen, a small wheal and flare (similar to a small mosquito bite) are seen within 15-20 minutes. This is measured by the technician performing the test.