Here is how both skin prick and intradermal tests are administered:
Prick/puncture. A diluted allergen is applied with a prick or a puncture on the surface of the skin.
Intradermal. Using a 26- to 30-gauge (very thin) needle, a diluted allergen is injected immediately below the skin surface.
After either type of test, the area of the skin is observed for about 15 minutes to see if a reaction develops. The “wheal”—a raised, red, itchy bump and surrounding “flare”—indicates the presence of the allergy antibody when the person is exposed to specific allergens. The larger the wheal and flare, the greater the sensitivity.