A small amount of the suspected allergy substance is placed on the skin.
The skin is then gently scratched through the small drop with a special sterile needle. This is known as the prick-puncture method and is typically used for initial evaluations. A second method, known as the intradermal method, involves injection of a small amount of the test subtance into the skin. Intradermal testing is more sensitive but also tends to lead to more false-positive results.
If the skin reddens and, more importantly, swells, then an individual is said to be “sensitized” to the particular allergen. If typical symptoms occur when a sensitized individual is exposed to the suspected substance, then allergy to that substance is probable.
The skin testing described is tolerated by the youngest of patients and should be the standard of testing.
Skin testing is not indicated for people who are at risk of a severe (anaphylactic) allergic reaction, who have certain skin conditions, or who are taking certain medications.
