Which type of allergy testing involves applying an allergen to the skin?

The correct answer involves a method where allergens are applied directly to the skin to identify sensitivities. In patch testing, small amounts of potential allergens are applied to patches, which are then adhered to the skin, typically on the back. The patches remain in place for 48 hours, during which time any reaction to the allergens is assessed. This method is particularly useful for identifying delayed allergic reactions, such as those caused by substances like poison ivy, metals, or certain chemicals in personal care products.

In contrast, skin prick testing involves making small punctures to the skin and applying allergens directly to those punctures, allowing for immediate reactions to be observed. Intravenous testing typically involves delivering allergens through an IV, and blood testing measures specific IgE antibodies in the blood rather than testing on the skin. Therefore, patch testing is the specific method of skin application used to test for particular allergies.