How do you test for allergies?

There are several different tests that allergists use to diagnose allergies, including:

1. Skin prick test: A small amount of allergen extract is placed on the skin, usually on the arm or back, and a small prick is made through the extract with a needle. This test is used to identify immediate allergic reactions to various allergens.
2. Intradermal test: Similar to the skin prick test, but the allergen extract is injected into the skin using a small needle. This test is used to identify allergies to specific allergens, such as venom from insect stings.
3. Blood test: A blood sample is taken and sent to a laboratory for analysis. These tests are used to measure the level of allergen-specific antibodies in the blood, which can indicate an allergic reaction. These are also called RAST (Radioallergosorbent test)
4. Patch test: A small patch containing an allergen extract is applied to the skin, usually on the back, and worn for 48 hours. This test is used to identify delayed allergic reactions to allergens that come into contact with the skin, such as poison ivy or nickel.
5. Challenge test: An allergist will give a small dose of allergen to the patient under close medical supervision, usually through the nose or mouth. This test is used to confirm a diagnosis of a food allergy or an allergy to a medication.

These tests help allergists to identify the specific allergens that are causing symptoms, and then make recommendations for treatment and management of the allergies.