If you think that you have allergies, finding out what you are allergic to is the first step to finding an effective treatment. Allergy testing can help identify specific items that trigger your allergies. Skin and blood tests are the two ways you can be tested for allergies. Skin testing includes a combination of skin prick and intradermal testing.
A skin prick test is usually performed on the back by placing a small amount of antigen under the first layer of skin, creating a “wheal”. The wheal is timed for 20 minutes and then measured. The area usually becomes raised, red and itchy if you are sensitive to the allergen.
In an intradermal test, a small amount of the allergen solution is injected under the skin. This test is used when a person does not have a reaction to the skin prick test, but is still believed to be allergic to the allergen. This test is typically performed on the shoulder and can indicate the severity of the allergy.
Blood tests are often used for people who cannot have skin tests. The blood test identifies antibodies in the blood by measuring the blood level of the antibody, which are made by the immune system in response to certain allergies.