Millions of people in United States are affected by different types of allergies. Knowing what causes or triggers an allergic response is important in extending an appropriate and effective treatment for the allergy. With the development of technologies, a number of new medical tests have been introduced to identify the allergen. Reports of allergy tests are then evaluated by symptoms and detailed medical history to identify the allergy causing substances.
Skin tests and blood tests are the two commonly performed tests to find the allergens that trigger a response. Skin tests are more common, as they are less expensive and provide faster results. In skin tests, a small amount of allergens are placed on the skin to test for a reaction.
There are different types of skin tests:
- Skin prick test – In this test, a small drop of the allergen is placed on the skin. The solution containing allergen enters into the skin through small scratches or pricks made on the skin. The development of raised, itchy, red skin at the testing area indicates an allergic response.
- Intradermal test – This test is more sensitive than the skin prick test, and is usually done if the skin test results are negative, but the chemical is considered to be an allergen. In this test, a small amount of the solution containing the allergen is injected into the skin.
- Skin patch test – In this test a small amount of the allergen is placed on a pad attached to the skin. The skin patch test is usually used to detect allergic dermatitis.
Skin prick tests are usually used to test for the presence of mold, dust, feathers, pet dander, and food allergens. It also helps in identifying whether a person is allergic to medicines.
Although it is not as sensitive as skin tests, a blood test is conducted for people who are unable to have skin tests for allergies. One of the most common types of blood tests conducted for allergy is the enzyme-linked immunosorbent assay or ELISA. This test is used to measure the amount of immunoglobulin E in blood. These antibodies are produced in excess in people with allergy. Blood tests are conducted in case of skin conditions, like eczema, hives, and severe allergic reactions.