Different Types of Allergy Testing

Allergy Testing Allows You to Find Out What Is Causing Your Symptoms

Allergy testing is a way of finding out if you have an allergy to a certain substance. Allergies can make you sick and cause a variety of problems, so it is important to know if you have a food allergy that is causing allergic symptoms. Allergists use two main types of allergy tests to determine if you are allergic to a certain type of food. These are skin tests and blood tests. Skin tests are the most common type of allergy testing used today.

There are three kinds of skin tests

According to the American College of Allergy, Asthma & Immunology (ACAAI), skin testing for a food allergy involves placing a tiny drop of liquid food extract on the skin. The skin is then lightly pricked so that the food substance can penetrate the skin. The patient then waits for about 20 minutes to see if a hive or a red bump develops in the spot where the food extract was placed. The hive may look similar to a mosquito bite. If there is a positive reaction, then the patient is usually told to avoid the particular food that caused the positive result.

Blood tests are used to test for some allergies

Allergists often use blood tests if they suspect that a patient has a peanut allergy or another kind of food allergy that can cause a serious allergic reaction like anaphylaxis. In a blood test, a small amount of blood is examined to find antibodies called immunoglobulin E or IgE. People with allergies often have these antibodies in their blood when they have a food allergy. Blood tests require a waiting period, unlike skin prick tests, but they are sometimes necessary. When a patient has experienced anaphylaxis or has hives, or cannot stop taking an antihistamine or another medication, a blood test is often the best choice. Blood tests are also used if a person has had positive results from a skin test showing that they are allergic to many foods. An enzyme-linked immunosorbent assay (ELISA) can show which food the person is most allergic to.

Allergy testing can rule out food allergy

A person who has had an allergic reaction after eating a certain food may find out on their own what they are allergic to. If they eat peanut butter
crackers and a rash develops soon afterward, they may assume that they are allergic to peanuts. In reality, their allergy could be to wheat, or to
another substance that they ate. Allergy testing has several advantages, such as the fact that it helps you know exactly which food allergy you may have. It also helps the patient know if it is safe to eat certain foods that they may otherwise avoid.

If the allergy test is negative and the patient continues to have the same symptoms that appear to be an allergic reaction, the allergist may do a challenge test. This involves drinking a small amount of liquid with the suspected allergen in it. This test is usually performed in the doctor's office in case a serious allergic reaction
occurs.