You may be constantly suffering from the symptoms and signs of allergies, but not really know the culprit. The answer can often be found through allergy testing.
Allergy testing may be needed to find out whether the symptoms are an actual allergy or are caused by other problems. For example, eating contaminated food may cause symptoms similar to food allergies. Some medications can produce non-allergic reactions, including rashes. A runny nose or cough may actually be due to an infection.
In some cases, the doctor may tell you to avoid certain items to see if you get better, or to use suspected items to see if you feel worse. This is often used to check for food or medication allergies.
Skin testing is the most common method of allergy testing. Being "sensitive" means that the immune system produces a type of antibody called IgE against that allergen.
One type of skin testing is the skin prick test, which allows physicians to detect if a person is sensitive to a specific allergen. It involves placing a small amount of the suspected allergy-causing substances on the skin, and then slightly pricking the area so the substance moves under the skin. The skin is closely watched for signs of a reaction, which include swelling and redness. Other types of skin tests include patch testing and intradermal testing. Skin testing may be an option for some young children and infants.
Instead of performing a skin test, doctors may take a blood sample to measure levels of allergen-specific IgE antibodies. Most people who are sensitive to a particular allergen will have IgE antibodies detectable by both skin and blood tests.
Blood tests that may be done include
- Immunoglobulin E (IgE), which measures levels of allergy-related substances
- Complete blood count (CBC) called the eosinophil white blood cell count