What are allergy tests?
Your doctor will have many questions about your overall health history and your allergic symptoms. This information will help your doctor determine what type of allergy you have. It is important for your doctor to know what kind of symptoms you have and how severe they are. Since you may not have symptoms on the day you see the doctor, you may want to think about your symptoms and write down as much as you can before your visit. Then, be sure to bring your notes with you to your next visit to the doctor’s office. Since your doctor may ask about your family history of allergies, it is a good idea to talk with other family members about that before your visit to the doctor. You may find that some family members do not have any obvious allergic symptoms, such as sneezing, runny nose or itchy eyes, but may have severe headaches or chronic nasal congestion that may be related to an allergy. Any information you are able to obtain will be helpful to your doctor. Be sure to stop taking any antihistamines like claritin, benadryl, clarinex, allegra or zyrtec that you may be currently on if you are expecting to have an allergy test. Tests done with antihistamines still in your body may turn out false negative and may need to be repeated.
When you first arrive at your doctor’s office, you may be asked to fill out forms about your symptoms. These forms will also ask about any known triggers, as well as any pattern of symptoms.
Your doctor will examine you and focus on the areas of the body that are affected by allergy symptoms. You may also have allergy testing done at this time to identify specific substances you are allergic to. These tests may include skin or blood tests. Skin tests may include a prick test or a patch test. In the prick (scratch) test, a few drops of the purified allergen are gently pricked on to the skin surface, usually the forearm or the back. This test is usually done in order to identify allergies to pet dander, dust, pollen, foods or dust mites.
Intradermal injections are done by injecting a small amount of allergen just beneath the skin surface. The test is done to assess allergies to drugs like penicillin or bee venom.
The patch test simply uses a large patch which has different allergens on it. The patch is applied onto the skin, usually on the back. The allergens on the patch include latex, medications, preservatives, hair dyes, fragrances, resins and various metals. When a patch is applied the subject should avoid bathing or exercise for at least 48 hours. A positive reaction may cause itchiness, swelling although less commonly shortness of breath wheezing or symptoms of anaphylaxis may also occur.
Blood tests usually screen for the antibodies that cause allergic responses – they are not always accurate in telling whether you are or are not allergic to a particular allergen. Dr. Dagan routinely performs a blood test that is called the Northeastern blood allergen test. It tests for all the common varieties of tree pollen, grasses, weeds, molds, house dust and house dustmite, pet dander, goose and duck feathers (contained in down comforters), common insects and the gamut of food groups including various shell fish, fish, meats, milk, soy, fruits, vegetables, nuts.
If there is a specific substance that you are interested in testing for let us know, our lab can usually accommodate nearly every request.
You may also undergo breathing tests or x-rays to see if your allergies may be affecting your lungs or your breathing.