Allergy Testing

You are sneezing, wheezing and coughing. Your eyes are itchy and your nose is running. When you visit your doctor, she says you may have allergies. But to find out exactly what is making you sneeze, you will need to have an allergy testing done.

What is Allergy Testing

If you are allergic, you are reacting to a particular substance. Any substance that can trigger an allergic reaction is called an allergen. To determine which specific substances are triggering your allergies, your allergist will safely and effectively diagnose your skin or sometimes your blood, using tiny amounts of commonly troublesome allergens. Allergy tests are designed to gather the most specific information possible so your doctor, an allergist, can determine what you are allergic to and provide the best treatment.

Which allergens will I be tested for?

Because your physician has made a diagnosis of allergies, you know that one or more allergens is causing your allergic reactions such as itching, swelling, sneezing, wheezing and other symptoms. Your symptoms are probably caused by one of these common allergens:

  1. Products from dust mites (tiny bugs you cannot see) that live in your home
  2. Proteins from furry pets, which are found in their skin secretions (dander), saliva and urine (it’s actually not their hair)
  3. Molds in your home or in the air outside
  4. Tree, grass and weed pollen; and/or cockroach droppings

More serious allergic reactions can be caused by:

  1. Venom from the stings of bees, wasps, yellow jackets, fire ants and other stinging insects
  2. Various foods
  3. Natural rubber latex such as gloves or balloons; or
  4. Drugs such as penicillin

All of these allergens are typically made up of proteins. Various types of allergy testing procedures find which of these proteins you may be reacting to.

The allergen extracts or vaccines used in allergy tests are made commercially and are standardized according to U.S. Food and Drug Administration (FDA) requirements. Your allergist is able to safely test you for allergies to substances listed above using these allergen extracts.

What are specific types of allergy tests?

Scratch or Puncture Test- These tests are done on the surface of the skin. A tiny amount of allergen is scratched across or lightly pricked into the skin. If you have an allergy, the specific allergens that you are allergic to will cause a chain reaction to begin in your body.

People with allergies have an allergic antibody called IgE (immunoglobulin E) in their body. This chemical, which is only found in people with allergies, activates special cells called mast cells. These mast cells release chemicals called mediators, such as histamine, the chemical that causes redness and swelling. With testing, this swelling occurs only in the spots where the tiny amount of allergen to which you are allergic has been scratched onto your skin. So, if you are allergic to ragweed pollen but not to cats, the spot where the ragweed allergen scratched your skin will swell and itch a bit, forming a small dime-sized hive. The spot where the cat allergen scratched your skin will remain normal. This reaction happens quickly within your body.

Test results are available within 15 minutes of testing, so you do not have to wait long to find out what is triggering your allergies, and you will not have any other symptoms besides the slightly swollen, small hives where the test was done; this goes away within 30 minutes.

Intradermal Test- This test is related to the scratch or puncture test, but is slightly more sensitive. It involves injecting a tiny amount of allergen under the skin, usually on the upper arms. Your allergist may do this test when your reaction to the scratch test cannot be clearly determined.

Blood (RAST) Test- Sometimes, your allergist will do a blood test, called a RAST (Radioallergosorbent Test). Since this involves drawing the blood, such allergy test costs more and the results are not available as rapidly as skin tests. RAST tests are generally used only in cases in which skin tests can not be performed, such as on patients taking certain medications or those with skin conditions that may interfere with skin testing.

Challenge Tests- These tests are done only if specific allergy testing is not available and the patient needs the food or medication to which they may be allergic. The test involves having the patient inhale or swallow a very small amount of the suspected allergen, such as milk or an antibiotic. If there is no reaction, the dose may be slowly increased. Since the challenge tests may induce severe allergic reactions, they are only done when absolutely necessary and must be closely supervised by an allergist.

The American Academy of Allergy, Asthma and Immunology, along with many other medical associations, considers some allergy testing methods to be unacceptable in medical practice. According to an AAAAI position statement, these unacceptable tests include cytotoxicity testing, urine autoinjection, skin titration (Rinkel Method), provocative and neutralization (subcutaneous) testing or sublingual provocation. If your physician plans to conduct any of these tests on you, please see an AAAAI member allergist for proper allergy testing. Ensure the safest allergy testing in children too, depending upon various pediatric allergy testings accessible.

Who can be tested for allergies?

Adults and children of any age can be tested for allergies. Because different allergens bother different people. Your allergist will take your medical history to determine which test is the best for you. Some medications can interfere with skin testing. Antihistamines, in particular, can inhibit some of the skin test reactions. Use of antihistamines should be stopped one to several days prior to skin testing.

Reasons for Allergy Testing

To help you manage your allergy symptoms most effectively, your allergist must first determine what is causing your allergy. For instance, you do not have to get rid of your cat if you are allergic to dust mites but not cats; and you do not need to take medication all the year if you have a seasonal allergy to ragweed.

Allergy tests provide concrete information, and once you know the specific allergens causing your symptoms, you can try to:

  1. Avoid exposure to the allergens
  2. Get specific medical treatment, and
  3. If necessary consider specific vaccination with the allergen or “allergy shots”