Allergy Testing

If you have an allergy, your body is reacting to something you inhaled, touched or ate. The substances that trigger an allergic reaction are called allergens. Reactions to these allergens range from annoying to life-threatening.  Many people with untreated allergy symptoms aren’t aware of how much better they can feel once their symptoms are properly diagnosed and managed by an allergist / immunologist, often referred to as an allergist.

Types of Allergy Tests

Different allergens bother different people, so your allergist will determine which test is the best for you.  The allergen extracts or vaccines used in allergy tests performed by allergists meet U.S. Food and Drug Administration (FDA) requirements, making them safe for use.

Skin Test

Here at Hill Country Allergy & Asthma we determine your degree of allergy through a procedure called skin testing where the prick test and the intradermal (under the skin) test are used. With each test, you will be exposed to small amounts of things to which you may be allergic. If you are allergic to a substance a reaction will appear which looks like a mosquito bite. The doctor and/or nurse will examine any reaction that appears to decide whether a positive reaction has occurred indicating allergy.

In the prick test, allergens are applied by tiny pokes that penetrate only the very top layer of skin.  These pokes will rarely draw blood. You feel only a slight prick or scraping of the skin. Reactions are usually seen in ten to thirty minutes if they are going to occur, and you generally won’t have any other symptoms besides the small hives where the tests were done, which go away within 30 minutes.

*A skin test has to be done in an allergist’s office to minimize the risk of rare side effects.

The intradermal test involves the injection of a small amount of allergen placed with a needle just under the skin. This pushes the skin up slightly, producing a round whitish, raised area called a wheal.  This procedure is not as painful as the usual injection, because only a small amount of allergen is injected and the small needle slips barely under the skin surface. Any reaction usually occurs within ten to twenty minutes.

The prick method has the advantage of letting the doctor test a large number of allergens at one time. Intradermals are used as a confirmatory test.  The doctor will decide whether to use one or both methods for the testing. A MULTI-TEST is a sterile disposable, multiple test head applicator used to administer skin test substances. It provides a quick, convenient, and standardized procedure and is frequently used for children. There are eight tests on each device.

This type of testing is the most common and is least invasive.  If you are allergic to ragweed pollen but not to cats, only the ragweed allergen will cause a little swelling or itching. The spot where the cat allergen was applied will remain normal.

Challenge Tests

In a challenge test, a very small amount of an allergen is inhaled or taken by mouth. Challenges are done mostly with potential food or medication allergies, and it is very important that they be supervised by an allergist.

Blood Tests

This test involves drawing blood, so results are not available as rapidly as with skin tests. Blood tests are more limited and are generally used when skin tests might be unsafe or won’t work, such as if you are taking certain medications, or have a skin condition that may interfere with skin testing.

When to Proceed with Caution

There are methods of allergy testing that the American Academy of Allergy, Asthma & Immunology (AAAAI) and the American College of Allergy, Asthma and Immunology (ACAAI) believe are not useful or effective. These include: immunoglobulin G (IgG) testing, massive allergy screening tests done in supermarkets or drug stores, applied kinesiology (allergy testing through muscle relaxation), cytotoxicity testing, skin titration (Rinkel method), provocative and neutralization (subcutaneous) testing or sublingual provocation.

What Are the Benefits of Allergy Testing?

Allergy tests, combined with the knowledge of your allergy specialist to interpret them, can give precise information about what you are as well as what you are not allergic to. Allergy testing should always occur along with a physical examination and a discussion about your past and current symptoms.  For instance, if you wheeze when you are at home and don’t know why, you don’t have to get rid of your cat if your allergy testing shows you are allergic to dust mites but not cats. With this information, you and your allergist can develop a treatment plan to manage or even get rid of your symptoms.

Should I be Tested?

Testing done by an allergist is generally safe and effective for adults and children of all ages.

Symptoms which usually prompt the allergist to perform skin testing include:

• Respiratory: itchy eyes, nose or throat; nasal congestion, runny nose, watery eyes, chest congestion, cough or wheezing
• Skin: hives, itchiness or atopic dermatitis
• Abdominal: cramping and diarrhea or constipation consistently after eating certain foods
• Severe reactions to stinging insect stings (other than swelling at the site of the sting)
• Anaphylaxis (an-a-fi-LAK-sis): a serious allergic reaction that affects many parts of the body at the same time

Most symptoms are caused by one or more of these allergens:

• Dust mites (tiny bugs you can’t see) that live in your home
• Proteins from furry pets, which are found in their dander, saliva and urine
• Molds in your home or in the air outside
• Tree, grass and weed pollen
• Cockroach body parts and droppings

More serious allergic reactions can be caused by:

• Venom from the stings of bees, wasps, yellow jackets, fire ants and other stinging insects
• Certain foods
• Natural rubber latex
• Certain medications and drugs

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