Allery skin tests – what to expect

 Over 50 million people in the United States have allergies.  In order to effectively treat allergies, it is important to find out exactly what you are allergic to.  An effective method of discovering what a person may be allergic to is to have skin testing for allergies.  Skin tests for allergies have been around since the 1860s and are still used today as a diagnostic tool. When skin allergy testing is combined with a physical examination and complete medical history, this can give accurate information on what specifically is triggering a person’s allergic reactions.

What is an allergy?

An allergy occurs when a person reacts to things like pollen or pet dander that don’t affect most other people.  People with allergies have hypersensitive immune responses to substances that either enter or come in contact with the body causing an allergic reaction.  They may have symptoms such as itching or sneezing which is called an allergic reaction.  Allergens can be found in food, drinks or the environment.

How is allergy testing done?

Skin allergy testing is one method that can be done on any age, from children to adults.  They are performed in an allergist’s office and will be done under the guidance of an allergy specialist who is trained in the best methods for testing and treating allergies.

The tests for skin allergy testing uses extracts (a form of concentrated liquid form), of common allergies such as pollen, mold, dust mites, animal dander, and foods.  Anywhere from 10 to 50 different allergens are tested at a time. 

There are three main ways an allergy specialist will test skin depending on what type of test a person is having:

·      Scratch test – This test is also known as a puncture or prick test. A drop of a potential allergen is placed on a marked and labeled area of skin usually on the back or forearm.  Then the outer layer of skin will be scratched to let the allergen in. 

·      Intradermal test – This is when a doctor or nurse will inject a small amount of allergen just under the skin.

·      Patch test – The allergen is placed on a patch which is then stuck onto a person’s arm or back. 

In both the scratch and intradermal tests, the actual testing itself takes about 5 to 10 minutes.  A person will be observed for about 15 minutes to see how their skin reacts.  The patch test takes longer since a person will wear the patch for about 48 hours and will have to come back for another visit with the doctor.

When are the results known?

Finding out the results from skin testing is fast as positive reactions usually appear within 20 minutes.  A positive test result is generally easy to know by observing the skin’s reaction – a “wheal” which is a raised, red, itchy bump and surrounding “flare” indicates the presence of the allergy antibody when the person is exposed to specific allergens.  The larger the wheal and flare the greater the sensitivity.     

Is skin allergy testing safe?

Testing for allergies using skin testing is usually safe.  Other than the skin becoming mildly irritated to whatever allergen a person is allergic to, the actual test itself does not hurt.  Even though a person will be in contact with things they may be allergic to, the amounts used in testing is very small. 

It is not uncommon for young children to not like the test because of their skin having to be pricked or scratched.  In addition, skin testing can sometimes be hard to read in people with dark skin. 

It is rare to have a whole body reaction during allergy skin testing but if a person experiences a fever, lightheadedness, trouble breathing, a widespread rash, swelling on their face, lips, or mouth, or has trouble swallowing, they need to let their doctor know right away.

What happens if the skin test shows positive results for allergies?

If a person is found to be sensitive or to have an allergic reaction to certain substances, then an allergist will create a plan for helping to control the allergy by treating and preventing symptoms.  These steps could include:

·      Avoiding or limiting contact with the allergen.  For example, if a person is allergic to dust mites, they would be advised to reduce clutter in their home which can collect dust.

·      They are usually given medicine to relieve symptoms such as a prescription for an antihistamine, decongestant, nasal sprays, or eye drops.

·      A person may be advised to get allergy shots depending on the frequency and severity of symptoms.  Allergy shots contain tiny but increasing amounts of the allergen a person is sensitive to.  Over time, the body will become used to the allergen and should no longer react to it or at least greatly minimize symptoms.