Linda Cox, MD, is a board certified allergist and immunologist. She is currently the associate clinical professor in medicine at Nova Southeastern University and operates a private practice in Ft. Lauderdale. Dr. Cox serves as a chair person on the Immunotherapy and Diagnostics Committee of the American College of Asthma, Allergy & Immunology (ACAAI). She also holds a chair position with the IgE Test Task Force for both the ACAAI as well as the American Academy of Allergy Asthma and Immunology (AAAI).
How can a person tell if he or she needs an allergy test?
One can be tested for food or airborne allergens depending on the clinical situation. Persons with year-round nasal or eye allergy symptoms should consider allergy testing to determine what may be triggering their symptoms. Persons with seasonal allergies should consider testing if their symptoms are not controlled with medications or they want to know what they are allergic to.
I also think children with seasonal and year-round allergic rhinitis should be evaluated for allergies because allergic rhinitis is a risk factor for asthma, and some interventions, such as immunotherapy, may prevent development of new allergies and asthma.
For patients with asthma, NIH Expert Panel Guidelines on asthma managements recommends (J Allergy Clin Immunol 2007;120:S94-138.):
“Identify allergen and irritant exposures. The most important allergens for both children and adults appear to be those that are inhaled. For patients who have persistent asthma, use skin testing or in vitro testing to assess sensitivity to perennial indoor allergens. Assess the significance of positive tests in the context of the person’s history of symptoms when exposed to the allergen.”
Also, children with atopic dermatitis (eczema) should be evaluated for allergies - possible food and aeroallergens - again, depending on the history.
Why is allergy testing important?
Allergy tests give very specific information about what you are and are not allergic to. Once specific allergen(s) have been identified, an appropriate treatment plan can be developed that may include avoidance measure, environmental control measure or allergen immunotherapy.
What are the most common types of allergy tests? How do they work?
There are two types. Skin tests (two kinds: percutaneous, also known as prick tests, and intradermal) and blood tests (serum specific IgE).
Prick tests: A very small amount of allergens are put into your skin by making a small indentation or “prick” on the surface of the skin through a drop of the allergen extract.
Intradermal tests: These tests involve injecting a small amount of allergen within the skin.
In both prick and intradermal tests, a wheal surrounded by redness will appear within 15 minutes if you have allergy antibodies to that particular substance.
Allergy blood tests: These test a person’s blood to see if they have allergy antibodies (sIgE) that react against specific allergens.
Which testing method is most effective?
We think of these tests in terms of specificity (high specificity=no false positive reactions) and sensitivity (high sensitivity = no false negative reactions).
Intradermal is the most sensitive but least specific so there are more false positives. Prick testing is similar to allergy blood testing in terms of sensitivity, but the results are obtained much faster (within 15 minutes of pricking the skin with the allergen), whereas allergy blood tests can take a week and require a second office visit to review.
Are there any risks or side effects involved with taking allergy tests?
For skin tests, the most common adverse reaction is an immediate red, itching bump at the injection site. In some cases, a similar delayed reaction can occur six to 24 hours later. Very rarely, systemic reactions include generalized itching, chest tightness/wheezing or dizziness due to a drop in blood pressure.
Are there any preparatory steps one should take prior to having an allergy test conducted?
Avoid antihistamines. The number of days that you need to stop a particular antihistamine will depend on how long the antihistamine stays in your body (its half-life). Contact the allergy office where you will be getting the testing done if you have any questions about medications that may interfere with testing.
What type of education or training is needed to administer an allergy test?
Allergy skin test technicians should be trained on how to perform the allergy skin testing. Some offices have the manufacturer of the allergy testing device train the technician on how to properly use their particular device. Allergy skin test technicians should also go through allergy skin test proficiency testing after completing their training. The proficiency testing confirms that they have adequate and reproducible testing skills.
What is the most significant piece of advice you can offer to people who wish to get tested for allergies?
It is very important that you consult a board certified, eligible allergist for your allergy evaluation because he or she has the advanced training and expertise in the techniques of finding out what is causing an allergic reaction and how best to solve the problem.
Do you have any further comments regarding allergy testing?
It is simple, fast, not painful and provides a lot of useful information about what you are and are not allergic to and will help you manage and control your allergies.
GET TESTED! GET TREATED! GET BETTER!
For more information on allergy tests, read our Allergy Test Guide. To find a test kit or provider, consult Tests.com's Allergy Test Directory.
