Last updated: March 2022
Nothing goes together quite like asthma and allergies. It’s like peanut butter and jelly, but terrible and unenjoyable. If you are reading this and have asthma, it is likely that you also have allergies. In fact, it's about a 60% chance, according to the AAFA (Asthma and Allergy Foundation of America).1 Not all asthma is allergic asthma, but it is the majority. For those that are part of this group, you know how important it is to know what you are allergic to.
It can be lots of uncomfortable work to learn what you are allergic to. If you’re like me, it could mean several trips to the ER. While you listen to the people around you trying to guess what caused this anaphylaxis episode, you wonder, 'Is there a better way?’ Yes, there is, and it’s called allergy testing: the less-uncomfortable way to find out what you’re allergic to!
What is an allergy test?
An allergy test is an exam or series of exams that are designed to understand what allergens cause an immune response in your body. They are usually administered after it is clear that a person has allergies or requested by the patient. As noted before, they are not the most comfortable tests to go through.
Types of allergy tests
There are multiple types of allergy tests, each serving a different purpose:
Skin prick test
Skin prick tests are the most common and inexpensive allergy test, and also very accurate in confirming allergens. The test is performed by a physician placing a drop of an allergen on the skin, then pricking or scratching the skin. After about 15 minutes, the skin will show signs of an allergic reaction to confirm an allergy or show no signs to signal a negative.
Intradermal skin test
An intradermal skin test is often used to test for drug or venom allergies. Sometimes if a negative result on a skin prick test is doubted by the doctor an patient, this test is a second test to challenge the negative result. It is conducted by injecting a small amount of an allergen under the top layers of skin, then waiting to see if there is an observable reaction.
This is most common for testing infants, who may not be able to tolerate a skin test. In such a case, a blood sample is taken, then sent to a lab and introduced to various allergens. The lab technicians measure the number of antibodies to determine an allergy. This is much less common than the skin tests because it is infamous for false-positive results.
Physician-supervised challenge test
Most commonly used to confirm food or medication allergies, in a controlled setting. It's done by ingesting an allergen, though the mouth, and waiting for a reaction. It's always done under the direct supervision of an allergist or physician due to the risk of anaphylaxis.
A test designed to better understand a contact-dermatitis allergy. A drop of allergen is placed on the skin, then covered with a bandaid. After 48 to 96 hours the doctor will check the area for a localized rash or reaction to signal an allergy.1
When I was younger, around the age of 10, I was given an allergy test. At the time I was allergic to seemingly everything and my asthma was constantly flared as a consequence. I was administered a skin prick test.
The test started with the doctor making a grid of numbers on my back, I believe there was around 40. Which is an average number.2 Then he used this tool that looked like a small fork to poke my back with a different allergen for each number. The process took some time and after he was finished he left and I waited with my mom for about 15-20 minutes.
During that time, my back started to itch and burn, signaling that I was clearly allergic to at least something he tested. Sure enough, when he returned, I was allergic to most of the allergens he tested for. Small red bumps, like a hive the size of a dime raised on scattered numbers. I learned a lot about my seasonal allergies and the molds or pollens that were causing them. I was also considered a good candidate for allergy shots, which I ultimately decided not to take.
Things to keep in mind
There are some important things to know about allergy shots. Testing positive to an allergen on a skin test does not, by itself, diagnose an allergy and does demonstrate the severity of the allergy. Testing negative on a skin test, usually means you are not allergic to that allergen.1 While the test showed that I was allergic to cats, dogs, and horses, it did not trigger the severe response that I had experienced prior to the test. Also, I tested negative to cinnamon, and I love cinnamon!
Allergy tests are uncomfortable, but they can tell us a lot about our allergies; not everything though. There is no test that will tell you the severity of your allergy, but knowing what you are allergic to is just as helpful. If you are curious about different types of allergy testing and have more questions on how to proceed, contact your primary care physician or an allergist. If your allergies are affecting your asthma, the more you know the better you can protect yourself.
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