Allergy Testing: Why You Should See an Allergist, and What to Expect


Allergy Testing: Why You Should See an Allergist, and What to Expect

It’s normal to trust your child’s pediatrician with various tests, screenings and procedures. But allergy testing is best left to an allergist.

As it turns out, nearly half of all primary care doctors ordered a blood panel test for food allergies when barely 1 percent of all allergists choose to use the same test.

Because the panel test screens for multiple allergies at once, it’s not as precise as other available methods. Pediatricians or primary care doctors use it because it seems convenient: one test to detect multiple allergies. They are simply not well-trained enough in food allergies to know that this system is flawed and that a better alternative exists.

What does that mean for your child?

It means the results of your child’s panel test might be misinterpreted or simply be inaccurate. Your child may be diagnosed with a food allergy that he or she does not really have.

Food allergies are an annoyance at best and life-changing at worst, causing parents to rethink how they feed their child and to worry about potential cross-contamination. Think of all the hassle and stress that might be ahead of you if your pediatrician uses an imprecise test and gives an inaccurate answer.

It’s best to go to an allergist who has plenty of experience in food allergies.

What to Expect During Allergy Testing

An allergist won’t take a blood sample to test for allergies. Instead, a grid is drawn on the skin (usually the forearm or the back) with a pen and each square is labelled with a type of food. Then the corresponding food extract is dropped onto the skin in each square. The skin under the droplet is pricked.

Although the pricks might be a little uncomfortable, the amount of food used in the tests is so small that these tests are quite safe.

You’ll have to wait about 20 minutes for any raised, red bumps to appear on the skin in each square. (Many allergists put on a TV show or a movie to help the time go by, but you might want to bring along a few books or maybe a tablet game.)

If the skin is unchanged, it means your child is not allergic to that food item. If the skin is indeed red and bumpy, an allergic reaction has occurred.

Challenge Tests

If your child tests positive for a peanut allergy and you say, “But we eat PB&Js all the time at home. What gives??” then your allergist might recommend a challenge test. This means gradually increasing the amount of food (in this example, peanuts) to see when a reaction occurs. Only do this with your allergist’s guidance and be clear on what to do if a serious reaction does occur.

Allergists may survey you or your child to further determine whether an allergy to a certain food is likely. He or she may ask:

  • What kind of symptoms occur after eating the food
  • How much of the food is eaten before symptoms occur
  • How long after eating the food do the symptoms occur
  • How many times has the food been eaten and then followed by these symptoms


If a processed food causes a reaction, you may be asked to separate the ingredients out in order to test them individually. For example, cinnamon is a potential food allergen, but when it appears in cookies alongside milk ingredients, it’s impossible to know which allergen is the culprit.

In short, allergy tests vary, but the best person to help you get to the bottom of the mystery is an allergist, not a pediatrician or primary care doctor.

6 thoughts on “Allergy Testing: Why You Should See an Allergist, and What to Expect

  1. My son has had some allergic reactions lately, but we can’t quite pinpoint what is causing it. The article mentions that an allergy test uses a skin prick to determine what you are allergic to. The article mentioned food, but can this be done for things like plant pollen and animals too? I want to make sure we know exactly what is causing the problem.

  2. Hi, John. Thanks for your comment and question. The answer is yes, absolutely. I used to work for an allergist, myself, and both kids and adults were tested for up to 40 allergens at one time with skin prick or “scratch” tests on their back and/or forearm. The environmental allergens tested for included things like pollen, dust mites, pet dander and mold and a myriad of other things that could be causing the problem.

  3. I’m glad you talked about skin turns red during an allergy test if you are allergic to something and how it stays the same if you’re not. My son says his tongue feels swollen after he eats strawberries. Maybe if I take him to an allergist, they can determine with a test if he’s really allergic to them and treat him if he is.

    1. Violette, we do recommend seeing an allergist based on what your son describes. There are a wide variety of ways kids (and adults too) describe what an allergic reaction feels like, and a tongue that feels swollen — even if it might not look that way — is definitely something to take seriously and investigate further. If it is in fact an allergy, a future reaction could be worse, so it would be a good idea to know what you’re dealing with. We all wish you and your son the best.

  4. I’m glad that you talked about how the bumps on the skin will take about 20 minutes to start showing up. I have been looking for a way to find out what my son is allergic to. I can see how it would be nice to only wait 20 minutes because I have been really busy recently.

  5. I had no idea that allergists do not use blood tests when figuring out your child’s allergies. It is important to understand that learning how this process works can help you find the best way to care for your child and know how to help with their allergies. My son has been getting hives and we want to make sure we know what he is allergic to in order to find the best treatment for him, so I’m glad I found your post.

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