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Knowing the foods that cause your child’s food allergy reactions can help you best manage their allergy, reduce stress, and avoid restricting their diet unnecessarily. To help diagnose a food allergy, an allergist may recommend allergy tests.

But allergy tests only tell part of the story. Instead, food allergy tests work with your child’s personal, medical, and symptom history to help your child’s doctor confirm their allergens.

What Do Food Allergy Tests Look For?

There are two categories of food allergies:

Food allergy tests are best for IgE-mediated food allergies. They are rarely recommended for non-IgE-mediated food allergies.

What Are the Most Commonly Used Food Allergy Tests?

There are four types of food allergy tests that are most often used by allergists:

  • Skin prick test
  • Specific IgE (sIgE) blood test
  • Component test
  • Oral food challenge

Skin Prick Test

Skin prick testing (SPT) is one of the most commonly used allergy tests. You may have heard it called a “scratch test.” With SPT, the allergist places a drop of an allergen on your child’s skin and the lightly pricks it. This causes the allergen to go into the top layer of the skin.

Skin prick test on a person's back

If your child has IgE antibodies – immune cells that react with an allergen and cause an allergic reaction – to the food, they will develop a red, itchy bump. This bump is called a wheal or a flare.

Just because your child reacts to the allergen doesn’t mean they are allergic to the allergen. But if your child has had symptoms in the past when eating the allergen, SPT can help confirm the allergy.

Specific IgE Blood Test

The specific IgE (sIgE) blood test measures levels of specific IgE in the blood for certain foods. This test was previously known as RAST or ImmunoCAP testing. The allergen will be introduced into a sample of your child’s blood to see if IgE antibodies are found.

Like SPT, a positive result doesn’t mean your child is allergic. It can be used to confirm a diagnosis if other factors suggest an allergy. Also, the results – or “class levels” – don’t relate to whether or not your child is more likely to have anaphylaxis. Your child can have a low class level and still have a severe allergic reaction.

Component Test

A component test is another type of blood test. It’s different from other tests because it looks at IgE levels in the blood to different proteins in a food instead of the whole food. These tests are designed to try and determine if your child’s IgE tests are elevated due to true food allergy or are false positives from cross-reactivity with inhalant allergens.

Oral Food Challenge (OFC)

The best way to know if your child is actually allergic to a food is to have them eat it during an oral food challenge (OFC) in an allergist’s office. It’s the gold standard for confirming whether or not your child has a food allergy.

A doctor observes a mother feeding her child during an oral food challenge to test for a food allergy

In an OFC, your child eats small, increasing amounts of their suspected food allergen. The allergist and their staff watch your child for a reaction and are prepared to treat any symptoms, if they arise. It’s the most reliable allergy test for food allergies.

What Should I Do If I Think My Child Has a Food Allergy?

If you think your child has a food allergy, see a board-certified allergist, if possible. They know how to look at your child’s full history along with allergy tests to confirm or rule out a food allergy. Avoiding foods without a proper diagnosis can lead to issues like food anxiety, poor quality of life, and poor nutrition – factors that can have a major impact on your child’s well-being, health, and development.

Medical review: June 2023 by David Stukus, MD

It is important to stay up to date on news about food allergies. By joining our community and following our blog, you will receive news about research and treatments. Our community also provides an opportunity to connect with other people who manage food allergies for support.

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  • Dr. David Stukus: KFA Medical Advisory Team Member
  • A doctor observes a mother feeding her child during an oral food challenge to test for a food allergy: A doctor observes a mother feeding her child during an oral food challenge to test for a food allergy
  • Skin prick test on a person's back: Skin prick test on a person's back

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Comments (46)

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I am wondering if there’s any information about how  a combination of foods may contribute to an allergic reaction. At times I have had a mild reaction after ingesting a small amount of food with peanuts. Other times I have had a more severe reaction. So could it be that there is some other protein or substance that intensifies the reaction?  I have read some of the questions that parents have posted about inconsistent results and it made me reflect on my own experiences as an adult with a peanut allergy since infancy.  I know that this is a site for parents but I have greatly benefitted from information and have shared info with others.  

E
camnicemm posted:

Any thoughts or direction on behavioral issues due to food? My now 6 year old daughter never had any stomach issues, eczema, or anything else, but she became absolutely uncontrollable (threatening to kill me, punching, kicking)after a strep infection back in February. I figured something had to have happened and had the doctor do all the gluten related bloodwork since it was just not her and her oldest brother is GFCF. Sure enough, it came back positive. The allergist put her on an elimination diet and we found she reacts just as strongly to corn - again only with behavior. Didn't show up with his tests so he thinks I'm a lunatic but about 36 hours after eating something with corn, her behavior starts going downhill and it takes over a week to get it all back out of her system. How do I find a doctor who will take me seriously and not just blow me off because he doesn't see a physical reaction?

 

I realize your post is from 2012 but in reading the comments trying to find a solution for my daughter's situation, I had to write in the event you were still having issues.
Please google PANDAS in regards to your daughter's violent behavior after having Strep throat. There is a direct link. It has been in the news a lot recently.
 
 
Lara707

Hi There,

I would really appreciate your guidance. My boy who is now over 3 years has had 3 reactions to eating hake. The 1st one happened when he was 6 months old and the 2 times after happened when he was just over 1 year. His symptoms occur about 2 hours after ingestion, vomiting severely for a few hours, lethargic and non-responsive until it is all out his system. The last episode he did have runny tummy the day after.

On all 3 occasions we took him to emergency to be monitored. They gave him Zofar for vomiting under his tongue and liquid to re-hydrate.  After visiting an allergy clinic and specialist, a skin prick test was done, showing he was allergic to all fish and sea food. We were advised to have him retested at 3 years old. 

My boy turned 3 in July. We have just visited the allergy clinic again to have him retested. He had a skin prick test which came up negative and a blood test which has also come back negative.

The specialist is now suggesting we admit him into hospital to have an introduction to fish under supervision.

My questions is - is this necessary? to have to put him through another day in hospital, the trauma of having another needle in him plus the additional cost of such a procedure.

Surely if both tests have come back negative, could we not start introducing small amounts of fish at home? Or even sit in the hospital cafe and let him taste fish should a reaction occur?

Please help!!!

Many thanks

Lianne

Lianne Godfrey

Hi, and welcome, @AGlick0927! Hugs on the reactions and the conflicting test results on peanuts. You're definitely in the right place to get support!

Your questions are great, and it sounds like you still have some things you might want to discuss with your allergist. 

Another thing you might want to discuss with your allergist is component testing for both milk and peanuts, if you haven't already done so. Component testing can tell a doctor what particular protein in milk or peanuts a person is sensitive to, and that can help the doctor decide whether an oral challenge is appropriate. 

Since you guys are planning on doing an oral challenge, KFA has a great resource on oral food challenges

Why not post this question to our Main Support Forum so you can get more feedback from other folks in a similar situation? If you're on desktop view, just follow the link above, and click on the big green POST. On mobile, click the three horizontal lines in the upper left hand corner, and you'll see POST. Click that, and you'll be able to add your comment as a new post.  

K8sMom2002

Hello! My 2.5 year old daughter has tested positive to peanuts, tree nuts, egg and dairy on a skin test (2 different times) She has had reactions to both egg and dairy, however she has never ingested any nuts.

We just received the results of her first ever blood test and it confirmed egg and dairy, however it came back negative to all nuts! We will be scheduling an in office peanut challenge.

My question is, since I know that false negatives are more rare than false positives, should I feel optimistic that we actually have a chance at not being allergic to peanuts or tree nuts?

Additionally, our allergist is suggesting we do a BAKED milk challenge based on numbers, however this scares me because I've seen her reaction to dairy in the past and I hate to think of having to go through that again.

Thank you so much!

A

Hi, Lune! Since you're having symptoms when you eat food, I agree with Jen -- a board certified food allergist is definitely someone to consult. You may also want to touch base with a dermatologist as well.

Why not post this question to our Main Support Forum so you can get more feedback from other folks in a similar situation? If you're on desktop view, just follow the link above, and click on the big green POST. On mobile, click the three horizontal lines in the upper left hand corner, and you'll see POST. Click that, and you'll be able to add your comment as a new post.  

Your comment caught my eye because my DD has an allergy to apple that is in line with something called OAS (oral allergy syndrome). You can find out more about it under KFA's resource on the types of food allergies.

Also, my DD had/has eczema (worse when she was little, better now as a teen), and I have flare ups of eczema on my eyelids.

Not all eczema is related to foods, and even if a food is a trigger for eczema, some allergists and dermatologists recommend other techniques besides avoiding that food. You can find some of those techniques here on KFA's resources for eczema

K8sMom2002

So as far as I remember I suffered with bad eczema rashes since I was little and my parents somehow managed to keep it at bay. No nuts, dairy and limited amount of citrus acidic and sugar food, I have had no issues with eczema for more than ten years and thought it went away--- I was wrong. I recently started having bad eczema flare upd around my face. Eyelids, under eyes, chins and around mouth. It's swelling, itchy and bumpy and I have no idea what is causing it. I have been eating nuts, dairies and acidic food without no problems but something (could it be environmetal?) is triggering it pretty bad. I am very curious about testing for food allergy but please let me know if you have any recommendations for different types of testing.

Also, I have been loving seafood all my life even as a kid but I found out recently that after consuming salmon or tuna my face feels little itchy. Same goes for apple and cherries. I love eating them but my mouth gets so itchy after and my lips swells. Could I have developed some kind of food allergy? And how do I manage it if I can't give up on eating them? 

L
Mehmet posted:

Can somebody be okay eating a food but not be okay touching it? 

My daughter (5 years old) successfully passed two oral food challenges for hazelnuts, which included eating increasing amounts of hazelnuts and also a spoon full of Nutella (this was given after she had eaten her last dose of hazelnuts). There were no symptoms or problems at all. So I (and our allergist) think it's safe to assume that she is no longer allergic to hazelnuts and we are obviously very grateful for that. 

However, whenever we give her Nutella at home and something gets stuck around her mouth or on her lips, her skin reacts. The skin turns red (not itchy though) and her lips "hurt" a little bit (that's her description, it may be itchy). This disappears quickly after we wash it off with water.

We've check all the other ingredients in Nutella but everything seems to be fine. Any idea of what could cause these reactions. Our allergist suggests that she may just have sensitive skin. I hope that's the case but why the bumps on her lips then?     

Welcome Mehmet!

May I ask when you did two food challenges?  Just curious...

Does she have any other allergies?

The redness and the lips "hurting" would have me think that she could possibly still be allergic to it.  How much is she eating at home?

As Cynthia mentioned, be sure to visit us in our Main Support Forum where others can chime in as well with their experiences.

Katie D

That's an interesting question, Mehmet ... and one that I can't answer. But I suspect if you post this question onto our main support forum (click here for our Main Support Forum. ), you may get other people who have had experience with this.

Also, someone wiser than me may be able to move your question over there for you.

K8sMom2002

Can somebody be okay eating a food but not be okay touching it? 

My daughter (5 years old) successfully passed two oral food challenges for hazelnuts, which included eating increasing amounts of hazelnuts and also a spoon full of Nutella (this was given after she had eaten her last dose of hazelnuts). There were no symptoms or problems at all. So I (and our allergist) think it's safe to assume that she is no longer allergic to hazelnuts and we are obviously very grateful for that. 

However, whenever we give her Nutella at home and something gets stuck around her mouth or on her lips, her skin reacts. The skin turns red (not itchy though) and her lips "hurt" a little bit (that's her description, it may be itchy). This disappears quickly after we wash it off with water.

We've check all the other ingredients in Nutella but everything seems to be fine. Any idea of what could cause these reactions. Our allergist suggests that she may just have sensitive skin. I hope that's the case but why the bumps on her lips then?     

M

We often mess up between food allergy and food intolerance. Food allergy usually comes on suddenly. Even a small amount of food can trigger an allergic reaction. Food allergy appens every time you eat that particular foo and can be life-threatening too. On the other hand, food intolerance generally comes on graduall and occurs when you eat a lot of that particular food. It is not life-threatening

T

Dr. Stukus -

Thank you for sharing this information.  I agree with much of what you had to say and wanted to know if you would ever recommend the "Gold Standard" for accommodations in school?  I have two children with close to 40 ER visits between them for allergic reactions.  One has had RAST scores over 100 to Peanuts since infancy - he is 12.  The other has RAST over 100 to Dairy and Eggs since infancy - she is 8.  They both had systemic reactions to skin testing done last summer.  They were denied accommodations in school under their 504 plan so, we went through Due Process litigation to get those accommodations.  The Dr who testified for the school district is a very well known pediatrician / advocate in the food allergy community.  She has never met my children, never performed skin testing or treated patients for food allergies.  She testified that she was not so sure that our children even had food allergies since our Allergist (with 40+ years of experience - including work at National Jewish) had failed to perform the oral food challenges on our kids.  Our Allergist testified that our children are contact, airborne and ingest to their allergens based on their history, skin and RAST tests.  Because of the pediatrician's testimony and her experience in the food allergy community, the judge ruled with her recommendation of oral and inhalation food challenges for both of our children.  The judge stated that because we failed to provide the burden of proof by submitting our children to both oral and inhalation challenges that the school district would not have to accommodate our children.  Would you ever advise a patient to undergo an oral food challenge under such a circumstance?  What are your thoughts?  Thanks!  

L
Last edited by lovebugsco

Missy24, sorry to hear that your son had a severe reaction to cashew. Unfortunately you can develop allergies at any time, so in his case he was not allergic before but then became allergic.  The article is referring to testing positive to a food but being able to eat it without reaction.  Some docs will run a panel to whole list of foods, even if the patient has only reacted to one.  This can lead to avoiding more foods than is necessary as there is a high chance of false positives with allergy testing.

A
My son ate cashews by the handful with absolutely no reaction and then went into anaphylactic shock after eating one.  How does that fit into this?  This stated that if you can eat something without reaction you aren't allergic.  He reacted to walnuts which now that we've had testing are still high but lower than both peanuts and cashews.
M

Regarding the MRT and it's usefulness for the treatment of food sensitivities, not food allergies... The absence of a particular type of reference on PubMed does not denote the absence of clinical utility in the treatment of the targeted disease states, especially for newer emerging complementary treatments.The establishment of clinical utility of new complementary treatments usually precedes the appearance of references on Pubmed, often by many years.

Dr. Stukus, I will be happy to send you information on MRT as well as contact info for physicians who use MRT in their practices.

I find it difficult advocate a blind elimination diet for type 3 & 4 food hypersensitivity (non-IgE-mediated reactions),when a test to detect type 3 & 4 food hypersensitivity,w/proven 93% accuracy,is available. Not only does the blind elimination often prove unsuccessful in detecting triggers of symptoms, but poses the risk of malnutrition,particularly in children.

 

 

 

L

Yes, we've been seeing allergists since she was 6 or 9 months old.  We have moved a couple of times and had to switch allergists and it can be confusing, some say lip swelling alone is anaphylaxis, what she had with banana and mustard, and some say it's not.  It's hard when allergist's don't agree. 

DeirdreRiley

Maggie - I would say discussion about egg free flu shots is outside the scope of this particular blog post - but I can tell you we will be doing a blog post in the near future about egg allergy and flu vaccine, so that should provide some more insight on this issue. Stay tuned!

 

Deidre - negative test results are usually accurate, but in a small percentage of cases, children can react with negative test results.  That is why it's important to get evaluated by an allergist, since they are most qualified to sort these types of situations out (and not rely on test results alone). Glad to see you are working with an allergist!

 

Gale - Thanks for the suggestion.

Lynda

My daughter (now 16 years old) was diagnosed at age 2 and had two subsequent positive skin tests to peanuts and tree nuts, but has never had a reaction at all other than her first (to walnut) at about 1 yr old. So I was hoping that the peanut positive was a false positive all along. We had component testing done recently, using the Uknow peanut test through Phadia (Thermo Fisher Scientific) which we were told was more comprehensive and accurate and the results show a severe peanut allergy. I'd like to learn more about component testing (in layman's terms).

G

The predictive values for likelihood of an allergy being present differ with every food, but in general, the higher the level, the more likely that an IgE mediated allergy is present.

My daughter actually tested negative several times to some things as a baby despite reacting to them and then went on to test positive with low numbers.

 

With egg for example her IgE was about 1.2, but she failed the in office food challenge with the initial dose of egg powder before the real food.

 

She also tests positve with 1.92 and 1.98 to mustard and banana but just a tiny pin prick amount of her first taste of mustard her lip swelled up like a duck, and with 1/4 of a banana the same.

 

Her dairy allergy is over 100 and is her worst, but with these others at 1.9 she still has big reactions.

 

Also as a baby she tested negative to egg and banana but had reactions to them, it wasn't until a couple years later that the test even came up positive, after we retrialed to be sure and she indeed reacted to them again.

 

So the:

 

"negative" results are more likely correct.

 

Didn't fully work with us either.

 

DeirdreRiley