A Quick Guide to Allergen Component Testing

July 21, 2021 | Luke Lemons | Medically reviewed by Rebecca Rosenberger, MMSc, PA-C

Allergies can be confusing. For some, enjoying a fresh peanut butter cookie might cause just a little itchiness in the mouth, but for others even a nibble could send them into anaphylactic shock.

This discrepancy in allergic reactions to the same allergens raises a flurry of questions. Why is it that different people react to the same food allergens differently? Or, why is it that only some dogs cause sneezing and itchy eyes, but others don’t?

It turns out that allergies aren’t as simple as we once thought, but luckily advances in allergy diagnostics can now help us better understand how and why allergies operate the way they do. The following Q&As help uncover the different components involved in allergies. 

All living things are made up of millions of different types of proteins. Whether you're talking about bananas or chihuahuas, all organic life is built piece by piece by proteins.

So when we look at allergies such as pet dander allergy or tree nut allergy, we have to ask: “What proteins are people actually reacting to?”

It turns out that for some allergies, there are multiple types of proteins a person may be responding to.

For example, let’s look at a few of the different proteins found in milk and eggs: 


  • casein
  • α-lactalbumin
  • β-lactoglobulin


  • ovalbumin
  • ovomucoid

Not all proteins are made equally and being allergic to a specific protein could mean you might have a more severe reaction when exposed. In milk and egg, being allergic to only α-lactalbumin, β-lactoglobulin, or ovalbumin may indicate that you’ll be able to tolerate baked forms of milk and eggs but not raw forms.1-4

The same differentiation in protein severity can be applied to dog allergy as well. It may be you're not allergic to all dogs but only a protein found in male dogs.5

Discovering which proteins are contributing to your allergies is an important step in not only understanding your body better but also personalizing the way you handle your symptoms. Because proteins make up multiple components in allergens, we call this type of protein testing allergen component testing.

What we understand as “regular allergy testing” is often whole allergen testing. Whole allergen testing determines whether you have a sensitization to an allergen, but it can’t be used to tell us which specific protein may be causing a reaction.

Allergen component testing tests for certain specific proteins in an allergen that you may be reacting to.6 Discovering the exact protein that you are allergic to could make all the difference for you or your family when it comes to managing your health.

Here are some of the allergies that you can get component testing for:

  • Peanut allergy
  • Tree nut allergy
  • Milk allergy
  • Egg allergy
  • Pet dander allergy (dog, cat, and horse)
  • Alpha-Gal allergy (delayed red meat allergy)
  • Insect venoms (wasp and bee)


When it comes to health, having more information is a never a bad thing. Getting an allergen component test may be the first step toward truly understanding your allergy.

For example, take the story of Frankie, a young boy who was diagnosed at an early age with allergies to tree nuts, peanuts, eggs, dairy, and sesame seeds. Later in life, Frankie’s mother took him to get an allergen component test, and this led to the discovery that Frankie wasn’t allergic to baked forms of milk and egg products but only their fresh forms.

This meant that Frankie had been unnecessarily avoiding milk and eggs and was able to enjoy all baked goods safely. Now, Frankie’s mother can rest easy at the next birthday party when Frankie bites into a cupcake or slice of cake. By getting allergen component tests, Frankie's life and that of his mother's were changed forever.

Understanding you or your family’s allergies on a component level may lead to:

  • Better symptom management
  • Less stress when eating out
  • Developing a more personalized diet
  • More information on which pet is causing an allergy

Allergen component testing is done via specific IgE blood testing, which can be ordered by your healthcare provider.

Specific IgE allergy testing is done by collecting a quick blood sample. The blood is then analyzed in a laboratory for IgE antibodies (the type of antibody your body’s immune system makes when you are allergic to something). Because your blood contains the antibodies to all the specific allergens you may be allergic to, one blood sample may be enough to diagnose multiple types of allergies in one go. Quick, easy, and descriptive.

For more information on allergies or allergen component testing, be sure to check out our Allergy Insider YouTube channel as well as our Allergy Insider webpage on allergy blood testing!

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  1. Ando H, Movérare R, Kondo Y, et al. Utility of ovomucoid-specific IgE concentrations in predicting symptomatic egg allergy. J Allergy Clin Immunol. 2008;122(3):583-588.
  2. Shin M, Han Y, Ahn K. The influence of the time and temperature of heat treatment on the allergenicity of egg white proteins. Allergy Asthma Immunol Res. 2013;5(2):96-101.
  3. Shek LP, Bardina L, Castro R, Sampson HA, Beyer K. Humoral and cellular responses to cow milk proteins in patients with milk induced IgE-mediated and non-IgE-mediated disorders. Allergy. 2005;60(7):912-919.
  4. Nowak-Wegrzyn A, Bloom KA, Sicherer SH, et al. Tolerance to extensively heated milk in children with cow's milk allergy. J Allergy Clin fmmunof. 2008;122(2):342-347.
  5. Schoos AM et al. J Allergy Clin Immunol Pract. 2017 Nov-Dec;5(6):1754-175
  6. Canonica GW, Ansotegui I, Pawankar  R, et al. A WAO – ARIA - GA2 LEN consensus document on molecular-based allergy diagnostics. World Allergy Organ J. 2013;6:17.