IgE and Allergies: 5 facts you need to know

Dr. Momma discusses how IgE and allergies are the real allergy disease most of us think about and shares insightful information about how the problems occur

IgE  and allergies are words that often are discussed hand-in hand.  “IgE allergy” is a specific disease process and is NOT an intolerance. My previous blog post discussed food allergies compared to food intolerances.  When doctors evaluate allergies, they frequently measure IgE; however, people do not know what IgE is!

Let’s start with some basics. “Ig” is an abbreviation for Immunoglobulins (Imm-YOU-no-GLOB-you-LINS).  We do not pronounce “Ig” like we learned in school; we simply say the letters separately: I–G.

Immunoglobulins are antibodies made by our immune systems to fight foreign substances. Some of the things that our immunoglobulins (antibodies) attack include bacteria, viruses, fungus, animal dander, pollen, medications or cancer cells.


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Antibodies react only to a specific foreign substance. For instance, antibodies for the flu virus do not fight the virus that causes chicken pox. We need immunoglobulins because if we do not make enough, we suffer from repeated infections.

We also make immunoglobulins (antibodies) which cause allergies, and sometimes we make antibodies that attack our own normal tissues. When this happens, an Autoimmune Disease occurs. Although most of our antibodies fight to keep our bodies strong, sometimes the antibodies we make lead to additional disease.

The 5 major classes of Immunoglobulins include:

  1. IgA: These antibodies, found on areas with a lining that produces mucous,  protect surfaces of our body that are directly exposed to outside foreign substances. Examples include: ears, eyes, nose, throat, lungs, and stomach.
  2. IgG: These antibodies, found in all parts of our body, fight bacteria and viruses as well as other foreign substances on a daily basis. Although the smallest sized immunoglobulin, they represent 80% of the antibodies that we make.
  3. IgM: These antibodies, found in the blood and lymph fluid, respond to infections first and begin the process of protecting our bodies while other antibodies are being produced.
  4. IgE: These antibodies, found in the skin, lung and in areas with a lining that produces mucous, trigger the well known allergic reactions.
  5. IgD: Rarely talked about because it is not clear what they do!

So now you understand that IgE and allergies remain linked together because the Immunoglobulin E causes the allergic reactions.

5 facts you need to know about IgE and allergies:

1. Blood testing measures the amount of IgE in the blood

Traditional blood allergy testing measures amounts of IgE; however, people with no allergic disease show minimal amounts of IgE. This test serves as a marker that allergic disease is present, but should be combined with further history, examinations and testing for a more accurate diagnosis.

Some doctors measure the amounts of IgG, but this test fails to evaluate true allergy disease. IgE and allergies remain linked while IgG reactions represent an intolerance.

2. Skin testing measures the amount of IgE in the skin

The skin represents a major area for IgE to collect; therefore, one of the best ways to determine allergy severity includes performing skin prick testing. A small amount of the suspected allergen (food, pollen, dust, mold etc) is placed just under the skin while monitoring reactions. A red area around the site may develop, but the amount of swelling that occurs is most important.

 3. Allergies run in families

Genetics plays a large role in developing allergies. For children, if only one parent has allergies of any type, a 25-40% chance exists that allergies will develop. If both parents have allergies, a  70-90% chance now exists that their children will have allergies. The specific allergy type is not passed on, just the likelihood of developing some type of allergy

4. The allergy reaction releases a chemical called histamine

Once IgE forms, it triggers a special series of steps leading to an allergic reaction. These immunoglobulins move through the body and interact with cells that release histamine. (HIS-tuh-MEEN).

Histamine is the chemical that causes many of the symptoms that we associate with allergies, so it makes sense why we treat our symptoms with medications that are called ANTI-histamines. We really need that histamine to stop doing the ugly things that lead to our allergy symptoms!

5. IgE is the root cause of common allergy diseases

This immunoglobulin plays a major role in the development of allergic asthma, allergic nasal disease, most types of sinusitis, food allergies, hives and chronic allergic skin rashes. It is also the key agent in developing severe reactions to medications and bee stings that require the use of an Epi-pen injection.

IgE and allergies represent the disease that many of us think about with true allergic disease. Although not exactly the same, feel free to use terms IgE and allergy interchangeably!


Dr. Momma discusses how IgE and allergies are the real allergy disease most of us think about and shares insightful information about how the problems occur

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Caitlin @RogersPartyof5

This was so interesting to me. I also loved your post on food intolerance vs food allergies. I’m so glad I stumbled across your blog! It is packed full of great information.

    Momma Addict

    I am so glade you are here. I am trying to roll out small pieces of allergy information at a time so it is not so overwhelming. But I think that as people understand exactly what is happening, they can better managed them. Many of my patients don’t use medications correctly because they do not understand the disease.

Michelle Kujawa

Allergies suck! I understand this personally. I have food allergies, medication allergies, and airborne allergies. My son has food allergies and airborne allergies. Our Epi Pens are never far from us. It sucks having to carry them around but our very lives depend on it.
Michelle/ Life of an Imperfect Mom

    Momma Addict

    Yes, food allergies are actually the worst because there is not real treatment. EXCEPT, many people with food allergies are improved when their other allergies are better controlled. Even if you think the grass and tree allergies are not bad, they are impact the immune system. Some people note reduced food allergy reactions after getting on appropriate medications, using saline washes and starting allergy shot for outdoor allergies. Might be something to discuss with your allergist.


Wow, great information. Thanks for sharing this!

Debra Rodriguez

When you or a family member has a food allergy, you resign yourself to the realization that there is no cure. Though the solution seems simple eliminate the food that you are allergic to that’s anything but simple in our fast-paced lives of eating packaged and restaurant foods.

    Momma Addict

    You are correct that there is not cure. However there are many things that reduce the impact. One of them is to control the other allergies in your life that you may think are not bad. By using medications, saline washes and/or allergy shots, you “down regulate” the immune system which makes the reactions less severe. If your allergy mechanism is not running full speed, the reactions to some food allergies improved in some people. You might consider talking to your doctor about the other allergies and see if there is any work that can be done there.


I had a lot of trouble with my first born relating to intolerances and I wish I had read this, I felt often I was his only advocate and if I only knew more then I could have prevented a lot of discomfort through our trials!

    Momma Addict

    I am so sorry you had such a hard time. Many people also worry and intolerance will progress to life threatening allergy reactions. I am hopeful that my upcoming posts sharing more information about allergy and other ENT issues will be beneficial to people.Thanks for reading!

Liz F.

I never knew the science behind allergies. This is a comprehensive list that explains a lot. I didn’t know allergies run in families.


Such a great informative information about ig! I didn’t know any of this but this would definitely help with allergies by know it! Especially the different types! Didn’t know there were so many!

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