Skip to the main content.

3 min read

IgE vs IgG vs IgA: Decoding Immunoglobulins

 The Difference Between IgE, IgG, and IgA Antibodies

Immunoglobulins, commonly known as antibodies, play a vital role in our immune system. There are various types, including IgE, IgG, and IgA, each with unique functions and immune system responses. Understanding these immunoglobulins and their differences is essential, especially when it comes to addressing food and inhalant immune responses and they are negatively impacting people’s health and overall wellness. In this blog, we'll decode the intricacies of IgE, IgG, and IgA.


Immunoglobulin E or IgE

Immunoglobulin E is associated with immediate hypersensitivity reactions with symptoms arising within minutes to hours of exposure. A way to remember the specifics of IgE is to think E is for emergency as IgE reactions can be sever or even life threatening. IgE reactions also known as allergies to foods and inhalants indicate that those food and inhalant triggers should be avoided completely.


IgE Symptoms:

The most known symptom of an IgE reaction is often anaphylaxis, specifically, swelling of the respiratory tract. IgE can have many other reactions including:

Hives Itchy or Watery eyes
Tingling or itching of the lips, mouth, throat , or ears Swelling of the face: eyes, lips, roof of the mouth
Vomiting Weak pulse
Runny nose/congestion Anxiety
abdominal pain Agitation
Diarrhea Anaphylaxis


Testing for IgE food ALLERGIES:

Testing for food and inhalant allergies can be done via skin prick where a small amount of an allergen is scraped onto the skin where the scraped area is observed for swelling and redness. This is very common and simple to do within office environments but is not the most accurate measurement, can be uncomfortable for patients, and limits the number of allergens that can be tested at a single time.

Blood testing is a more accurate measurement of allergies as it quantifies the specific IgE reaction to each analyte tested. Many blood tests utilize serum collections which allows many markers to be tested at a single time, at US BioTek we can test up to 295 markers, with little to no discomfort for the patient. As technology evolves, we are now able to run blood tests with finger stick microtainer collections and even dried blood spot cards making testing for IgE allergies something patients can do with little to no discomfort from their own home.


Immunoglobulin G or IgG

Immunoglobulin G or IgG, in this case IgG1-3, an antibody that can activate the pro-inflammatory complement system (complement cascade) associated with chronic inflammatory conditions. High levels of IgG (class II or higher) overload receptors and drive the inflammatory reaction while low levels of IgG (class 0/I) indicate tolerance.  

IgG food sensitivity testing is the most commonly performed food sensitivity testing and foods that are only high in IgG can often be safely re-introduced after a period of abstinence. 


IgG Symptoms:

Symptoms of an IgG mediated reactions are often delayed making it challenging to identify the correct culprit. Since symptom are often less sever and, in many cases, chronic, they are often blamed on things like aging. The most common IgG symptoms include:

Bloating Weight Gain
Brain Fog Skin Rash or Eczema
Abdominal Pain Anemia
Diarrhea or Constipation Gas
Headaches Nausea
Fatigue ADD/ADHD
Dry Skin Stress
Joint Pain Anxiety


Testing For IgG Sensitivities:

IgG testing is performed using blood samples to measure the immune response to the analytes tested. There are different testing methodologies that can be used to identify sensitivities, at US BioTek we pioneered the use of Enzyme-Linked Immunosorbent Assay (ELISA). It is now the gold standard in sensitivity testing as it has the largest body of peer reviewed research behind including independent studies that identify ELISA testing as being more accurate with higher rates of reproducibility when compared to other testing methods.

The ELISA method can use serum or dried blood spot cards making it simple to perform anywhere.


Immunoglobulin A or IgA

IgA are present in our mucus membranes and help us fight bacteria and virus pathogens. IgA is an antibody that can also activate the pro-inflammatory complement system associated with chronic inflammation. Unlike Secretory IgA (sIgA) in stool, which is two IgA molecules bounded together and secreted into the gut, serum IgA levels are associated with seasonal allergies and asthma. A Serum IgA reaction (IgA Sensitivities) to food triggers can indicate foods that are irritating the lining of the gut. 


IgA Symptoms:

Chronic Sinus Issues Abdominal Pain/Discomfort
Itchy, Watery Eyes Asthma
Bloating Fatigue
Gas Wheezing
Irritable Bowel Syndrome  Headaches
Irritable Bowel Disease Constipation/Diarrhea


Testing for IgA Sensitivities:

Testing for IgA sensitivities is the same process as IgG sensitivity testing. Often these tests will be run together in tandem providing specific insights into what food and inhalant triggers are causing patients symptoms, and how to create the most efficient treatment plans leading to increased clinical success.



In the intricate world of immunoglobulins, IgG, IgE, and IgA each have their roles in the body's immune responses. Understanding how they impact the body, the timing of reactions, and their relevance in food and inhalant immune responses is essential for healthcare providers. By leveraging this knowledge, practitioners can offer more precise and effective care, ultimately improving patient outcomes.


To learn more about food sensitivity testing and how to build panels specific to your patients needs visit

For more information on Allergy testing, visit


Fecal Zonulin - What does it tell us?

What is Zonulin? Zonulin, used in conjunction with other fecal inflammation markers such as calprotectin, can help clinicians to distinguish between...

Read The Blog
US BioTek & RealTime Join Forces

US BioTek Laboratories Acquire Realtime Laboratories

US BioTek Laboratories Expands Diagnostic Testing Portfolio with Acquisition of Realtime Laboratories US BioTek Laboratories (“US BioTek”), a...

Read The Blog

Infant Allergy & The Maternal Environment

Why do some children have problems with IgE allergy as infants? A history of IgE-mediated allergic disorders in infancy or early childhood...

Read The Blog