Medically reviewed on June 14, 2022 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
When you have a food allergy, it can often be clear that you have it. But if you’re faced with an itchy throat hours after eating, it can be hard to link your symptoms with a particular food.
That’s when knowing the difference between an IgG or an IgE test can help.
Both IgG and IgE antibody levels indicate a negative reaction to foods. However, there are a few key differences between these two reactions. For greater visibility regarding possible food sensitivities or allergies, read our IgG vs IgE guide below (and for IgG testing try the Everlywell Food Sensitivity Test or the Food Allergy Test for IgE allergy testing).
Before explaining the differences, let’s discuss exactly what IgG and IgE are—protective antibodies.
When the body judges a foreign substance as dangerous, the immune system fights back just as if it was fighting an illness.
The body’s weapon of choice? Antibodies, also known as proteins called immunoglobulins.
Depending on the severity of the reaction, different immunoglobulins are used. The body’s three food-related immunoglobulins include :
IgE and IgG tests could be the key to unlocking what foods may be behind food allergies or sensitivities.
If you’re facing stomach grumbles and eczema at inconsistent times, you might be experiencing IgG attacks—also known as a food sensitivity.
Experts believe that a “leaky gut” (or microscopic tears in the small intestine) may lie at the heart of food sensitivities and IgG responses . Tiny intestinal holes may allow food particles to cross into the bloodstream, triggering digestive issues. The result? A delayed IgG secondary immune response with shifty gastrointestinal symptoms.
According to research, about 5–20% of all people have an IgG-related food issue . Let’s explore the typical signs of an IgG reaction.
The easiest way to identify an IgG-related food sensitivity? The symptoms.
Compared to an allergic reaction, IgG responses are usually delayed, dose-dependent, and stomach-related. An IgG reaction arrives anywhere from a few hours to three days after ingesting a trigger food . However, that doesn’t make food sensitivities any less bothersome.
If you suspect you may have a food sensitivity, consider taking the Everlywell at-home Food Sensitivity Test.
At the end of the day, almost any food can trigger a sensitive reaction—it all depends on your unique biological system. But for most people, these foods are the common culprits behind any IgG-related intolerances :
To discover food sensitivity triggers, an IgG blood test can point the way. After receiving the results, it’s time to try an elimination diet. In other words, you can try eliminating and slowly reintroducing a portion of food to your plate. This step can help determine if that food is truly the cause of an IgG-related food sensitivity.
Immediate hives? Instant rashes? Difficulty breathing after eating? Any of these food allergy symptoms could signal that you’re facing an IgE immune response.
IgE antibodies are the body’s primary immune response against a foreign substance. When the immune system sees an ingested, inhaled, or even touched substance as a threat, it will quickly send IgE antibodies to trigger a direct allergic reaction. Usually, this reaction is more severe and more immediate than symptoms that occur with food sensitivities.
Severe allergies tend to be obvious—they’re usually debilitating or even fatal. But when symptoms are mild, it can be tough to determine if they are a sensitivity or an allergy. That’s when inspecting for common IgE reaction symptoms can help :
There’s crossovers between allergy-causing foods and foods that provoke a degree of sensitivity. However, allergic reactions also include non-food substances—everything from cat hair to dust.
When taking an IgE test, here are the most common allergies that may trigger a reaction :
In general, it’s best to avoid any substance that may have been revealed as triggering your IgE levels, but be sure to talk about this with your healthcare provider. With time and proper health maintenance, you may be able to decrease the severity of your body’s IgE response to a certain substance .
Everlywell offers several IgG and IgE testing options, with sample collection done from the convenience of home:
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8. How You Can Eliminate a Food Allergy. University Hospitals. URL. Accessed June 14, 2022.