IgG vs. IgE Antibodies: Understanding the Differences

IgG and IgE antibodies are both part of the immune system, but they are associated with different types of food-related reactions. IgE reactions are typically linked to immediate food allergies, while IgG responses may be associated with delayed food sensitivities.

The three primary food-related immunoglobulins include[1]:

• Immunoglobulin E (IgE) – An antibody involved in rapid immune responses, including food allergies
• Immunoglobulin G (IgG) – An antibody associated with delayed immune responses that may occur after eating certain foods
• Immunoglobulin A (IgA) – An antibody that helps support immune function in mucous membranes, including those in the digestive tract

Understanding the differences between IgE and IgG responses may provide additional insight into how your body reacts to certain foods.

Category	IgG	IgE
What it may indicate	A possible delayed food sensitivity response	A possible immediate food allergy response
Typical timing	Symptoms may appear hours or even days after eating a food	Symptoms often appear quickly after exposure to a food
Common symptoms	May include bloating, headaches, fatigue, or digestive discomfort	May include hives, swelling, itching, wheezing, or anaphylaxis
Best used for	Exploring possible food sensitivities	Helping identify potential food allergies

If you experience symptoms like stomach discomfort, bloating, headaches, or fatigue after eating—but can't pinpoint the cause—you may be dealing with a food sensitivity.

Unlike food allergies, which tend to trigger immediate immune responses, food sensitivities are often associated with delayed reactions that can appear hours or even days after eating certain foods. While researchers are still studying the exact mechanisms behind food sensitivities, IgG antibodies are believed to play a role in some of these immune responses.

Here's a closer look at common IgG-related symptoms and the foods most often associated with these reactions.

IgG symptoms

One of the most noticeable signs of a potential IgG-related food sensitivity is recurring symptoms that seem difficult to explain or predict.

Because IgG-related immune responses tend to develop more slowly than food allergy reactions, symptoms may not appear immediately after eating.[2] This delayed timing can sometimes make it harder to identify trigger foods.

Common symptoms associated with food sensitivities may include:

• Bloating
• Stomach discomfort
• Headaches
• Fatigue
• Brain fog
• Changes in bowel habits

If you suspect certain foods may be contributing to your symptoms, consider taking the Everlywell at-home Food Sensitivity Test.

Common foods for IgG testing

Food sensitivities can vary widely from person to person, and nearly any food has the potential to trigger symptoms in sensitive individuals. However, some foods are more commonly associated with IgG-related reactions than others.[3]

• Coffee
• Corn
• Dairy products
• Eggs
• Gluten-containing foods
• Peanuts
• Shellfish
• Soy
• Yeast

An IgG blood test may help identify foods worth evaluating further as part of an elimination diet approach. After reviewing your results, you can consider temporarily removing certain foods and then slowly reintroducing them one at a time to monitor how your body responds. This process may help you better identify foods that could be contributing to ongoing symptoms.

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.

IgE symptoms

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 [4]:

• Breathing issues (wheezing, heavy breathing, triggered asthma)
• Skin inflammation (hives, eczema)
• Swollen facial tissue, tongue, or limbs
• Mouth tingles or itches
• Nasal drip or congestion
• Digestive issues (cramps, diarrhea, vomiting)
• Dizziness and lightheadedness
• Anaphylaxis (potentially fatal body system shutdown)

Common substances for IgE testing

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 [5]:

• Pollen
• Peanuts
• Tree nuts (walnuts, almonds, etc.)
• Shellfish
• Animal dander
• Insect bites or stings
• Dust mites

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 [6].

If you think certain foods may be contributing to uncomfortable symptoms, it may help to speak with a healthcare provider. They can evaluate whether your symptoms could be related to a food allergy, food sensitivity, or another underlying condition and help guide appropriate testing and next steps.

Everlywell offers convenient at-home testing options designed to help you better understand how your body responds to certain foods—all with sample collection completed from home:

• Food Sensitivity Test – Measures IgG reactivity to 96 commonly consumed foods and ingredients to help support an elimination diet approach
• Food Sensitivity Comprehensive Test – Measures IgG reactivity to 204 foods and ingredients for a more expansive look at potential food sensitivities

Learning more about your body’s unique responses may help you make more informed decisions about your diet, symptom management, and overall wellness.