Skip to main content

Clearing up the confusion around food allergy, intolerance, and sensitivity

Slices of bread with faces cut into them

read time: 4


Health & Wellness, Nutrition

So, you think you or your child has an allergy to a food. You type it into your search bar and dozens of articles pop up mentioning food allergy, intolerance, and sensitivity. What’s the difference? Don’t they all mean the same thing? Let's clear up the confusion around these common terms and define what each means. We’ll also explore how testing can help clarify your diagnosis.

Let’s break it down: food allergy vs food intolerance vs food sensitivity

Popular culture would lead you to believe these words could be used interchangeably, but not so. A true allergy only happens in 10% of children and roughly 5% of adults. Other bad reactions people experience from food are more likely intolerances or sensitivities. Here’s some clarity on what each term means, and how your body reacts:


Food allergy: an immune reaction + antibodies

True food allergies stem from your body’s abnormal immune response to a substance that wouldn’t ordinarily be considered dangerous. Food is broken down during digestion, and the pieces are absorbed in the intestine, usually without creating any alarm. In some individuals, however, the immune system reacts to the food substance releasing a troop of antibodies called immunoglobulin E (IgE).1 These bind to the surface of cells that line the intestine, as well as the skin and respiratory tract, as if they were guarding the body against a return attack. Once the food re-enters the system, it stimulates IgE antibody-coated cells to release histamines, which cause inflammation. The inflammation leads to physical reactions such as coughing, vomiting, diarrhea, itching, sneezing, and more. An allergic reaction can be severe enough to be life-threatening.

This process tells us that a medical diagnosis of allergy requires 2 things:

  • • A positive test for IgE antibodies against the suspected food allergen
  • • An abnormal reaction in your immune system when exposed to it
Person itching their arm

Food intolerance: a reaction, but not an allergic one

Unlike a food allergy, food intolerance is a non-immune reaction to food. It could be something in the food which would affect anybody, such as a toxin or a chemical. A reaction could also occur and affect only certain people because of their body’s unique metabolic makeup, such as lactose intolerance.2 People with lactose intolerance lack the enzyme required to break down lactose into smaller, more absorbable sugars. Too much lactose enters the colon and causes bloating, gas, and diarrhea. Lactose intolerance is not immune-related, so it isn’t categorized as an allergy.
Block of swiss cheese

Food sensitivity: no reaction, not an allergy

You might have heard sensitivity used quite a bit as you searched for answers. Let’s be clear: food sensitivity is different from an allergy. Allergists make a clear distinction between sensitivity, or what is usually called “sensitization,” and allergy. They consider someone “sensitized” to a substance if they have IgE antibodies against the food. Still, they do not have an immune-related reaction when they are exposed to it.

Remember: sensitization only becomes an allergy when, besides having the presence of IgE antibodies, you also have an abnormal immune-related physical response to the food allergen.
Woman holding her stomach

Our body’s mystifying IgE antibodies

Researchers are still trying to determine why IgE antibodies, or having a sensitization, may or may not trigger allergic reactions. For example:

  • Higher levels of IgE antibodies for a specific food sometimes, but not always, put you at higher risk for allergies
  • It’s possible to be sensitized, having IgE antibodies, without an immune-related reaction, and then develop an allergy later in life
  • The same can be said for the opposite—an allergy may disappear later in life, but you can still have IgE antibodies in your body

Deconstructing gluten-related disorders

Here’s a popular topic regarding food—gluten. It’s to blame for a wheat allergy, gluten intolerance, celiac disease, and gluten sensitivity. All have similar symptoms but are very different in how they impact the body.

A wheat allergy3 (or a grain allergy) is like any other food allergy. IgE antibodies storm against gliadin proteins in gluten and activate an abnormal immune response when the person eats wheat products. Gastrointestinal symptoms such as abdominal pain or diarrhea occur within a few minutes to a few hours after ingestion.

Gluten intolerance has similar symptoms to a wheat allergy and usually occur hours to days after ingestion. Still, the patient does not have any IgE antibodies against the gliadins. The cause of gluten intolerance is unclear.

Celiac disease4 is a chronic auto-immune disease triggered by gluten. People with celiac disease have a completely different response when exposed to gluten. Their T-cells, a white blood cell, cause inflammation and damage the bowel lining. Celiac disease does cause an abnormal immune response. However, it does not involve the presence of IgE antibodies, so this rules it out as an allergy.

Woman looking at a jar in a shop
Quick Fact
Every person reacts differently. Listen to your body—if you feel bad, it’s time to discover the reason why.

Pay attention to your symptoms

Allergic reactions to food can be mild to severe. Skin reactions are the most common and range from an itchy red rash to small bumps called hives. A reaction involving deeper layers of the skin can create swollen red areas, known as angioedema, on any part of your body. Abdominal pain, vomiting, and diarrhea are typical gastrointestinal symptoms of food allergy. Less common symptoms in the respiratory tract range from congestion to breathing difficulty. The most severe form of reaction, which can include all 3 organ systems and the cardiovascular system, is called anaphylaxis.5 All of these reactions must occur soon after exposure to the suspected food allergen to be considered related to true food allergy.

When you suspect a food allergy or sensitivity

It's best to make an appointment with your doctor or allergist, especially if you suspect a true food allergy. The only way to definitively diagnose a food allergy is with a thorough investigation of your medical history, including your symptoms and reactions, and more comprehensive testing to see if you test positive for IgE antibodies for a specific food. There are a few different testing types available that your doctor might recommend:

Avoid triggering foods

Many people may stop eating foods that make them uncomfortable and never feel the need to be diagnosed. However, even "elimination diets" should be discussed with a doctor or dietitian.

At-home food sensitivity tests

It’s human nature to want to find a quick cure when we don’t feel well. At-home food sensitivity tests might seem quick and easy to determine what foods might trigger symptoms. These usually test for IgG antibodies6 and claim to be able to identify hundreds of foods that might cause symptoms in your body. It is important to note that these tests are not designed to detect IgE antibodies, which can indicate sensitization. Many professional medical organizations and associations advise against using them because they are not scientifically proven and may lead to inaccurate results.

If you're uncertain, get tested

It is easy to confuse allergies, intolerances, and sensitivity, as they all make you feel unwell. Self-diagnosis may seem like the answer, but if you want to find the real cause, you should talk to your doctor and get tested.


1 Immunoglobulin E (IgE) defined.
American Academy of Allergy Asthma & Immunology. Accessed November 7, 2022.,-asthma-immunology-glossary/immunoglobulin-e-(ige)-defined

2 Lactose intolerance.
National Institute of Diabetes and Digestive and Kidney Diseases, U.S. Department of Health and Human Services. Accessed: November 4, 2022.

3 Wheat & gluten allergy: Symptoms & treatment. ACAAI Public Website. Published April 13, 2022. Accessed November 7, 2022.

4 Celiac disease, non-celiac gluten sensitivity, and food allergy: How are they different?
American Academy of Allergy Asthma & Immunology. Reviewed May 11, 2022. Accessed November 7, 2022.

5 Anaphylaxis: Causes, symptoms & treatment.
ACAAI Public Website. Published April 14, 2022. Accessed November 7, 2022.

6 The myth of IGG food panel testing.
American Academy of Allergy Asthma & Immunology. Reviewed September 28, 2020. Accessed November 7, 2022.

Page Published: June 14, 2023

The Quest Editorial Team

Follow Quest on social

We translate your health, so you can transform it. 


Buy your own lab tests

Shop online for food allergy tests - no doctor visit required for purchase