Allergies, Intolerances, Sensitivities, And FPIES OH MY!

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There are so many different terms used to describe the reasons people need or choose to avoid certain foods that it can be confusing to understand what it all means. Let’s look at their similarities & differences. 

woman confused about food allergies and intolerances.

I encounter this frequently in practice when patients use the words ‘allergy’ and ‘intolerance’ interchangeably. Frequently, when I am out with my son, who is allergic to eggs, people treat his allergy as an intolerance. In order to understand what the difference is between allergies, intolerances, sensitivities, and FPIES, let’s look at how they are similar and how they’re different.  

This information can be helpful for you in understanding both your own diagnosis and helping others around you understand your needs.

Allergies are different from intolerances and sensitivities in that allergies are the body’s immune system’s response to substances, usually a protein found in food. An intolerance or sensitivity is the body’s inability to properly digest a substance. Allergies trigger an immune system response, which can cause severe reactions, including swelling, difficulty breathing, and death, while intolerances and sensitivities may cause malabsorption and discomfort in the intestines (Food Allergy | AAAAI, n.d.).


In short, allergies are an immune system reaction to a protein that is usually a harmless substance. Allergic reactions can range from mild to anaphylactic (life-threatening). Allergies affect approximately 8 % of children and 4% of adults in the United States (Food Allergies | Healthy Schools | CDC, n.d.; Gupta et al., 2018), and approximately 8.7% of children and 9.5% of adults in Canada self-report a food allergy (2020: Research Related to the Prevalence of Food Allergies and Intolerances – Canada.Ca, n.d.).  

The Canadian Society of Allergy and Clinical Immunology reports that approximately 2% of Canadians are at risk of anaphylaxis from food (Anaphylaxis in Schools & Other Settings, n.d.).  The most common food allergies in Canada and the US are to wheat, triticale, seafood (fish and shellfish), mustard, peanut, tree nut (almond, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios, walnuts), milk, egg, sesame, sulfites, and soy (Allergens and Gluten Sources Labelling – Canada.Ca, n.d.; Anaphylaxis in Schools & Other Settings, n.d.).

It is important to note that the most common allergens, as well as labeling for them, differ regionally.

Oral Allergy Syndrome or Pollen Fruit Syndrome

Oral allergy syndrome is sometimes referred to as pollen fruit syndrome.  It is a reaction in the mouth or throat of a person allergic to latex or pollen after eating raw food with a similarly shaped protein.  Because it is just a similarly shaped protein and not the protein that the person is allergic to, exposure usually just causes itchiness in the mouth and/or throat.  It can, however, occasionally lead to an anaphylactic reaction in those with severe allergies (Oral Allergy Syndrome Symptoms, Diagnosis & Treatment | AAAAI, n.d.).  

Intolerances and Sensitivities

Intolerances and sensitivities involve the intestinal tract, but they do not involve the immune system(Food Intolerance Defined | AAAAI, n.d.). Intolerances may arise from the lack of digestive enzymes required to digest a certain type of food.  

A common intolerance is lactose intolerance.  In lactose intolerance, the intestine does not produce enough of the enzyme known as lactase.  Lactase is required to break down the lactose (a sugar) in dairy products.  Without lactase, lactose doesn’t break down into its 2 component sugars, meaning it’s more difficult to absorb, which leads to intestinal symptoms such as gas, bloating, and diarrhea. 

eggless turtle cake

Baking with food allergies does not need to be frustrating! Even if you can’t use certain ingredients, you can produce amazing desserts that the whole family will love.

While each of these symptoms is unpleasant, it will never be life-threatening (Lactose Intolerance Defined | AAAAI, n.d.). It is important to note that unlike with allergies where you are either allergic or not, there are varying degrees of intolerance.  Some people with lactose intolerance can consume up to 500mL of milk over the course of a day without experiencing symptoms, while others can consume fermented milk products like cheese or yogurt, and others still can only consume very small amounts without experiencing symptoms.

There are several tests you can go for, including a hydrogen breath test, conducted by a gastroenterologist (physician specializing in the digestive tract) to confirm if you are lactose intolerant (Lactose Intolerance | Johns Hopkins Medicine, n.d.).

Celiac Disease

While not everyone with a gluten sensitivity or intolerance has celiac disease, it is important to note that everyone with celiac disease is gluten intolerant. Celiac disease is an autoimmune disorder that causes the lining of the intestine to become swollen and inflamed when exposed to gluten, therefore, decreasing the body’s ability to digest foods and absorb nutrients.  

It is important to note that gluten causes symptoms of intolerance and not allergic reactions. Because gluten does not cause an allergic reaction, exposure to gluten is not life-threatening and is therefore not required to be declared on food labels in the US and Canada, though due to a rise in consumer demand, these rules may change. The only way to confirm a diagnosis of celiac disease is through a blood test followed by an intestinal biopsy conducted by a gastroenterologist (Celiac Disease | NIDDK, n.d.).

Food Protein-Induced Enterocolitis Syndrome or FPIES

Food protein-induced enterocolitis syndrome, or FPIES, is a type of food allergy that involves the immune system but does not include IgE as part of the reaction pathway (see “A closer look at food allergies and oral allergy syndrome”) and affects young children.  

Milk, soy, chicken, turkey, fish, and grains such as rice, barley, and oats are the most common triggers.  When an infant ingests one of these foods, an allergic reaction with severe vomiting, diarrhea, weight loss, and dehydration can occur, leading to a change in body temperature, a drop in energy, failure to thrive, and a significant drop in blood pressure requiring hospitalization.

Children do not experience anaphylaxis from this type of allergy and usually outgrow it by the age of 3-4 years (Food Protein-Induced Enterocolitis (FPIES) | Symptoms & Treatment | ACAAI Public Website, n.d.).

The above information is not intended to replace individual medical advice from your physician and should be used as general information only.


2020: Research Related to the Prevalence of Food Allergies and Intolerances – (n.d.). Retrieved January 6, 2023, from

Allergens and gluten sources labeling – (n.d.). Retrieved January 7, 2023, from

Anaphylaxis in Schools & Other Settings. (n.d.). Retrieved January 6, 2023, from

Celiac Disease | NIDDK. (n.d.). Retrieved January 17, 2023, from

Food Allergies | Healthy Schools | CDC. (n.d.). Retrieved January 6, 2023, from

Food Allergy | AAAAI. (n.d.). Retrieved January 6, 2023, from

Food Intolerance Defined | AAAAI. (n.d.). Retrieved January 6, 2023, from,-Asthma-Immunology-Glossary/Food-Intolerance-Defined

Food Protein-Induced Enterocolitis (FPIES) | Symptoms & Treatment | ACAAI Public Website. (n.d.). Retrieved January 17, 2023, from

Gupta, R. S., Warren, C. M., Smith, B. M., Blumenstock, J. A., Jiang, J., Davis, M. M., & Nadeau, K. C. (2018). The Public Health Impact of Parent-Reported Childhood Food Allergies in the United States. Pediatrics142(6).

Lactose Intolerance | Johns Hopkins Medicine. (n.d.). Retrieved January 17, 2023, from

Lactose intolerance Defined | AAAAI. (n.d.). Retrieved January 6, 2023, from,-Asthma-Immunology-Glossary/Lactose-intolerance-Defined

Oral Allergy Syndrome Symptoms, Diagnosis & Treatment | AAAAI. (n.d.). Retrieved January 6, 2023, from

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