Food Intolerances vs. Allergies - What's the Difference?

Food Intolerances vs. Allergies - What's the Difference?

Published on Tuesday, March 21, 2023 by Rebecca Harris

Something is just not sitting well with me. Literally.

I’m sure you’ve heard the age-old tale of being lactose intolerant and sitting down to a delicious plate of mac and cheese and regretting your decision about two hours later. 

When someone offers me mac and cheese, I politely decline and tell them that I’m allergic to dairy. That response usually earns some weird looks.

This begs the question: what is the difference between intolerances and allergies?

In a nutshell (pun intended), a food allergy affects the immune system and a food intolerance affects the digestive system. 

When a person has an allergic reaction, the body defends itself with antibodies called immunoglobulins. In this case, the IgE immunoglobulins answer the call. These reactions may manifest in hives, itchiness, swelling of the skin, or anaphylaxis*. The FDA recognizes eight major food allergens that make up 90% of the United States food-based allergic reactions:

  1. Milk
  2. Eggs
  3. Fish
  4. Shellfish
  5. Tree nuts
  6. Peanuts
  7. Wheat
  8. Soybeans
  9. Sesame (this is a new one!)

When a person experiences a food intolerance, the body struggles to properly digest that particular food item. Diarrhea and vomiting are common symptoms. 

So, how does a person live with a food allergy?

Simple. We avoid our allergens. For me, this means I shrink away from those scrumptious slices of four-cheese pizza. Is it annoying at times? Yes, very. But in an effort to stay healthy, I need to make those choices.

How does a person live with a food intolerance?

Avoiding the food item would be ideal, but let’s face it. You want that ice cream sundae. Luckily, when you have a food intolerance, you can eat small amounts of the food item without experiencing negative side effects. There are also over-the-counter medications available to ease discomfort (ex. Lactaid for lactose intolerance).

Do food intolerances impact any other gastroenterological diseases?

Yes! In some cases, sensations that may feel like acid reflux (gas, belching, heartburn, indigestion) can be caused by food intolerance. Unfortunately, it may be difficult to differentiate between the two, so talk to your medical provider for more guidance.

Additionally, studies have shown a connection between food intolerances and IBS (irritable bowel syndrome). Up to 65% of people with IBS report that their symptoms are related to specific foods.

Whether you have a food allergy or intolerance, it is important to acknowledge the effects of the food on your system. If you have an allergic reaction, especially anaphylaxis, seek medical attention immediately. If you have a food intolerance, try an alternative food option. If you have any questions, be sure to speak with a medical professional.

*Anaphylaxis is a serious reaction that causes difficulty breathing, dizziness, and loss of consciousness. If untreated, it can be deadly. Learn more about anaphylaxis from the American College of Allergy, Asthma, and Immunology.

Looking for more information?

Try these helpful websites:

FARE (Food Allergy Research & Education) - provides numerous resources on food allergies including:

  • How to recognize and respond to an allergic reaction
  • How to read a food label 
  • Food allergy misconceptions and myths

APFED (American Partnership for Eosinophilic Disorders) - provides strategies for people that live with food allergies every day

FAACT (Food Allergy and Anaphylaxis Connection Team) - provides information for people that have anaphylactic reactions to certain food items


  1. AAAI. (2020). Food intolerance versus food allergy, American Academy of Allergy Asthma & Immunology,
  2. Choung, R. and Talley, N. (2006). Food allergy and intolerance in IBS, Gastroenterology and Hepatology, 2(10), 756-760, 
  3. Functional Gut Clinic (2017). Food intolerance and acid reflux, Education - Gut Health Blog,
  4. Li, J. (2022). Food allergy vs food intolerance: What’s the difference?, Mayo Clinic, 
  5. FDA. 2022. Food allergies: what you need to know, U.S. Food and Drug Administration,


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