Food Allergy Versus Food Intolerance

March 15, 2019 

Food allergies and food intolerances have many similar symptoms, so it’s understandable that many people wrongfully self-diagnose. But a food allergy is different from a food intolerance, and knowing exactly which one you have could save your life—and give you peace of mind.

To help you figure out the difference, here’s some food for thought.  

What is a food allergy?

Food allergies are the body’s immune system reacting to something that is normally harmless to most people, such as the proteins in milk, eggs, or nuts. They’re particularly prevalent among children, affecting one in every 13 kids. That’s about two kids in every classroom. What’s more, a food allergy reaction sends someone to the emergency room every three minutes.1

How do you know if you might be allergic to something you ate? When caused by a food allergy, symptoms typically happen within minutes of ingesting the food. These common symptoms include: 

  • Stomach pain
  • Diarrhea
  • Nausea
  • Intense itching
  • Swelling of the face  
  • Rash/hives
  • Increased anxiety
  • Light headedness/dizziness
  • Vomiting
  • Anaphylaxis

And although more than 170 foods have been reported to cause allergic reactions, the most common culprits are:2

  • Eggs
  • Milk
  • Peanuts
  • Tree nuts
  • Wheat
  • Soy
  • Fish and shellfish

Food Allergy or Food Intolerance?

Is it food allergy or food intolerance? It's vital to know what your underlying allergic triggers are so you can be confident with your food choices and take control of your symptoms.

What is a food intolerance?

Have you ever had an upset stomach or felt nauseated after eating certain foods? It could be an intolerance. A food intolerance, or sensitivity, happens when you experience difficulty digesting a particular food. It’s estimated that up to 20 percent of the world’s population may have a food intolerance.3

While food allergies mainly involve the immune system, a food intolerance mainly involves the digestive system. Symptoms of food intolerance can be delayed by up to 48 hours and last a long time, making the offending food especially difficult to pinpoint.3 Similar to food allergies, common symptoms include:

  • Nausea
  • Fatigue
  • Rashes3

Lactose, wheat, gluten, caffeine, and additives such as artificial sweeteners, coloring, and other flavorings are some common types of food intolerance.4

When it comes to gluten, many people have unpleasant symptoms even when they test negative for celiac disease. This is known as non-celiac gluten sensitivity (NCGS), which has been estimated to impact anywhere from 0.5 to 13 percent of the population.3 NCGS is often defined by what it’s not: It is not an allergic reaction such as a wheat allergy, and it’s not an autoimmune reaction such as celiac disease, either.

Chances are, you’ve experienced an unwelcome reaction to eating a particular food or even avoided certain foods altogether because of the subsequent symptoms that occur. The next step is to find out if it’s truly an allergy or an intolerance.

How can you tell if you have a food allergy or intolerance—and why does it matter?

With similar and overlapping symptoms, such as stomach pain and nausea for example, it can be difficult to identify the cause of your problem. But it’s a really important distinction to make because if you have a food allergy, your reaction can be severe and even life-threatening, even after coming into contact with only a tiny amount of the food. While a food intolerance can be a major inconvenience, it’s not as serious as food allergy.

The first step in managing symptoms is seeking appropriate care. Talk to your healthcare provider about your history and symptoms. Then, testing can come into play. You can learn more about the different types of allergy testing here. Once you have a clear picture of what could be causing symptoms, you and your healthcare provider can create an appropriate management plan that will likely include ways to avoid certain triggers.

Getting to the bottom of your food allergy or food intolerance symptoms may seem tricky and at times frustrating, due to overlapping symptoms, timing of reactions, and other foods encountered after ingesting a trigger food. But remember that you are not alone in the world of food allergy and intolerance. Talk to your healthcare provider about your experiences and know your testing options. With the right test and management plan, you’ll be well on your way to relief.  

Tools for Understanding Allergies


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  2. Boyce J, et al. Guidelines for the diagnosis and management of food allergy in the United States: Report of the NIAID-sponsored expert panel. J Allergy Clin Immunol. 2010; 126(6):S1-58.