What is the difference between a food sensitivity, food intolerance and food allergy?

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I get asked a lot about the differences between a food allergy, intolerance, and sensitivity. Personally, I don’t have any food allergies, I may have some intolerances, and definitely have food sensitivities. Understanding the foods my body is sensitive to was one of the first steps on my path to feeling better. I hope that this article helps you understand the difference between them and their symptoms. Then, you can start taking steps to feel better, too.

Understanding the Definitions of Sensitivity, Intolerance, and Allergy

Photo of woman sneezing with tissue

The definitions of food allergies and intolerances have been established by the American Association of Allergy Asthma and Immunology. There isn’t an established definition of the term food sensitivity.

When talking with someone about these issues, being sure you are using the right term will help them understand which issue you’re dealing with. Being precise will help you and those who are helping you deal with it be on the same page.

Food Sensitivities

Unlike food intolerances, food sensitivities do involve the immune system but do not involve as severe a reaction as a food allergy. Food sensitivities happen when your immune system reacts to a particular food. The reaction in your body to the food may not necessarily seem to be related to the food.

What are the symptoms of a food sensitivity?

There are two things that make food sensitivities hard to track down:

  1. Symptoms are diverse
  2. Symptoms can take up to three days to show up

Food sensitivity symptoms are common in those with IBS and can include gut issues including gas, bloating, diarrhea, or constipation – or all of these!

Symptoms can also include:

  • GERD
  • Migraines
  • Muscle aches
  • Joint aches
  • Brain fog
  • Fatigue

What are the typical foods people are sensitive to?

Just about any food can cause a food sensitivity reaction. You may have heard of non-Celiac gluten sensitivity. This is where someone has digestive problems from gluten similar to someone who has Celiac disease (but has tested negative for Celiac disease).

How do you test for food sensitivity?

There is no “gold standard” for food sensitivity testing. And, there are a lot of food sensitivity tests on the market. I use Mediator Release Testing (MRT).

What do you do if you have a food sensitivity?

The only thing you can do when you have a food sensitivity is to avoid the food. Food sensitivities are often part of a larger issue with your gut. Addressing the underlying issue, like leaky gut or inflammation in the digestive tract, may get rid of your food sensitivities.

Food Intolerances

Whereas a food allergy involves the immune system, food intolerance is when you have difficulty digesting a particular food. Food intolerance reactions involve the digestive system only.

What are the symptoms of food intolerance?

The typical symptoms of food intolerance include digestive or GI issues including gas, bloating, diarrhea, or constipation.

What are the typical foods that cause intolerance?

One of the most common foods to be intolerant to is lactose, which is a sugar found in dairy products. If you are lactose intolerant, you are missing the enzyme lactase that is needed to break down lactose.

Other foods that can cause intolerance include:

  • Beans, lentils, and legumes
  • Chocolate
  • Eggs
  • Food additives
  • Strawberries
  • Citrus fruits
  • Tomatoes
  • Wine, particularly red wine
  • Histamines in foods

How do you test for food intolerance?

Since the issue with food intolerance is in the digestive system, there isn’t a good way to test for it. The best way to determine if food intolerance is causing your digestive problems is to track your food and see if there is a pattern to what you eat and your symptoms.

If you tracking your food and symptoms doesn’t shed any light on which food(s) may be causing the problems, an elimination diet is a good next step. You can follow a basic diet for a minimum of two weeks then start adding in foods. You’ll need to keep tracking your food and symptoms to be aware of when your symptoms happen and which food you added in.

Another set of foods that can cause symptoms based on an intolerance are FODMAP-containing foods. If you’re wondering what FODMAP-containing foods are, you can read about What’s a FODMAP and why do I care?

What do you do if you have a food intolerance?

Just like with an allergy, if your body doesn’t have what it needs to digest the food, you can avoid it. If you don’t eat the food, then you won’t have the symptoms.

Another option is to use digestive enzymes. If lactose is your issue, then you can take Lactaid when you eat or drink milk products. Lactaid also produces milk that has the lactose broken down.

If beans, lentils, or legumes cause you problems, a product like Beano can help. Take it as directed when you eat these foods.

Food Allergies

A true food allergy is when your immune system overreacts to a protein found in a particular food. Even small amounts of that food can cause a reaction. The symptoms of a food allergy can range from a mild allergic reaction to one that is life-threatening.

What are the symptoms of an allergic reaction to food?

Typical symptoms of allergic reactions to food include:

  • Tingling or itching of the mouth, lips, or tongue
  • Hives, itching, or eczema on the body
  • Swelling of the lips, tongue, throat, face, or other parts of the body
  • Nasal congestion, wheezing, or difficulty breathing
  • Abdominal pain, nausea, vomiting, or diarrhea
  • Lightheadedness, dizziness, or fainting

Some people can have an anaphylactic response which is life-threatening. If you have an anaphylactic response, you should seek medical attention.

Symptoms of an anaphylactic response include:

  • Tightening or constriction of the airways (this can include tongue swelling)
  • Swelling in the throat
  • Feeling like there is a lump in the throat that makes it difficult to swallow
  • Increased pulse rate
  • Lightheadedness, dizziness, or loss of consciousness

If you experience symptoms of a food allergy, they may become more severe when you eat that food again in the future.

What are the typical foods that cause allergic reactions?

Food allergies are triggered by the proteins in foods. The most common food allergies are to:

  • Shellfish (e.g. shrimp, lobster, and crab)
  • Peanuts
  • Tree nuts (e.g. walnuts, pecans)
  • Fish
  • Eggs
  • Cow’s milk and cow’s dairy products including cheese, yogurt, cottage cheese, casein, and whey
  • Wheat (a food allergy is different from Celiac disease)
  • Soy

How do you test for a food allergy?

There are a variety of ways to test for a food allergy. They include:

  • Oral challenge
  • Elimination diet
  • Skin prick test
  • Blood test

Testing for a food allergy should be done under the supervision of a medical practitioner such as an allergist.

What do you do if you have a food allergy?

The only thing to do when you have a food allergy is to avoid the offending food. You should also ask servers at restaurants about food preparation especially if shellfish or fish is the food you react to. This is because the restaurant may be using a fish or shellfish stock in surprising places.

You will also want to talk with your doctor about getting an EpiPen to carry with you at all times.

Still Not Sure?

If you’re still not sure if you have an allergy, intolerance or sensitivity, you might want to check out this article on the 5 Steps to Restore Gut Health.

If you want to go gluten free and dairy free and see if those two food categories are causing your problems you can download my free guide, Easy Gluten Free and Dairy Free Meals for Every Day of the Week. In the guide, I talk about why going gluten free and dairy free can help you feel better. It also has simple, easy, and tasty meal ideas that make trying out this new way of eating do-able.

This article was originally published on September 8, 2016. It was revised and republished on March 26, 2019.

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Dr. Penny



My goal is help you take control of your triggers so you can lead a normal life. I’ve had Irritable Bowel Syndrome for over 14 years. I’ve been told, “It’s all in your head.” And, “You just need to figure out what’s causing your symptoms” without being provided any help to figure it out. I’ve finally gotten my symptoms under control. I want to help you do the same thing. I want to help you get your life back.


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