Food Allergies vs. Food Intolerance vs. Food Sensitivity: Identifying Your Reaction

By Megan Pennington (bio below)

These days it seems everyone has experienced some kind of reaction to food. Whether it manifests as a simple bout of indigestion, or a chronic condition like eczema, we now know that food reactions play a major role in inflammation and related disease. But did you know that it’s important to know whether your reaction is due to food allergies vs food intolerance vs food sensitivity?

What are the different types of adverse food reactions?

Food Allergies vs Food Intolerance vs Food Sensitivities

Let’s say your child has a rash or constant runny nose, and you wonder if maybe its food related. Dairy, gluten, grains, sugar?? What’s really going on here? All food reactions can basically be divided into 3 main categories:

Food Allergy

This is called a type 1 hypersensitivity, whereby the immune system identifies some component of a food as dangerous, and produces the IgE antibody against it. When the food is eaten,  IgE antibodies bind to mast cells (located in body tissues) and cause these to “explode” and release large amounts of histamine into the body’s tissue.

Symptoms of a Food Allergy:  Generally an allergic reaction (type 1 hypersensitivity as mentioned above) will be quick (within 45 minutes of exposure), and cause obvious symptoms related to the sinuses, airways, or skin (sneezing, itchy eyes, rash, swelling, or bronchial constriction). These symptoms will gradually subside once the allergen is removed in mild cases. But in moderate to severe cases and anaphylaxis, where multiple bodily functions are affected, emergency treatment with epinephrine is necessary.


Related Post: It’s Just Not Worth The Risk: Our Anaphylaxis Experience


Food Sensitivity

These include type 2, 3, and 4 hypersensitivities. These differ from type 1 (allergy) in that they cause the release of mediators (like histamine) into the blood instead of into the body’s tissues. This is important because it means that the reaction will be delayed and produce less obvious symptoms.

Type 2 reactions are mediated by IgG antibodies and IgM antibodies. Type 3 reactions describe a situation where a food antigen and antibody complex is formed. Type 4 does not involve antibodies at all, but instead is a direct antigen to cell reaction. Regardless of the mechanism, the end result is the same:  the immune cells are triggered to release mediators (immune chemicals) that are designed to help the body fight an intruder. However, consistent release of these chemicals can lead to chronic inflammation, pain, tissue damage, digestive disturbances, skin conditions, and eventually disease.

Symptoms of Food Sensitivity: Food sensitivities are not as quick to occur as food allergies and may take days to cause any visible reaction but when they do appear, can cause trouble in the sinuses, skin and airways, just like allergies. Beyond time, another difference with food allergies is that with food sensitivities, reactions are usually less severe. With food sensitivities, the immune response can be carried by the blood to various parts of the body, leading to any of a hundred symptoms.  This can make it incredibly difficult to identify symptoms of a food sensitivity, and the offending food or foods.

Food Intolerance

This type of reaction does not involve the immune system. Generally a food intolerance is caused by a lack of the ability to properly digest a food, such as seen in lactose intolerance. This occurs when a person lacks the digestive enzyme required to digest lactose (milk sugar).

Symptoms of Food Intolerance: A food intolerance is more isolated, generally causing an acute digestive disturbance (such as abdominal pain or bloating) that subsides after several hours.  Symptoms of a food intolerance are generally quite obvious, assuming there is nothing else going on that could mask the problem.

 How to identify what’s triggering the symptoms

So your child has a mild rash immediately after eating peanuts, or sneezes when there is freshly cut grass. These are likely allergic reactions because they happen all of sudden when exposed to these triggers.

Chronic symptoms like a constant runny nose, poor appetite, frequent headaches, and eczema are highly suspect of being a result of one or several food sensitivities because they don’t come on suddenly and tend to linger.

If a reaction is not immediate or the reaction occurred when many foods were consumed at the same time, how do you know what exactly is causing the reaction? A good place to start is to keep a simple food log. Write down what your child eats and when symptoms occur. Food allergies and food intolerances are generally fast acting reactions, thus a food log may be sufficient to see the pattern. Once a food suspect has been identified as a suspect, simply remove that food from the diet for a minimum of 4 days, then consume a sizable portion of that food on an empty stomach to confirm a reaction.

From this log, in addition to food reactions, if you start to see a seasonal pattern to the symptoms, you may reason that an allergy to a seasonal pollen like grass, ragweed, trees, etc may be an issue as well.

Symptoms like indigestion, bloating, pain, and various other ailments tend to be frequent or chronic, making it difficult pinpoint any single cause. In addition, most individuals react to multiple foods or seasonal and environmental allergens, which becomes confusing, time-consuming, and extremely difficult to figure out. In these cases, a strict elimination diet can be used, however even the strictest of diets may still contain reactive foods. There are certainly some foods which are more common than others for causing adverse reactions, but each person is truly unique. It’s always recommended to work with a physician or nutritionist before eliminating any foods, particularly when it comes to children.

To recap, start with a simple food diary. Then eliminate possible triggers. If this is insufficient, try moving to a more strict elimination diet. If you don’t see results, you’ll may want to consider a food allergy or food sensitivity blood test.

Check out the next post in this two-part series: Adverse Food Reactions: Which Test Is Right For You?

Now that you know the difference between food allergies vs food intolerance vs food sensitivities, what caused your reaction? What can you do to help your body thrive in spite of this?

 Megan Pennington

About the Author: Megan Pennington is a Certified Holistic Health Coach with a Bachelor of Science degree in Dietetics and Human Nutrition. Her specialties include weight management, food reactions, inflammatory conditions, holistic nutrition, fertility issues, and transformational coaching.

She is the founder of MP Holistic Nutrition in Montreal and creator of the Essentials Whole Health Program. She works with clients both locally, internationally, and online to help them achieve the body they desire, a joyful relationship with food, and vibrant health. To connect with Megan, SIGN UP for FREE tips and updates!


  1. Bruno on August 25, 2015 at 3:30 pm

    This article contains very important and great information to know. Food is one of the essentials of the human body needed to keep on living in our daily lives. Simply by knowing that and pinpoint your food allergies and sensitivities, you can considerably improve your health over time. I have done, myself, the food sensivities test and I don’t regret this investment for my own health.

    • Jennifer Roberge on August 28, 2015 at 10:33 am

      Thank you so much for the comment Bruno! I’m very happy to hear that you’ve been able to improve your health by modifying your diet.

  2. John Dolan on July 5, 2018 at 10:19 am

    Such a wonderful blog. Now i have all my doubts clears about allergies. Also taking regular medicine to get relief from it.

  3. Richard L Parez on November 10, 2018 at 12:18 am

    Hi, you share a great article on the topic of Sensitivity of Food Allergy. This is really very embarrassing while I fall down such like the problem.
    Once upon a time, I have attacked with Food allergy. My whole body was covered with the red rush and I felt pain at that time. I felt a little bit fever with a very bad headache. Then I got suggested by a doctor and he told me this is caused by food allergy.
    I’m very much appreciated with your very informative post. Thanks for sharing with us.

  4. […] While there are common food culprits that may worsen your eczema, it’s important to remember that everyone is different and not everyone will experience the same issues with the foods listed below. Understanding your body and knowing which foods work and don’t work for you personally is crucial, keeping in mind that there is a difference between a food allergy and a food-insensitivity.  […]

  5. […] Bien qu’il existe des coupables alimentaires courants qui peuvent aggraver l’ eczéma, il est important de se rappeler que tout le monde est différent et pas tout le monde connaîtra les mêmes problèmes avec les aliments énumérés ci – dessous. Comprendre votre corps et savoir quels aliments travail et ne pas travailler pour vous est personnellement essentiel, en gardant à l’ esprit qu’il ya une différence entre une allergie alimentaire et un manque de sensibilité alimentaire.  […]

  6. […] Si bien no son los culpables más comunes de alimentos que pueden empeorar el eczema, es importante recordar que todos somos diferentes y no todas las personas experimentan los mismos problemas con los alimentos que se enumeran a continuación. La comprensión de su cuerpo y saber qué alimentos trabajo y no hacer el trabajo para usted es crucial, teniendo en cuenta que hay una diferencia entre una alergia a los alimentos y una falta de sensibilidad alimentaria.  […]

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