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How to Tell if You Have a Food Allergy, Sensitivity or Intolerance

It can be hard to determine if you have an actual allergy or an intolerance to something you eat. Here's how to know.

Taylor Leamey Senior Writer
Taylor Leamey writes about all things wellness, specializing in mental health, sleep and nutrition coverage. She has invested hundreds of hours into studying and researching sleep and holds a Certified Sleep Science Coach certification from the Spencer Institute. Not to mention the years she spent studying mental health fundamentals while earning her bachelor's degrees in both Psychology and Sociology. She is also a Certified Stress Management Coach.
Expertise Sleep, Mental Health, Nutrition and Supplements Credentials
  • Certified Sleep Science Coach, Certified Stress Management Coach
Taylor Leamey
5 min read
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Despite our need for nutrients, foods can trigger negative responses from the body, with varying degrees of severity. These responses can be broken down into three categories: allergy, sensitivity and intolerance. 

Because the symptoms often overlap, there's quite a bit of confusion about the differences between them and what they mean for your body. Moreover, the clinical definitions are based on internal responses. Below we'll explore the key distinctions between food allergies, sensitivities and intolerances. 

Food allergy

Food allergies are serious and can be potentially life-threatening. An estimated 32 million Americans have a food allergy. They typically develop in childhood, though they can pop up later in life. The key distinction that separates food allergies from other reactions is that your immune system is activated when it mistakes the food for something harmful. 

There are two typical types of allergic reactions caused by the immune system. The most common antibody is immunoglobulin E (IgE), which causes an immediate reaction as it attempts to neutralize the food. Think anaphylaxis or hives

A non-immunoglobulin E (non-IGE) reaction is less understood. It happens due to other immune components that don't include IgE antibodies. This reaction is delayed because the food must get to the digestive tract to trigger symptoms. It's typically not considered not life-threatening. 

Some studies have suggested that there is a genetic component to food allergies. A child is more likely to develop allergies if both parents have them. The most common food allergies are peanuts, shellfish, milk, eggs, fish, wheat and soybeans. 

Common symptoms of a food allergy:

  • Hives 
  • Feeling dizzy or lightheaded
  • Tingling or itching
  • Swelling of the face, mouth or throat
  • Difficulty swallowing 
  • Anaphylaxis
Woman holding her stomach in discomfort after drinking milk
AntonioGuillem/Getty Images

Food intolerance

Food intolerances mean your body can't fully digest a certain type of food, but your immune system is not involved. This type of response can be extremely uncomfortable and cause physical symptoms like stomach pain or diarrhea. The most common type of food intolerance is lactose intolerance, followed by gluten intolerance.

Food intolerance can be the result of many causes in your digestive system. It might be that you lack an enzyme in the body that allows the gut to digest the food, like in the case of lactose intolerance. Another reason could be a sensitivity to chemicals or additives within the food. However, adverse reactions to additives in food are rare

With food intolerances, you have more control over the reaction. Sometimes a small amount of the food can pass and won't upset your digestive system. Or, you can prevent the reaction, like in the case of a lactose-intolerant person taking Lactaid before consuming dairy products. There is no way to prevent a food allergy other than fully restricting that food from your diet.

Food intolerance can worsen with age. For example, as we age, our bodies are less capable of handling dairy because our intestines make less lactase, the enzyme needed to break down lactose. 

Common symptoms of food intolerances include but are not limited to:

  • Gas
  • Cramping
  • Bloating
  • Constipation
  • Diarrhea
  • Stomach pain
  • Headaches

Food sensitivity

Food sensitivities are more tricky. Food sensitivities and intolerances are often incorrectly used interchangeably, but they're not the same thing. Unlike food intolerance, there is a slow response that is not life-threatening. Symptoms aren't immediate and can take days to appear. That's why people can go a lifetime without realizing they have a particular food sensitivity.

More research is needed to fully understand the scope of food sensitivities. We know that food sensitivity is not a food allergy because the source of the reaction comes from an imbalance of good and bad bacteria in the gastrointestinal tract. 

Common symptoms of food sensitivities include but are not limited to:

  • Fatigue
  • Joint or muscle pain
  • Migraines
  • Brain fog
  • Itching 
Doctor performing a patch allergy test on a woman's back
Science Photo Library

How to identify if you have a food allergy, intolerance or sensitivity

If you're having regular reactions to food, it's important to visit your doctor. They'll be able to help you determine which reaction you have and make a plan to manage your symptoms. Allergy tests will determine if you have a food allergy. 

It's harder to nail down a food intolerance or sensitivity. The only proven test for food intolerance is a hydrogen breath test, which diagnoses lactose intolerance. 

There are additional things you can do to identify food sensitivities and intolerances. First, you can work with your doctor to build a food elimination plan that removes certain foods from your diet for around a month and slowly reintroduces one food at a time to gauge if a reaction occurs. When a reaction occurs, you'll then be able to track it back to a particular food.

You can also keep a food diary that details the foods you eat, how you feel and any reactions. By keeping track of all these factors, you'll be able to notice patterns in the foods you eat and the reactions you have. 

Tips for managing food reactions

If you have food allergies, sensitivities and intolerances, it can make planning your diet more complicated, but not impossible. Even with dietary restrictions, you can still enjoy food and have a well-rounded diet. 

  • Tailor your diet: Even the reactions that aren't serious are uncomfortable. To avoid this, work with your doctor or dietician to eliminate your trigger foods and adapt your diet to ensure you get enough nutrients.  
  • Pay attention to food labels: When grocery shopping and cooking for yourself, it's important to carefully read nutritional labels to ensure the products are truly free of your allergies. According to the FDA, food allergens must be declared on labels
  • Listen to your body: If you live with an intolerance or sensitivity, you aren't required to restrict your diet as severely as you would with an allergy. You may accidentally intake triggering foods at restaurants or family dinners without realizing it. It's important to listen to what your body is telling you so you can address it accordingly. 
  • Keep an epinephrine shot: Depending on the severity of your allergy, you may need to carry an epinephrine shot like an EpiPen® with you. This is reserved for food allergies and not required for ood sensitivities and intolerance.

Too long; didn't read?

Food allergies, sensitivities and intolerances are three unique responses our bodies have to food. Allergies are the most severe and can be fatal. Sensitivities and intolerances are less severe but can be extremely uncomfortable, depending on the symptoms. All of them require adaptation of your diet. 

You can manage these reactions with a careful lifestyle. Make sure you closely read nutritional labels and take note of your symptoms to identify reactions. And always remember to consult your doctor if things change. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.