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Food allergy vs. food intolerance: How to tell the difference

Posted May 17, 2021 by Dr. Julia Thornton

dish of peanuts

Chances are good at one time or another you have experienced unpleasant symptoms — an upset stomach, diarrhea, nausea or bloating — after eating a delicious meal. Reactions from food are common, but it can be challenging to understand the cause.

Food intolerance can trigger some of the same physical symptoms as a food allergy. But, understanding the difference is vital to your health. Eating a food that your body is intolerant to can leave you feeling uncomfortable, but eating a food you’re allergic to can lead to a life-threatening situation.

So, how can you tell what you’re suffering from? The main difference is how your body responds to the food. Summa Health discusses food allergies verse food intolerances to give you insight into what’s causing your trouble. Just remember, your doctor will let you know for sure.

Food allergies

A true food allergy causes an immune response that produces antibodies to attack the unknown invader, usually a protein found in the food you ate. It can affect numerous organs in the body and cause a range of symptoms, from hives and itchiness to vomiting and diarrhea to dizziness or fainting.

In some instances, a serious allergic reaction called anaphylaxis can occur, which is life-threatening. Symptoms can include facial swelling, trouble breathing and a drop in blood pressure. Symptoms of a food allergy usually come on suddenly, while symptoms of food intolerance come on gradually.

The most common food allergies include seafood, peanuts, tree nuts, milk, eggs, wheat and soybeans. If you think you may have a food allergy, it’s important to get an allergy test to know for sure.

The best way to prevent symptoms is to avoid the food altogether and carefully read labels to ensure the product is safe for you to eat. Because mistakes happen, you may need to carry an emergency epinephrine shot (EpiPen) for emergency self-treatment.

Food intolerance

If you’re suffering from food intolerance, the reaction is triggered by the digestive system, rather than an immune response. Food intolerance is the inability to process or break down certain foods and causes mild digestive symptoms, including:

  • Gas and bloating
  • Heartburn
  • Diarrhea
  • Constipation
  • Cramping
  • Nausea
  • Your body may have trouble digesting certain foods due to enzyme deficiencies, or certain food additives or natural chemicals found in foods can irritate your digestive system. The most common food intolerances are lactose, a sugar found in dairy, and gluten, which can be found in wheat, rye, barley, semolina, bulgur and many other grains and processed foods.

    A food intolerance is not life-threatening. In fact, you may be able to eat small amounts of the food without any trouble. In comparison, a food allergy will cause a reaction by eating a microscopic amount, touching or even inhaling the food.

    If you’re suffering from food intolerance, your doctor can help you find ways to prevent a reaction by avoiding or limiting the food with substitutions, such as lactose-free milk. Your provider may even be able to recommend ways to aid digestion of certain foods, such as over-the-counter supplements.

    Celiac disease

    Celiac disease is a common food intolerance of gluten, but it has some features of a food allergy because it involves a response from the immune system. However, people with celiac disease are not at risk for a severe, anaphylactic response.

    The main symptoms of celiac disease are digestive related, but you can experience joint pain and headaches. Continuous ingestion can cause diarrhea, weight loss and malnutrition. Just like other food intolerances, the best treatment is to avoid gluten.

    Though food intolerances are much more common than food allergies, be sure to talk to your doctor to find out what’s causing you trouble and how best to control your symptoms. Reactions from food allergies can range from minor and annoying to life threatening, even if past reactions were mild.

    About the Author

    Dr. Julia Thornton

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