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Food Allergy Versus Food Intolerance

Reviewed by: HU Medical Review Board | Last reviewed: March 2022

You may have a food allergy or food intolerance if you develop unwanted symptoms after eating a food. It can be hard to tell the difference between these 2 conditions. However, these are 2 different responses that involve different body systems. It is important to understand the difference between them.1

Food allergies and intolerances concern many. Plus, the number of people affected by these conditions is rising. Food allergies affect 32 million people in the United States, and even more people have food intolerances.1

Knowing more about food allergies and intolerances can help you find out which one affects you. With the right diagnosis, you can pursue treatment that relieves your symptoms. You can also take action to prevent unpleasant effects triggered by certain foods.

What is a food allergy?

A food allergy is a reaction to something you eat. This reaction is a response by the immune system. The body decides that certain proteins in food are dangerous even though they are harmless in other people. To protect you, the immune system reacts by releasing mast cells. This results in symptoms that can be minor to severe.1-4

A few things set food allergies apart from food intolerances. Food allergies can lead to serious symptoms like anaphylaxis, while intolerances do not. Symptoms can occur within minutes or in the first few hours after eating. Even a tiny bit of the offending food can spark an allergic response.1-4

What is a food intolerance?

A food intolerance is a response from the digestive system rather than the immune system. The body cannot break down some or all of the compounds in the food.2-4

Although troubling, food intolerances pose less threat than food allergies. They do not cause anaphylaxis. The reactions can be uncomfortable, but they are not life-threatening. How bad the response gets often depends on how much of the food you eat. Symptoms may not appear right away and may even show up the next day.2-4

What causes food allergies and intolerances?

A number of things can cause food allergies and intolerances. The cause varies from person to person.

An immune system reaction causes food allergies. Allergies can develop after eating the same foods often. These foods trigger the most allergic responses:1,2,4,5

  • Eggs
  • Fish
  • Milk
  • Peanuts
  • Sesame
  • Shellfish
  • Soy
  • Tree nuts
  • Wheat

A lack of enzymes needed to digest food can cause food intolerances. Food intolerances can also be tied to acid reflux, asthma, Celiac disease, chronic fatigue syndrome, irritable bowel syndrome, and other illnesses or infections of the digestive system. The following foods often cause the most trouble with intolerance:2-4

  • Carbohydrates
  • Chocolate
  • Citrus
  • Eggs
  • Food additives
  • Fructose in fruit
  • Lactose in dairy
  • Sulfites

Certain things can increase your chance of developing food allergies and intolerances. These include ethnicity, genetics, and regular contact with certain allergens. People with allergic diseases in their family, Black people, and food workers have a higher risk of food allergies.4

What are the symptoms of food allergies and intolerances?

Food allergies and intolerances share symptoms like diarrhea and stomach cramps.2,4

However, trouble breathing, burning or itching skin, rashes, and swelling of the tongue or throat are more common with food allergies.2,4

Symptoms of food intolerances include:2,4

  • Bloating, gas
  • Diarrhea, stomach cramps
  • Headaches, including migraines
  • Heart palpitations
  • Nervousness
  • Sweating
  • Tightness in the chest and face
  • Tremors

These symptoms can also occur with food allergies:2,4

  • Anaphylaxis
  • Fainting
  • Feeling dizzy
  • Hives or rash
  • Low blood pressure
  • Nausea
  • Runny nose
  • Swelling of the eyes, face, lips, mouth, throat, or tongue
  • Vomiting

Among these symptoms, anaphylaxis is the most critical. It can lead to choking, shock, and even death in just a short time. More than 40 percent of children and 50 percent of adults with food allergies have had anaphylaxis.1

How is a food allergy or intolerance diagnosed and treated?

A doctor can diagnose a food allergy or intolerance. They will first review your history of symptoms. Your doctor may ask you to keep a food journal and remove presumed trigger foods from your diet for a short time. They can confirm the diagnosis with a blood or skin prick test.2,4

Although some food allergies and intolerances resolve on their own, no cure exists for those that remain. You can take measures to address and prevent symptoms. Some of the actions are unique to the type of response.1,4

First, you can choose to not consume foods that trigger an immune or chemical response. To help you choose wisely, read the labels on foods you buy. Ask what is in the meals other people prepare.

If you have a food allergy, your doctor can prescribe epinephrine, commonly known as an EpiPen®. This is a shot if you become exposed to your allergen and develop anaphylaxis, a severe life-threatening reaction. If you do use epinephrine, call 9-1-1 right away for emergency medical care.1-4

In 2020, the U.S. Food and Drug Administration (FDA) approved Palforzia® [Peanut (Arachis hypogaea) Allergen Powder-dnfp], a type of oral immunotherapy, to treat some peanut allergies.6

If you have a food intolerance, you may be able to eat a small amount of the trigger food. Know your limits and stick with them. Taking enzymes and reducing stress may also lessen symptoms and allow you to eat certain foods. Talk to your doctor about what is right for you.3

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