The Difference Between Food Allergy and Food Intolerance

Food allergies and food intolerance are influenced by different systems in the body. The immune system is responsible for food allergies, whereas the digestive system affects food intolerance. Regardless of the body's mechanisms in these reactions, food allergies and intolerances can impact a person's diet, health, and quality of life.

This article explores the causes and symptoms of food intolerance and food allergies, how to manage them, and common trigger foods.

Allergenic foods in bowls.


 What Are Food Allergies?

Allergic reactions to food occur when the body recognizes a specific food (an allergen) as a threat and goes into overdrive by producing threat-fighting antibodies called Immunoglobulin E (IgE).

Food allergies affect about 2%-10% of the population, with most food allergies developing in early childhood.

What Is Food Intolerance?

Food intolerance is an adverse reaction to a food that occurs in the digestive system. It can be difficult to determine the difference between food allergies and food intolerance since the symptoms can look and feel very similar.

Food intolerance is far more common than food allergy and affects up to 20% of the population.

The Primary Difference

The biggest difference between food allergy and food intolerance is the body system in charge of the response. The immune system is responsible for the process that causes a food allergy, whereas the digestive system is in charge of the food intolerance response.

How Causes and Symptoms Differ

Food allergies are the result of an immune response to certain foods. When an allergic reaction to food occurs, the immune system is specifically responding to a food protein that the body recognizes as a threat. In the case of allergies, food proteins are the small molecules that make up a particular food.

Food intolerance, on the other hand, is caused by any non-protein component of food. One common example of this is lactose intolerance.

Lactose is the naturally occurring sugar found in cow's milk. People with an intolerance to lactose cannot break down this sugar, which typically results in symptoms such as:

Duration of Symptoms

Food intolerance symptoms are often uncomfortable and can make for a bad day if you eat one of your trigger foods. However, food allergies can have much more severe consequences and for a prolonged period.

A person with food allergies may present with a skin reaction when they are exposed to their trigger foods, including:

Other symptoms of food allergies include gastrointestinal reactions like vomiting or diarrhea.

The most severe allergic reaction to food is called anaphylaxis, which can cause difficulty breathing, loss of consciousness, and even death if not treated immediately with epinephrine.

People with food allergies who are at a higher risk of an anaphylactic reaction include:

  • People who have had an anaphylactic response to a food allergen in the past
  • People with asthma
  • People with allergies to peanuts, tree nuts, and shellfish.

Adolescents are also at a greater risk of food-induced anaphylaxis than adults.

Common Food Allergies and Intolerances

According to the American College of Allergy, Asthma, and Immunology, eight types of foods account for 90% of food allergies.

8 Most Common Food Allergens

The most common food allergies include:

Sesame is the ninth most common allergen, but the ACAAI states that manufacturers will not technically be required to list it as an allergen on food labels until January 1, 2023.

Food intolerances or sensitivities often fall into the same categories as listed above.

One cause of food intolerance that does not trigger food allergies are FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols). Foods that contain high levels of FODMAPs can cause stomach problems for people with an intolerance.

Other common food intolerances include gluten sensitivity and histamine intolerance. Gluten is a protein found in wheat, rye, and barley.

Diagnosis and Management

If you suspect that you or your child may have a food allergy, talk with your healthcare provider. Your provider may refer you to an allergist (a doctor that specializes in treating allergies). They will begin by asking about your health history to determine the food that is causing the allergy.

The next step is diagnostic testing which could be a skin test, a blood test, or both.

Skin Tests

Skin tests are done in a controlled setting under the supervision of an allergist. The most common type of skin test is called a "prick test."

During this test, a tiny drop of the possible allergen is pricked or scratched into the skin. The allergist looks for a reaction and can usually pinpoint the allergen rather quickly.

Blood Test

If you and your provider decide that a blood test is the right option to diagnose your food allergy, you can expect them to take a small sample of your blood.

It typically takes longer to get the results of a blood test since it will need to be analyzed. This analysis looks for IgE, the threat-fighting antibody that is specific to food allergies.

Managing Food Allergies

The most effective strategy for managing food allergies is avoidance of the food allergen.

In some instances, avoidance of food groups is necessary due to the risk of cross-reactivity, which occurs when the body recognizes the chemical makeup of two different foods as a similar threat. For example, someone who is allergic to walnuts may also need to avoid pecans to avoid a possible allergic reaction.

A healthcare provider will prescribe epinephrine, commonly known as an EpiPen, for individuals who are at a high risk for food-induced anaphylaxis.


Allergic reactions to food are an immune response, whereas food intolerance is the result of the digestive system. They can share similar symptoms, like nausea, but food allergies symptoms can be more severe and last longer. A healthcare provider can make an official diagnosis and recommend strategies to manage future reactions.

A Word From Verywell

Food intolerance and allergies can have a significant impact on your daily life. It can be scary to be diagnosed with a food allergy, but remember that not all food allergies are life-threatening. Be open with your friends and family about your or your child's food allergies or intolerances to create a safe space for everyone. If you are concerned about any adverse reactions that you or your child has had to certain foods, talk to your healthcare provider.

Frequently Asked Questions

  • How can you figure out if you have a food intolerance?

    Food intolerance presents as an adverse reaction to food that occurs in the digestive system. If you experience digestive symptoms such as stomachache, bloating, diarrhea, gas, and nausea after eating a certain type of food, you may have a food intolerance. Discuss these concerns with your healthcare provider to learn more.

  • Can you develop food allergies or intolerance later in life?

    Most food allergies occur in childhood, but it is possible to develop allergies to food in adulthood.

  • Do food allergies get worse with time?

    Some food allergies that occur during childhood, such as those to cow's milk and eggs, can be outgrown. However, allergies to peanuts and tree nuts tend to continue into adulthood.

  • How long does it take for food allergens to leave your system?

    Allergic reactions to food typically occur within the first two hours of ingestion and usually resolve within 24 hours.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Teresa Maalouf, MPH
Teresa Maalouf is a public health professional with six years of experience in the field. She has worked in research, tobacco treatment, and infectious disease surveillance. Teresa is focused on presenting evidence-based health information in a way that is clear and approachable.