5 Answers About Food Allergies

What causes food allergies, how food allergies are treated, and three conditions related to food allergies in children.

Eight small serving bowls containing eight common food allergens—shellfish, soy, milk, peanuts, nuts, eggs, sesame seeds, and fish.

Updated on March 11, 2024

A food allergy is an allergic reaction to consuming certain foods or coming into close contact with certain foods.

Like other allergic reactions, food allergies are a response by the immune system. The immune system is a network of cells, tissues, and organs that work together to defend the body against harmful substances. Viruses, bacteria, infectious fungi, and chemical pollutants are some of the things that the immune system protects against.

When a person has an allergy, the immune system responds to a typically harmless substance as if it were harmful. When a person has a food allergy, the immune system reacts to proteins in a specific food (or foods) as if they were something that could cause the body harm.

The immune reaction that occurs with a food allergy can affect the skin, the respiratory system, and the gastrointestinal tract. Symptoms can range from mild discomfort to anaphylaxis—a severe, life-threatening allergic reaction that causes the body to go into shock.

Food allergies affect both children and adults, and food allergies can develop at any age. However, food allergies most often begin in early childhood.

What foods can a person be allergic to?

Wheat, shellfish, eggs, milk, peanuts, nuts, and soy account for most food allergies. However, these are not the only foods that a person can be allergic to—a person can be allergic to any food. A person can also be allergic to multiple foods and non-food substances.

What causes food allergies?

The causes of food allergies are not fully understood, and it is not known why some people develop food allergies and other people do not. It is also not known why some people have severe reactions to food allergies, and others have less severe allergic reactions.

Research suggests that food allergies occur as a result of genetics and environmental factors that a person is exposed to. Having parents or family members with food allergies puts a person at risk for having food allergies, but this does not guarantee a person will have food allergies.

What conditions are related to food allergies?

Food allergies also overlap with other allergic conditions, including atopic dermatitis, allergic rhinitis, and asthma.

  • Atopic dermatitis is the most common form of eczema, an inflammatory skin condition that causes itching, dry skin, and a weakened skin barrier.
  • Asthma is an inflammatory respiratory condition that causes a narrowing of the airways in the lungs and makes it difficult to breathe.
  • Allergic rhinitis is an allergic reaction that causes symptoms like runny nose, watery eyes, sneezing, and itchy nose/throat. One example is hay fever, where a person is allergic to pollen.

The progression of atopic dermatitis, food allergies, allergic rhinitis, and asthma are sometimes referred to as the atopic march, allergic march, or atopic triad. For people with these co-existing conditions, exposure to allergens can trigger symptoms.

Can a child outgrow food allergies?

Many children outgrow their food allergies and are eventually able to tolerate the foods they are allergic to. This is more common with allergies to soy, eggs, milk, and wheat. Allergies that involve nuts and shellfish are more likely to persist for much longer periods of time and may be lifelong.

A healthcare provider—typically an allergist—can order testing to determine if a person has outgrown a food allergy. Because allergic reactions can occur during testing, testing must always be performed in a controlled healthcare setting.

How are food allergies treated?

Identifying, eliminating, and avoiding all foods and substances that cause an allergic reaction is the main focus of treatment. People with food allergies and parents of children with food allergies will need in-depth patient education on foods and behaviors to avoid. In other words, they will need to work closely with a healthcare provider.

Preparing for emergencies is another important part of a treatment plan. This includes having an emergency plan and carrying self-injection epinephrine syringes—pre-filled syringes that contain a drug used to counteract anaphylaxis.

A healthcare provider may discuss other treatment options, including immunotherapy, drugs that ease symptoms, and drugs that help block or reduce the severity of allergic reactions.

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