Food Allergy

What is a Food Allergy?

Referring to an adverse reaction to specific proteins in some foods, a food allergy can produce symptoms ranging from mild (slight intolerance) to severe. Avoidance of known triggers is the only way to treat food allergies, which affect approximately 4 percent of the total population, although emergency treatment may be required for severe, acute reactions.


A food allergy is essentially an over-reaction from the immune system. During a reaction, the body produces an antibody (immunoglobulin E) and a type of white blood cell (mast cell) found in connective tissues accumulates in the affected area. Food allergies are typically triggered by proteins in foods such as nuts, wheat, soy, dairy products, and some types of seafood, including shrimp and shellfish.

What are the Symptoms of a Food Allergy?

Many food allergies aren’t severe, however, some symptoms can be life-threatening. Food allergies occur within a few minutes to an hour.

Symptoms include

  • Abdominal pain
  • Sneezing
  • Vomiting and diarrhea
  • Difficulty breathing
  • Itching around the mouth
  • Hives and rashes
  • Wheezing

Food Allergy Causes

When a person has a food allergy it is because the immune system has reacted to a substance that is generally harmless. This occurs when the immune response is far more sensitive than it should be to those substances. It reacts as if the allergen is a harmful substance, and the resulting reaction can be life-threatening in some people.

Children are more likely to have food allergies than adults. The most common allergens to cause reactions in children are wheat, milk, peanuts, eggs, shellfish, tree nuts, soy and fish. Allergies are often inherited, specifically with a family history of allergies such as atopic dermatitis and asthma. Those who have asthma are more likely to get food allergies and to have more severe reactions to their allergens. Having tobacco smoke in the environment can aggravate allergies too. For some babies, an allergen eaten by the mother can enter the breast milk and cause a reaction in the infant.

How is a Food Allergy Treated?

Patients may be referred to an allergist when a food allergy is suspected. Blood tests and skin tests with a few drops of liquid food extract are usually part of the process of confirming or ruling out a food allergy. A challenge test involving the intake of small amounts of certain foods is sometimes done under a doctor’s supervision.

Treatment includes

Antihistamines or topical steroids are typically prescribed to manage mild reactions. For severe or potentially life-threatening reactions (anaphylaxis), epinephrine (EpiPen, Adrenaclick) is prescribed. It should be used when the first signs of a reaction are observed. Treatment may also include short-acting bronchodilators, steroids, and asthma medications.

Reactions from allergies to food aren’t always immediate and may occur later in the digestion process. Food allergies aren’t the same as food intolerance’s. With food allergies, the trigger food has to be avoided, with intolerances some mild discomfort may be experienced, but total avoidance isn’t always necessary.

Food Allergy Prevention

There is generally no way to prevent food allergies. However, it is believed that breastfeeding a baby for at least four months can make developing a milk allergy less likely. For other allergens, there is currently no way to prevent a child or adult from developing an allergy. What patients can do is to prevent reactions by avoiding the allergen. Creating an environment that is clean and free from mold can help to prevent aggravating a food allergy. The air should be free from smoke and other irritants.

Reading labels can help those with allergies to avoid their allergens. Plan your meals so that you won’t have to eat foods that may have your allergens inside. Talking to an allergist can help you to understand which allergies may be related to each other and what you need to avoid. Many food allergies stem from allergies to trees and other plants. You may need to avoid contact with those related plants to prevent reactions.

Last Reviewed:
September 21, 2016
Last Updated:
December 22, 2017