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by EBSCO Medical Review Board

Food Allergy

Definition

A food allergy is an abnormal response to a food or a food additive.

Causes

A food allergy is when the body mistakes a food as being harmful. This makes the immune system release chemicals into the blood that cause symptoms to happen. The most common triggers of a food reaction are:
  • Cow's milk
  • Eggs
  • Peanuts
  • Wheat
  • Soy
  • Fish
  • Shellfish
  • Tree nuts such as walnuts and pecans
  • Sesame seeds

Risk Factors

A food allergy often starts when a person is a child. It may also start or continue when a person is an adult. Things that may put you at risk are:
  • Other allergies, such as eczema or hay fever
  • Family history of food allergies

Symptoms

Symptoms may be:
  • An itchy skin rash
  • Swelling of the lips, mouth, or throat
  • Coughing or wheezing
  • Shortness of breath
  • Belly cramps
  • Diarrhea
  • Vomiting
Hives
Splotchy body rash -adult
© Nucleus Medical Media, Inc.

Diagnosis

You will be asked about your symptoms and past health. A physical exam will be done. The allergy can be confirmed with a:
  • Skin prick test to look for a skin reaction when exposed to a food
  • Blood test to look for an antibody that is present when you are exposed to a food
  • An oral food challenge to watch for a reaction to a food that you eat with a healthcare provider present
You may need to see a doctor who treats allergies.

Treatment

Some people may need medical care right away. Medicine will be given to help quickly open airways.
A food allergy can be managed. Options are:

Avoid the Food

The best way to manage this allergy is to avoid the allergen. Other foods that may have been around the allergen can also cause problems. Education about the allergen and food labels can be helpful.

Medication

Medicine can help to manage minor symptoms like itching. Avoidance is the most important step. Medicine should only be used if an allergen was eaten by accident. Minor symptoms can be managed with:
  • Antihistamines to decrease swelling and itching
  • Corticosteroids to treat severe swelling and itching
An epi pen is needed for those who have had severe reactions. It will deliver the medicine epinephrine. It can quickly open airways and ease swelling. It needs to be nearby at all times.

Prevention

There is no known way to prevent food allergies. Parents should talk to their child's doctor about when to start foods that are highly allergenic, such as peanuts.

RESOURCES

American Academy of Allergy, Asthma & Immunology
http://www.aaaai.org
Food Allergy Research & Education
https://www.foodallergy.org

CANADIAN RESOURCES

Allergy Asthma Information Association
http://aaia.ca
Calgary Allergy Network
http://www.calgaryallergy.ca

References

Bird JA, Lack G, Perry TT. Clinical management of food allergy. J Allergy Clin Immunol Pract. 2015 Jan-Feb;3(1):1-11.
Food allergy. National Institute of Allergy and Infectious Diseases website. Available at: https://www.niaid.nih.gov/diseases-conditions/food-allergy. Accessed September 18, 2020.
Immunoglobulin E (IgE)-mediated food allergy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/immunoglobulin-e-ige-mediated-food-allergy. Accessed September 18, 2020.
3/17/2015 DynaMed Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T114561/Immunoglobulin-E-IgE-mediated-food-allergy: Du Toit G, Roberts G, et al. Randomized trial of peanut consumption in infants at risk for peanut allergy. N Engl J Med. Feb 26;372(9):803-813.

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