Food Allergy

Definition

A food allergy is an adverse or abnormal reaction to a food or a food additive.

Causes

A few specific foods seem to cause a majority of the food reactions. The most likely triggers of a food reaction include:

  • Peanuts
  • Tree nuts (ie, walnuts, pecans)
  • Eggs
  • Cow's milk and other dairy products
  • Wheat
  • Soy
  • Shellfish and other seafood
  • Tomatoes
  • Fresh fruit, especially citrus, strawberries, melon
  • Food dyes and chemical additives

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

  • Age: young children
  • History of eczema
  • History of other types of allergies, including hay fever

Symptoms

Symptoms include:

  • Gurgling stomach
  • Stomach cramps, pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Skin rash, especially hives
  • Skin itching
  • Cough
  • Wheezing
  • Shortness of breath
  • Swelling in lips, mouth, tongue, throat
  • Nasal congestion
  • Severe drop in blood pressure

Hives

Splotchy body rash -adult

© 2008 Nucleus Medical Art, Inc.

Diagnosis

The doctor will ask about your symptoms and medical history, and perform a physical exam. Food allergies are often diagnosed based on your own observations of reactions to food or drink. It is a good idea to keep a diary of your symptoms, when they occur, and what you have eaten.

Tests may include:

Elimination Diet

You may be asked to go on an "elimination diet." Under your doctor's care, you do not eat a food that is suspected as the cause of your reaction. If your symptoms decrease or go away, your doctor can almost always make a diagnosis. If you eat the food and your symptoms come back, the diagnosis is confirmed. This method should not be used if symptoms are severe.

Scratch Skin Test

Your doctor can also use a scratch skin test. The doctor will put a dilute extract of the food on your forearm or back skin. If there is swelling or redness, an allergic reaction may be present. Using the results of the skin test in combination with your history of symptoms, the doctor will make the diagnosis. This test should not be used if you are severely allergic or have eczema.

RAST or ELISA Test

In these cases, the doctor may order blood tests (RAST or ELISA). These tests measure the level of food-specific IgE in the blood. IgE is a type of protein that the body produces when it comes in contact with something to which it is allergic. The presence of IgE in the blood may indicate an allergy.

Treatment

Avoid foods and food ingredients that cause you to have an allergic reaction. If you think you've eaten something to which you are allergic, and you have difficulty breathing, call for emergency medical help immediately.

Treatments include:

  • Antihistamine medication
  • Epinephrine shot
  • Corticosteroid medication

Prevention

To reduce your chance of having a food allergy reaction:

  • Avoid eating/drinking substances to which you know you are allergic.
  • Read the ingredient label on every food product that you eat.
  • If you go to a restaurant, discuss your allergy with the food server and ask about all ingredients.
  • Learn the chemical names for all your allergens so that you recognize them on an ingredients list.
  • If you have a severe, anaphylactic-type food allergy, ask your doctor if you should carry a dose of epinephrine with you.
  • Consider wearing a medical alert bracelet to inform others of your allergy.

RESOURCES:

American Academy of Allergy, Asthma, and Immunology
http://www.aaaai.org

Food Allergy and Anaphylaxis Network
http://www.foodallergy.org

CANADIAN RESOURCES:

Allergy Asthma Information Association
http://aaia.ca/

Calgary Allergy Network
http://www.calgaryallergy.ca/

References:

Allergy: Principles and Practice . 5th ed. Mosby-Year Book, Inc.; 1999.

Food Allergy and Anaphylaxis Network website. Available at: http://www.foodallergy.org .

Griffith's 5-Minute Clinical Consult . Lippincott, Williams, and Wilkins; 1999.

National Institute of Allergy and Infectious Diseases website. Available at: http://www.niaid.nih.gov .



Last reviewed November 2007 by Kari L. Kassir, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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