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What is a Food Allergy?

​Food allergy occurs when the immune system attacks a food protein. Ingestion of the food triggers sudden release of chemicals including histamine, resulting in symptoms of an allergic reaction. The symptoms may be mild (mild rash, hives, itching, swelling) or severe (trouble breathing, wheezing, loss of consciousness, etc.). A food allergy reaction can be fatal. Scientists estimate that approximately 12 million Americans are allergic to at least one food. 
     What is the difference between food allergy and food intolerance? Many people think the terms food allergy and food intolerance mean the same thing; however, they do not.  Food Intolerance usually refers to a condition that is not immediately life-threatening. Common examples are lactose intolerance and gluten intolerance.  Lactose intolerance means that lactose is not digested properly due to a lack of the enzyme needed for the proper breakdown of this milk sugar. Gluten intolerance refers to digestive and other problems with gluten, a storage protein found in wheat, barley, and rye. The term “gluten intolerant” is used loosely to refer to people who have the diagnosis of Celiac Disease (an autoimmune disease) and others with less specific negative health responses to gluten. 
     A Food Allergy occurs when the immune system mounts an immediate severe reaction to a certain food protein. This kind of reaction happens when the body creates immunoglobulin E (IgE) antibodies to a food. When these IgE antibodies interact with the food protein, histamine and other chemicals (called “mediators”) are released, causing hives, asthma, or other symptoms of an allergic reaction.  This kind of reaction can be very severe and life-threatening.

What foods can cause an allergic reaction?

 Any food can cause an allergic reaction, though 90% of people with food allergies are allergic to at least one of the following foods: cow’s milk, egg, peanuts, tree nuts (e.g. pecans, walnuts, cashews, pistachios, pine nuts, brazil nuts), fish, shellfish (e.g. shrimp, lobster, crab), wheat, soy.

Image by Juan José Valencia Antía
Image by Kelly Sikkema

What are the symptoms of an allergic reaction?

  Symptoms can range from mild to life-threatening. Each time a person experiences a reaction, the symptoms can vary. Symptoms typically appear within minutes to two hours after eating the food allergen. Symptoms may include one or more of the following: hives, rash, itching, swelling or puffiness of skin, nausea, vomiting, abdominal cramps, diarrhea, excessive severe runny nose and sneezing, difficulty breathing, wheezing, low blood pressure, loss of consciousness. 


What is anaphylaxis?

​The definition of “anaphylaxis” is very broad to allow for a range of symptom types and severities. The most recently accepted medical definition says:
“Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death.”
Ask AH for source of definition.


Image by Nathan Dumlao

How do children describe a reaction?

Children use words and ideas they understand so their descriptions might be different from how an adult would describe allergic symptoms.  A child might say:

  • "This food's too spicy." 

  • “My tongue is hot [or burning]." 

  • "It feels like something’s poking my tongue."

  • "My tongue [or mouth] is tingling [or burning]."

  • "My tongue [or mouth] itches."

  • "It [my tongue] feels like there is hair on it."

  • "My mouth feels funny."

  • "There's a frog in my throat."

  • “Something is stuck in my throat."

  • "My tongue feels full [or heavy]."

  • "My lips feel tight."

  • "It feels like there are bugs in there." (to describe itchy ears)

  • "It [my throat] feels thick.”

  • “It feels like a bump is on the back of my tongue (throat)

If you suspect that your child is having an allergic reaction, seek medical help immediately. Follow your doctor’s instructions.


What is the treatment for allergic reaction?

For severe allergic reactions, the first treatment is injectable epinephrine (also called adrenaline) such as the EpiPen® or Auvi-Q™. These are available by prescription and must be within easy reach at all times.  (Your doctor may also prescribe antihistamines and an inhaler.)

Is there a cure for food allergies?

​Until recent years, food allergies have been managed by strictly avoiding the food protein that causes allergic reaction.  This means careful food selection, ingredient label reading and concern about “cross contact” with allergens during food processing and preparation.  Currently there are treatments including "oral immune therapy" (OIT) and and FDA approved peanut allergy treatment that can be appropriate for some people with allergies.  Check out the Medical News section of our homepage for more on food allergy research and treatment.

What is "cross-contact"?

Cross contact (sometimes called - cross contamination) is when mixing or “contact” with an allergen occurs during food preparation, cooking, storage or serving.  

How does "cross-contact" happen?

  • Some food manufacturers process foods on shared lines and may not clean them fully when changing to the next food item. 

  • Restaurants may use shared utensils, cookware, or cutting boards.

Additional Resources

How can I avoid "cross-contact" with food allergens?

  • Wash hands or change gloves when handling food for someone who has a food allergy.

  • Make sure all tools and surfaces are cleaned thoroughly before food prep begins.

  • Read ingredient labels carefully. 

  • Call the food manufacturer to asked questions about shared production lines, etc. 

  • If a label says something like “processed in a facility that contains allergens” learn more details from the manufacturer and/or discuss with your allergist before trying the product. 

  • Create a labeling system at home to identify which foods are safe.

  • Keep all foods sealed to avoid allergens splashing/leaking onto your child’s food.

  • Avoid buffets. Accidents can happen due to unintentional sharing of serving utensils or unnoticed spills from one container to another.

  • Teach your child safety tips: don’t share foods, cups or utensils; wash hands before eating or after contact with food allergens.

  • Wipe down shopping carts, chairs, tables, groceries, etc.

  • Beware of lotions, soaps, bath products, toothpaste, medications, cosmetics, etc. (i.e. tree nut oil or wheat can be a common ingredient in body lotions).

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