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Food Allergies

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Updated January 29, 2013

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Peanuts often seem to cause some of the most serious food allergy reactions.

Peanuts aren't the most common food allergy triggers, but they do seem to cause some of the most serious reactions.

Photo by Peter Finnie

Food allergies are perhaps one of the best-known, but also misunderstood, conditions that affect children.

From people who don’t think food allergies are that dangerous to people who don't think food allergies are that common, we all still have a lot of work to do about food allergy education.

Food Allergies by the Numbers

Food allergies are common.

It is thought that 5% of children under the age of 5 have food allergies. That number drops to 4% for older teens and adults, but overall, it seems like the prevalence of food allergies has been increasing for 10 to 20 years.

The eight most common types of foods or food allergens that trigger 90% of allergic reactions are eggs, milk, peanuts, tree nuts (like almonds, walnuts, pecans), soy, wheat, crustacean shellfish (like crab, lobster, shrimp), and fish (like bass, flounder, cod), even though it is reported that at least 160 foods can trigger allergic reactions.

Children with food allergies are 2 to 4 times more likely to also have asthma, eczema, and allergic rhinitis (hay fever).

More importantly, it is estimated that severe allergic reactions to foods lead to 30,000 emergency room visits, 2,000 hospitalizations, and 150 deaths each year.

Symptoms of Food Allergies

Immediate signs and symptoms of food allergies, which occur within a few minutes to a few hours of ingesting something to which you are allergic, can include:

  • hives
  • oral itching or a tingling sensation in the mouth
  • swelling of the lips or a swollen tongue
  • cough, wheezing, or chest tightness (trouble breathing)
  • nausea, vomiting, or diarrhea
  • cramping abdominal pain
  • low blood pressure (hypotension)
  • dizziness or fainting
  • excessive tearing
  • swelling around the eyes (periorbital edema)

Anaphylaxis symptoms -- which include multiple allergy symptoms, especially trouble breathing and/or reduced blood pressure -- are life-threatening and require immediate medical attention.

Symptoms that are more delayed, occurring hours to days later, may include a rash, cough, abdominal pain, diarrhea, or irritability with food refusal. These delayed food-induced allergy symptoms are likely not caused by the same IgE-mediated mechanisms as immediate symptoms are, though.

Diagnosis of Food Allergies

Since many non-allergic conditions, such as lactose intolerance, celiac disease, or irritable bowel syndrome, can also cause symptoms after you eat certain foods, it is important to get an accurate diagnosis if you think that your child has food allergies.

In addition to not restricting your child's diet unnecessarily if he doesn't have a true food allergy, an accurate diagnosis of food allergies will help to make sure that he avoids the foods to which he really is allergic.

Of course, allergy testing is the best way to help figure out what foods are causing your child's food allergies. This can include skin prick testing or allergen-specific serum IgE allergy blood tests, although both can lead to an over-diagnosis of food allergies, identifying some foods to which your child may not actually be allergic.

Which allergy test should you do? Skin prick testing is probably more accurate, but the allergy blood tests are more widely available -- your pediatrician can order this test at your local lab, which makes them popular.

The gold standard for diagnosing food allergies is the oral food challenge, in which the child is given the food that you think he is allergic to, under close observation, to see if he will have a reaction. It is that threat of a reaction that makes some parents hesitant to want to use this as a method to diagnose their child's food allergies.

Other allergy tests, including intradermal testing and patch testing, are not recommended ways to diagnose food allergies.

Management of Food Allergies

Unfortunately, food allergies are usually managed, not treated.

The mainstay of that management is:

  • filing an allergy management plan at school
  • strict avoidance of any foods to which your child is allergic
  • learning to always read food labels, even if you have previously given the food to your child, and avoid foods with labels that are hard to interpret or that say they "may contain [allergen]" or are "produced in a facility that also uses [allergen]," if your child is allergic to that specific allergen
  • redo allergy testing about every year for milk, egg, soy, and wheat allergies, and every 2 to 3 years for peanuts, tree nuts, fish, and crustacean shellfish, which kids are less likely to outgrow
  • get the child a medical identification bracelet to help identify that he has food allergies (older kids might get an anaphylaxis wallet card)
  • have two doses of an epinephrine auto-injector available at all times (home, school, camp, etc.), such as the EpiPen, EpiPen Jr., Twinject 0.30mg or Twinject 0.15mg auto-injectors

It is also important to work with your child's school or daycare to make sure they know about your child's food allergies, can recognize symptoms of an allergic reaction, can implement your child's allergy management plan, and have a plan to eliminate the foods that trigger the child's allergies from his meals and classroom.

What You Need To Know

Other helpful things to know about food allergies include that:

  • Food allergies usually don't cause just a runny nose or congestion.

  • Some extensively baked, heat-denatured foods, like milk and eggs, may not trigger an allergy, especially if eaten in small amounts.

  • Many studies have shown that 50 to 90% of presumed food allergies aren't really allergies, which makes getting an accurate diagnosis important.

  • Get nutritional counseling and be sure that your pediatrician is monitoring your child's growth, especially if he has multiple food allergies, as that can put your child at risk for missing out on important nutrients, like calcium (for those with milk allergies).

  • Regularly check the expiration dates on your epinephrine auto-injectors so that you can replace them in time. Also be sure that any new epinephrine injector that you get from the pharmacy isn't set to quickly expire. Ideally, it will be good for at least 6 to 12 months before expiring (the longer the better).

  • Surprisingly to many parents, children with soy allergies can usually safely eat soybean oil and those with peanut allergies can eat peanut oils. You still have to avoid cold-pressed, expelled, or extruded oils, though.

  • Allergens can be hidden ingredients in many foods, so while it is easy to avoid drinking milk if your child is allergic to milk, it can be harder to know to also avoid the many non-dairy products that contain the milk derivative casein.

  • Allergen-specific immunotherapy is not currently recommended to treat food allergies.

A pediatric allergist can be an important part of your child's allergy management team, to help diagnose your child's allergy, help you avoid all of the foods to which he is allergic, and perhaps help you get to the day where you can try an oral food challenge to see if he has outgrown his food allergy.

Sources:

The Food Allergy & Anaphylaxis Network. School Guidelines for Managing Students with Food Allergies. http://www.foodallergy.org/page/food-allergy--anaphylaxis-network-guidelines. Accessed April 2012.

National Institute of Allergy and Infectious Diseases. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Report of the NIAID-sponsored Expert Panel. October 2010.

U.S. Food and Drug Administration. Food Allergies: What You Need To Know. http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm079311.htm. Accessed April 2012.

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