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Food Allergy Basics

Important Info For Families

Food allergies, which can lead to serious or even life-threatening allergic reactions, develop when the body’s immune system has an abnormal reaction to one or more proteins in a food.

In general, the incidence of food allergy has increased over the past decade. Peanut allergy, tree nut allergy, or both, are reported by more than one percent of the US population, with an increase in children over that time frame. The most allergy-prone foods are cow’s milk, egg, peanuts, soy, wheat, tree nuts, fish, and shellfish.

In people with classic food allergies, symptoms typically occur quickly, within minutes to two hours after eating. The most common symptoms include itchy mouth, hives, nasal congestion, wheezing, trouble breathing, throat constriction, vomiting, or loss of consciousness. One myth that needs debunking is that an individual’s allergic reactions present with the same symptoms, or look the same, each time. This is not true. Studies published in both the United States and United Kingdom have shown that up to a third of severe allergic reactions have occurred in individuals that have a history of only hives on previous reactions. This is especially important for parents to note.

A complete and detailed medical history is essential for initiating the proper work-up for any food allergy. Specific skin and blood testing gives providers added information on determining the likelihood of classic food allergy. The gold standard test for all food allergy is the oral food challenge, where the food is ingested by the patient in a controlled setting (clinic or hospital in most cases) to monitor for reaction. It is important to note that neither the size of the reaction site during the skin test nor the results on blood tests translate into severity of allergy. These tests only speak to the likelihood of any reaction.

The highest risk for any food-induced reaction stems from direct ingestion of the food. Severe reactions from contact or inhalation exposure to the allergen seem to be extremely rare. Contact with the allergen may lead to localized hives, but will not result in a full body reaction. Wiping down the skin area of allergen contact often resolves the reaction.

Once a food allergy is confirmed, the best treatment is to avoid the food. Patients must carefully check ingredient labels for all food products. The most important aspect of the treatment plan is to have emergency medications available at all times in case of a severe allergic reaction. Timely administration of self-injectable adrenaline reverses the symptoms of anaphylaxis, calming the severe reaction until the patient can get to the emergency room for further treatment.

Most childhood food allergies are resolved during childhood or adolescence. The rate at which the allergy is outgrown depends on the food. Cow’s milk allergy affects approximately 2.5 percent of children under two years of age. It is usually outgrown by adulthood. Egg allergy affects 1 to 2 percent of children. The majority of cases resolve by adulthood. Peanut and tree nut allergies affect about 1 to 2 percent of children. It is likely to be a lifelong disorder for most patients, although 20 to 25 percent outgrow peanut, and at least 9 percent outgrow tree nut allergies.

If you suspect food allergy in you or your loved ones, please speak to your physician. A referral to an allergist may be warranted.

Ananth Thyagarajan
Ananth Thyagarajan, MD, or Dr. T as he is known by many of his patients, is an allergist-immunologist and father of two. He specializes in allergy, asthma, and food allergy and sees patients at Allergy Partners of Richmond.
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