September 30, 2026 | Black & Kletz Allergy
Thousands of children and adults experience untoward reactions after eating certain foods in the U.S. every year. The reactions can vary in severity from mild itching and rashes to life- threatening anaphylactic reactions. Many children and adults require urgent evaluation and treatment in emergency departments due to allergic reactions to foods. Most of these reactions and emergency room visits can be prevented by early diagnosis and interventions for food allergies.
A reaction occurs when the immune system mistakenly considers a food as potentially dangerous and as a result mounts a defensive attack on it. Though the exact reason for this “mistake” is not clearly understood, genetic factors are believed to play a major role.
When an inpidual experiences a reaction after exposure to a food, it is very important to identify the specific food that triggered the reaction in order to prevent similar or more severe reactions in the future.
The first and the most important step in the diagnostic process is obtaining a comprehensive history and physical examination. Accurate information about the specific food the person has eaten, including the list of ingredients if it is a packaged food, is extremely helpful. The duration between the exposure and the onset of symptoms, the specific symptoms, the progression of the reaction over the next minutes and hours, and the response to any treatment given helps in establishing the diagnosis.
The next step in the diagnostic process typically involves a test to detect specific IgE antibodies to the food in the patient. If the inpidual has consumed multiple foods at the same time before the onset of symptoms, the tests include identification of the specific IgE antibodies to all the suspected foods.
There are 2 ways of testing for food-specific IgE antibodies and they are complementary to each other. One way is perform prick testing on the skin where a small quantity of a food antigen (i.e., protein that triggers the reaction) is introduced into the superficial layers of the skin and observed for a response after 20 minutes. An itchy swelling at the site of the prick test surrounded by redness confirms that the inpidual has specific IgE antibodies to the food that was tested. Another method used to test for food-specific IgE antibodies, is to obtain a small blood sample from the person and having a clinical laboratory measure the amount of specific IgE antibodies to the foods in the blood sample.
Identification of the specific IgE antibody to the food in the context of a history of reaction usually confirms an allergy to the food and indicates a heightened risk for a similar or more severe reaction if the inpidual consumes the same food in the future. Avoidance of the specific food or foods mitigates the risk of subsequent reactions.
Many people ask if there is a test to identify all the foods a person is allergic to even if the inpidual has never eaten the food before or never had a reaction from these foods before. These tests are sometimes referred to as food “panel” tests.
Skin tests or blood tests to detect an allergy to a food the inpidual has never had a reaction to are not recommended. They may do more harm than good. A positive antibody detection in the absence of a history of a reaction only identifies sensitization to that food, not an allergy. It will not identify the likelihood of an adverse reaction on exposure. Thus, a positive test in that context is more likely to be a false positive test rather than truly positive. This could lead to telling the inpidual to avoid a certain food unnecessarily. In addition, this can also result in the psychological impact of a food allergy diagnosis which would have nutritional implications, social barriers, potential unnecessary treatments, and increased healthcare costs.
The “gold standard” test used in the diagnosis of food allergies is an oral food challenge. This procedure involves feeding the inpidual with the suspected food, beginning with a very small amount and gradually increasing the amount every 20 minutes while closely monitoring for adverse effects. This process has a risk of a severe allergic reaction and thus should be administered by allergists trained in the early identification of an allergic reaction. The allergist should be prepared to treat an allergic reaction if it occurs during the oral food challenge.
If an inpidual has a reaction at any stage of the oral food challenge, it confirms an allergy to that food. It may also provide an estimate of a possible threshold dose needed to invoke an allergic reaction. If the inpidual tolerates the target dose of the food without any reaction, the food can generally be incorporated in their regular diet.
It should be noted that all patients who have food allergies should carry a self-injectable epinephrine device or an epinephrine-containing nasal spray at al times. They should know how and when to use them and instructed to go immediately to the closest emergency room if the device is used.
The board certified allergy specialists at Black & Kletz Allergy have 3 locations in the Washington, Northern Virginia, and Maryland metropolitan area. We have offices in Washington, DC, McLean, VA (Tysons Corner, VA), and Manassas, VA. All 3 of our offices have on-site parking and the Washington, DC and McLean, VA offices are Metro accessible. The McLean office has a complementary shuttle that runs between our office and the Spring Hill metro station on the silver line. The allergists of Black & Kletz Allergy diagnose and treat both pediatric and adult patients. For an appointment, please call our office or alternatively, you can click Request an Appointment, and we will respond within 24 hours by the next business day. The allergists at Black & Kletz Allergy have been helping patients with food allergies as well as other allergy conditions such as hay fever (i.e., allergic rhinitis), asthma, sinus disease, eczema (i.e., atopic dermatitis), hives (i.e., urticaria), swelling episodes (i.e., angioedema), itching (i.e., pruritus), insect sting allergies, medication allergies, eosinophilic esophagitis, mast cell activation syndrome, and immunological disorders for more than 50 years. If you suffer from allergies, it is our mission to improve your quality of life by reducing or preventing your undesirable and annoying allergy symptoms.
