Q: What I don’t understand is: how does an expert decide whether a food allergy is “life-threatening” or not? This issue comes up frequently, such as when preparing forms for daycare or schools.
Dr. Sharma: Your question is a great one because it points out a major limitation of our currently available food allergy tests, and is the reason research is underway to identify more predictive testing.
Unfortunately, neither skin tests nor blood tests for Immunoglobulin E (IgE are the allergic antibodies) can accurately predict how severe a future food allergy reaction might be. For example, even though two people may have the same blood test level to their food allergen, after an accidental exposure, one might have a life-threatening reaction and the other a mild reaction.
Certain people are thought to be at higher risk of a life-threatening reaction; for instance, those with asthma, a previous anaphylactic reaction (the serious form of allergic reaction), or an allergy to peanut, tree nuts or shellfish.
But, food allergy is highly unpredictable, and even people with a mild history can go on to have a life-threatening reaction. At the moment, we have to presume that all food allergies have the potential to be life-threatening and patients should take proper precautions such as reading all food labels and carrying epinephrine auto-injectors.
Dr. Sharma is an allergist, clinical researcher and Assistant Professor of Pediatrics. He is Associate Chief of the Division of Allergy and Immunology at Children’s National Medical Center in Washington D.C. and Director of the Food Allergy Program. He co-authors “The Food Allergy Experts” column in the American Edition of Allergic Living  magazine. Questions submitted below will be considered for answer in the magazine.