A few times a month I see new patients who report that they or their child has a red dye allergy. When asked what happens when they consume things with red dye, what I typically hear is there is a behavior change, like hyperactivity or aggression but not symptoms of anaphylaxis like hives or trouble breathing. Red Dye #40 does not contain any protein which means it cannot trigger IgE-induced or “allergic” reactions but the foods and products that contain red dye like candy, Dr. Pepper and fruit punch certainly can cause behavior changes or other symptoms of intolerance. There is a particular red dye primarily used in cosmetic products called carmine or natural red #4 that is made from dried pulverized insects and it can cause allergic contact reactions but rarely anaphylaxis. Red dye is found in thousands of prepared and packaged foods, cosmetics and medications and is very hard to avoid. So, if you want to find out if you or a loved one has a red dye allergy see a board certified allergist.