The best method is the "elimination diet." Your child goes on a strict diet, eating only what you know does not cause allergic reactions. Every week, you add one new food, observing for any symptoms. If you notice that he's allergic to it, you remove it and then revert to the previous diet for three days. Then, you introduce another new food. This goes on for several weeks or … [Read more...] about How do I know if my child has a food allergy?