Many people refer to food allergies when they probably have a food intolerance. A food intolerance can cause some of the same signs and symptoms as a food allergy, so people often confuse the two. So what’s the difference between the two? In some cases, an allergic reaction to a food can be severe or life-threatening (anaphylaxis). In contrast, food intolerance symptoms are generally less serious and often limited to digestive problems. Food Alleries The main thing that defines a food allergy is that the body thinks one of the proteins in the food is harmful and thus triggers an immune response by producing histamine and usually pretty immediate. It becomes.