FOOD ALLERGY OVERVIEW Reactions to food are common, and can be
divided into two categories, those caused by food allergy and
all other reactions. It is important to know the difference
between food allergies and other illnesses or symptoms caused by
foods because the management of each is different. - Food
allergies develop when the body's immune system has an abnormal
reaction to one or more proteins in a food. Food allergies can
lead to serious or even life-threatening allergic reactions. -
Other food reactions are not caused by the immune system. These
reactions cause unpleasant symptoms and are far more common than
food allergies. Examples include lactose intolerance, heartburn
(gastroesophageal reflux), bacterial food poisoning, and
sensitivity to caffeine, just to name a few. This topic
discusses the signs and symptoms of food allergy and testing
that may be recommended to diagnose food allergies. The
avoidance of foods in people with food allergies is discussed
separately. (See "Patient information: Fo