Although frequently suspected, food hypersensitivities occur in only 2 to 5% of the general population. These occur because food processed in the gut escapes immunoregulatory mechanisms that usually effectively prevent these reactions from developing. When they fail, hypersensitivity, which may be either IgE- or non-IgE-mediated results. Although the events that lead to these reactions are initially in the gut, patients may experience multisystemic symptoms (e.g. anaphylaxie). Or, symptoms may be more focused affecting only the skin (e.g. urticaria/angioedema and atopic dermatitis) or the respiratory tract (e.g. upper or lower airway symptoms). Non-IgE-mediated reactions most often involve the gastrointestinal tract. Most commonly, infants suffer from enterocolitis, milk-induced colitis, or food-induced enteropathy, and older children are most likely to experience allergie eosinophilic gastroenteritis.