The term “food allergy” applies to immunological reactions characterised by production of IgE antibodies against food. Like other kind of allergies, these reactions are abnormal (because they are not caused by harmful components in the food) and occur only in individuals who have a genetic predisposition to react this way.
Food allergy results in a variety of symptoms: digestive (abdominal pain, vomiting or diarrhoea), cutaneous (urticaria, or just itchy or red skin), respiratory (difficulty in breathing that can be caused by swelling of the throat or larynx lining but also by narrowing of the bronchi), blood circulation related (variable drop in blood pressure, resulting in heart palpitations, dizziness, mental confusion of even loss of consciousness). In the most severe forms (anaphylactic attacks) respiration or the blood circulation can be extensively compromised, endangering life.
Symptoms may occur very quickly (within a few minutes) after eating the food or they can be delayed for a few hours. Usually, the more severe the reaction, the faster the onset.