A food allergy is an adverse immune reaction to a particular food, most commonly mediated by immunoglobulin E (IgE) antibodies against specific food proteins. On exposure, the immune system releases histamine and other mediators, producing symptoms that range from itching, hives, and swelling of the lips and face to vomiting, breathing difficulty, and anaphylaxis — a rapid, potentially fatal systemic reaction treated with adrenaline. Common triggers include peanuts, tree nuts, milk, eggs, fish, shellfish, soy, and wheat. Diagnosis relies on clinical history supported by skin-prick or blood tests and, where needed, supervised food challenges. Management means strict avoidance of the trigger food, careful label reading, and carrying emergency medication. Food allergy must be distinguished from food intolerance, which does not involve the immune system.