An estimated 11 million Americans, suffer from food allergies, which accounts for roughly 20,000 emergency room visits annually. Unfortunately, as many as 200 people die from food-allergy reactions every year.

Food allergy and food intolerance are not the same.  Food intolerance is an undesirable reaction to a food that does not involve food related immune response.  The most common food intolerance is lactose intolerance, in which case, the individual lacks an enzyme that is needed to digest milk sugar.  When milk products are ingested, symptoms such as gas, bloating, and abdominal pain may occur.  However, if only a small amount of milk is consumed, he or she may avoid symptoms.  A food allergy occurs when a person with particular genetic predisposition produces specific immunoglobulin E (allergy antibody) to the protein of a certain food.  When those antibodies react with certain food, histamine and other chemicals are released from body and cause allergic symptoms.  Even if you only eat a small amount of an allergy-causing food, allergic reaction can be triggered.

Food-allergy reactions can affect several body systems such as the gastrointestinal tract (abdominal pain, diarrhea, nausea, vomiting), skin (hives, eczema), respiratory system (swelling of the throat or mouth, wheezing, difficulty breathing), and cardiovascular system (drop in blood pressure, feeling of impending doom, loss of consciousness).

Although an individual could be allergic to any food, tree nuts, eggs, soy, milk, wheat, fish, and shellfish account for 90% of all food-allergic reactions.  Peanuts are the leading cause of anaphylaxis, followed by shellfish, fish, tree nuts and eggs.  It has been recommended that peanut-allergic patients avoid tree nuts (pecans, walnuts, almonds, etc), and vice versa, as an extra precaution.

In addition to food, medications, stinging insects, latex, and even extreme temperature change can cause urticaria or anaphylaxis.   Foods suspected of causing acute (sudden) hives are often identified by their ingestion on several occasions in proximity to the development of skin rash.  Chronic hives, which lasts more than 3 months, is not commonly caused by food allergy alone.

Urticaria (hives) and anaphylaxis generally occur within minutes or can be delayed up to 2 hours after ingestion of the offending food.  Non-generalized allergic reactions are treated with a high dose antihistamine, while anaphylaxis requires immediate medical treatment with epinephrine and possibly corticosteroids in addition to the antihistamines.  Unfortunately, strict avoidance of the allergy-causing food is the only way to avoid a reaction.