Hives and Anaphylaxis in Food Allergy

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Category: Food Allergy Published on Thursday, 03 July 2008 Written by Yong Tsai, MD
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An estimated 11 million Americans suffer from food allergies, which accounts for roughly 20,000 emergency room visits annually.  And, unfortunately, as many as 200 people die from food-allergy reactions each year.   But, food-allergy and 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, where the individual lacks an enzyme 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 the symptoms.

A food allergy occurs when a person with particular genetic predisposition produces specific immunoglobulin E (an allergy antibody) to the protein of a certain food. When those antibodies react with a certain food, histamine and other chemicals are released from the body and cause allergic symptoms. Even when you only eat a small amount of allergy causing food, a reaction can be triggered.  Although an individual could be allergic to any food, the following foods-tree nuts, eggs, soy, milk, wheat, fish and shellfish-account for 90 percent of all food-allergic reactions.

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).

Urticaria (hives) is an outbreak of red bumps of patches called "wheals" that appear on the skin, produced by the presence of histamine and other chemicals. .  Foods suspected of causing acute (sudden) hives are often identified by their ingestion on several occasions followed by a skin rash.
Chronic hives, which lasts more than three months, is not commonly just caused by a food allergy.

The most dangerous allergic reaction is known as "anaphylaxis" and can produce shortness, wheezing, airway swelling, increased heart rate, loss of consciousness, and even death.  Both usually occur within minutes or can be delayed up to two hours after ingestion of the offending food.  Peanuts are the leading cause of anaphylaxis, followed by shellfish, fish, tree nuts, and eggs. It is recommended that peanut-allergic patients avoid all 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.

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