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Anaphylaxis (cont.)

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What are common causes of anaphylaxis?

The major causes of anaphylaxis include medications, foods, drugs, latex, and insect bites or stings (wasps, yellow jackets, hornets, honeybees, and fire ants), and latex. The causes of anaphylaxis are divided into two major groups:

IgE-mediated: This form requires an initial sensitizing exposure (an exposure to the substance that will later trigger the anaphylaxis) and then occurs on a subsequent exposure. It involves the coating of mast cells and basophils (cells in the blood and tissue that secrete mediators, the substances that cause allergic reactions) by an antibody called IgE, and the subsequent release of chemical mediators upon re-exposure. IgE-mediated anaphylaxis can occur with foods, drugs, latex, and insect stings. Although it may appear that IgE-mediated anaphylaxis occurs upon a first exposure to a food, drug, or insect sting, there must have been a prior sensitization from a previous exposure, which is often unknown. One may not remember an uneventful sting. The previous exposure to a food may not be recalled; it may occur in utero, through breast milk, or through the skin, particularly in individuals with eczema (atopic dermatitis).

Non-IgE-mediated: These reactions have the same symptoms as true anaphylaxis but do not require an IgE immune reaction. They are usually caused by the direct stimulation of the mast cells and basophils. In the past, they have been termed "anaphylactoid reactions." The same mediators are released as with IgE-mediated anaphylaxis, and the same effects are produced. This reaction can happen on initial, as well as subsequent, exposures, since no sensitization is required. This type of reaction usually occurs with medications. A common cause of a non-IgE-mediated reaction is IV contrast used in imaging studies.

Medically Reviewed by a Doctor on 7/21/2016


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