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Allergies Health Center

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Allergies and Anaphylaxis

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Anaphylaxis is a serious, potentially life-threatening allergic response that is marked by swelling, hives, lowered blood pressure, and dilated blood vessels. In severe cases, a person will go into shock. If anaphylactic shock isn't treated immediately, it can be fatal.

This condition occurs when the immune system develops a specific allergen fighting antibody (called immunoglobulin E or IgE) that drives an inappropriate or exaggerated reaction toward a substance that is normally harmless, such as food. Your body may not react upon initial exposure but may produce antibodies with later exposures. When you are exposed to the substance later, the binding of the allergen to antibodies can lead to the presence of a large amount of a substance called histamine, which can then lead to the symptoms described above.

What Are the Symptoms of Anaphylaxis?

Anaphylaxis may begin with severe itching of the eyes or face and, within minutes, progress to more serious symptoms. These symptoms include swallowing and breathing difficulties, abdominal pain, cramps, vomiting, diarrhea, hives, and angioedema (swelling similar to hives, but the swelling is beneath the skin instead of on the surface).

If you have anaphylaxis, seek emergency medical attention immediately. The condition can quickly result in an increased heart rate, sudden weakness, a drop in blood pressure, shock, and ultimately unconsciousness and death.

What Are the Common Triggers of Anaphylaxis?

Food is generally the most common cause of anaphylaxis. Common food triggers include nuts, shellfish (shrimp, lobster), dairy products, egg whites, and sesame seeds. Wasp or bee stings are also common causes of anaphylaxis.

Additionally, exercise can trigger anaphylaxis if the activity occurs after eating allergy-provoking food.

Medications are also a common cause of anaphylaxis.

Pollens and other inhaled allergens (allergy-causing substances) rarely cause anaphylaxis.

Some substances can cause reactions -- called anaphylactoid reactions -- that are similar to and just as serious as anaphylaxis, but do not involve immunoglobulin E antibodies. The most common triggers include iodine-containing dyes that can be seen on X-rays, aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil, opioids, blood transfusions, and exercise.

How Is Anaphylaxis Diagnosed?

Anaphylaxis is diagnosed based on its symptoms. People with a history of allergic reactions may be at greater risk for developing a severe reaction in the future.

Skin testing may help confirm the substances that cause severe allergic reactions.

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