Anaphylaxis-Causes of Anaphylaxis

The word anaphylaxis was coined when scientists tried to protect dogs against a poison by immunizing them with small doses. Far from being protected, the dogs died suddenly when they got the poison again. The word used for protection by immunization is ''prophylaxis'', so the scientists coined the word ''anaphylaxis'' to mean the opposite of protection.

The word anaphylaxis was coined when scientists tried to protect dogs against a poison by immunizing them with small doses. Far from being protected, the dogs died suddenly when they got the poison again. The word used for protection by immunization is ''prophylaxis'', so the scientists coined the word ''anaphylaxis'' to mean the opposite of protection. What the scientists saw in the dogs helped them to understand that the same can happen in humans. This helped us to understand asthma and other allergies too, because they work in a similar way.

Anaphylaxis refers to a severe allergic reaction in which prominent dermal and systemic signs and symptoms manifest. The full-blown syndrome includes urticaria (hives) and/or angioedema with hypotension and bronchospasm. The classic form, described in 1902, involves prior sensitization to an allergen with later re-exposure, producing symptoms via an immunologic mechanism. An anaphylactoid reaction produces a very similar clinical syndrome but is not immune-mediated. Treatment for both conditions is similar, and this article uses the term anaphylaxis to refer to both conditions unless otherwise specified.


An anaphylactic reaction may begin with a tingling sensation, itching, or a metallic taste in the mouth. Other symptoms can include hives, a sensation of warmth, wheezing or other difficulty breathing, coughing, swelling of the mouth and throat area, vomiting, diarrhea, cramping, a drop in blood pressure, and loss of consciousness. These symptoms may begin within several minutes to two hours after exposure to the allergen, but life-threatening reactions may get worse over a period of several hours.

Causes of Anaphylaxis


Some drugs (polymyxin, morphine, x-ray dye, and others) may cause an anaphylactoid reaction (anaphylactic-like reaction) on the first exposure. This is usually due to a toxic reaction, rather than the immune system mechanism that occurs with "true" anaphylaxis. The symptoms, risk for complications without treatment, and treatment are the same, however, for both types of reactions.

Anaphylaxis in children often results from food allergies. Food allergies are most likely to develop in the first three years of life, when many foods are introduced into a child''s diet. Allergies to hen''s egg, peanuts, cow''s milk, soy, fish, and wheat are among the most common food allergies that children develop. In children over the age of three years, peanuts are the most common allergen. Children often outgrow allergies to milk, eggs, and soybeans. However, allergies to peanuts, other tree nuts, fish and seafood tend to persist.

Tissues in different parts of the body release histamine and other substances. This causes constriction of the airways, resulting in wheezing, difficulty breathing, and gastrointestinal symptoms such as abdominal pain, cramps, vomiting, and diarrhea. Histamine causes the blood vessels to dilate (which lowers blood pressure) and fluid to leak from the bloodstream into the tissues (which lowers the blood volume). These effects result in shock. Fluid can leak into the alveoli (air sacs) of the lungs, causing pulmonary edema.


Approximately 20 deaths have been identified each year (one each year for each 3 million of population). There will have been additional undetected fatal reactions, such as those to antibiotics taken at home, in which autopsy findings are commonly limited to the infection (often with asthma) for which the antibiotic was taken. lists the UK anaphylactic deaths over an approximately 10-year period.

Medicines, such as antibiotics, aspirin, over-the-counter pain relievers, allergy shots and contrast dye for radiologic procedures.

Latex or rubber found in surgical gloves, medical supplies and many products in your home.

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