Anaphylaxis

The most severe allergic reaction is anaphylaxis. Anaphylaxis, or anaphylactic shock, is a severe, sudden and systemic, usually multi-organ, allergic reaction that can be fatal within minutes, either through swelling that shuts off airways or through a dramatic drop in blood pressure. It requires immediate medical intervention.

Anaphylaxis occurs in allergic individuals when they are exposed to an allergen, almost always a protein that is treated by the immune system as a foreign substance. Some anaphylactic reactions may involve only one organ, such as the respiratory tract or skin. However, often several systems are affected simultaneously, including the upper and lower respiratory tracts, cardiovascular system, and gastrointestinal tract.

Swelling of the mouth, tongue, lips, skin and eyelids are characteristic for anaphylaxis. In serious cases, the reaction progresses to vomiting, wheezing, breathing difficulties and even cardiovascular collapse. If not treated promptly, anaphylactic reactions may be fatal.

Many anaphylactic reactions are triggered by foodstuffs, but wasp or bee stings, certain drugs, latex, exercise and unknown causes (idiopathic anaphylaxis) can also cause this acute and potentially life-threatening reaction.
Fortunately, effective treatment is available, so death from anaphylaxis can be prevented in most cases. Still, deaths occur because initial symptoms of anaphylaxis go unrecognised or because treatment is not prompt enough or unavailable at the time of the reaction.

Treating Anaphylaxis

Avoidance of identified allergens is critical for people who suffer from severe allergies. However, total avoidance is not always possible, either because of the nature of some allergens (e.g. pollen) or accidental exposure to hidden allergens (e.g. food).

People susceptible to anaphylaxis should educate themselves about allergen avoidance. It is also important that the allergic person's family, friends—and, in the case of children—teachers and schools know about and understand the disease so that they can aid in preventing anaphylaxis.

Once anaphylaxis has begun, the treatment of choice is an immediate injection of epinephrine, also known as adrenaline, which has a fast onset of activity (within 5 to 10 minutes after injection), followed by emergency medical attention. Epinephrine autoinjectors are the recommended devices to use since they can be applied by the patients themselves and can be carried with them at all times. Transport to a medical facility is necessary even if, due to the epinephrine injection, the initial symptoms have subsided, since a second reaction may occur hours after allergen exposure.

Many physicians also recommend that antihistamines be administered to lessen the symptoms of an allergic reaction, but antihistamines should be taken only in addition to epinephrine and should not be considered a substitute for it. Only epinephrine can halt the potentially deadly effects of anaphylaxis.

The mainstays of treating anaphylaxis are avoidance of the allergen when possible and emergency administration of epinephrine when necessary.