Anaphylaxis, or anaphylactic shock, is an acute allergic reaction which is the result of a hypersensitivity to an allergen. Peanuts and bee stings famously cause anaphylaxis in some people, but a wide variety of allergens can be responsible. Left untreated, anaphylactic shock can be fatal, sometimes in minutes. Fortunately, this type of allergic reaction is extremely rare, and many people become aware that they are at risk for this reaction before they experience an anaphylactic episode, so they are prepared.
In order for anaphylaxis to occur, someone has to be exposed to the allergen at least once before. The body's immune system develops antibodies to that substance, and when the person is exposed again, the immune system goes into hyperdrive, releasing a flood of histamines and other substances in a mistaken attempt to protect the body.
A number of symptoms are associated with anaphylactic shock. The most dangerous is swelling, which causes the airway to constrict. The face of the patient may also become swollen and lumpy, and often an acute skin reaction such as hives emerges. The patient's blood pressure drops while the heart rhythm changes, and the patient may also experience gastrointestinal distress. Vomiting, fainting, dizziness, nausea, and panic are also associated with the reaction.
In some cases, the anaphylaxis is so severe that the patient goes into shock. When this happens, very rapid action must be taken to save the patient's life, because he or she could literally die in minutes from lack of air. The immediate treatment for anaphylactic shock is epinephrine, followed by supportive oxygen therapy and the use of steroids to manage long-term problems associated with the anaphylactic episode.
People who know that they are at risk of anaphylaxis may carry an autoinjector loaded with epinephrine so that in the event of an incident, they can start treatment immediately. Emergency services personnel are still needed, however, and they may inject additional epinephrine along with other drugs. People with allergies are strongly urged to talk to their doctors about severe allergic episodes, to evaluate whether or not they may be at risk for anaphylactic shock, and people who are at risk should instruct coworkers, fellow students, and friends about what to do in an emergency.
Concerns about anaphylaxis are sometimes used to justify restrictive policies in schools and businesses which dictate the foods which people may bring in. For example, some people are highly allergic to peanuts, and rather than run the risk of accidental exposure, administrators may decide that it is safer to simply bar peanuts from the school or workplace to protect someone's safety.