Anaphylaxis is a life-threatening condition normally caused by an allergic reaction. The most common allergies known to induce anaphylaxis are shellfish, peanut and egg allergies, along with insect sting allergies and allergies to certain drugs. When your body encounters an allergen, it sets off an immune system response. The response releases a number of chemicals that cause allergic symptoms. In rare cases, anaphylaxis is one of these symptoms.

Anaphylaxis can be recognized by certain characteristic symptoms. There's typically a drastic drop in blood pressure along with an unusually rapid pulse. Airways become constricted, making it difficult to breathe. Some people get dizzy and can even lose consciousness. Swelling and hives are common, especially around the lips and mouth. Skin can turn pale or bluish, and nausea, vomiting and diarrhea are typical symptoms, as well.

When anaphylaxis sets in, immediate care is required. With early and appropriate intervention, anaphylaxis can pass within a few hours. However, if the anaphylaxis has already progressed to a serious stage before medical help is obtained, it can take a few days for all of the symptoms of anaphylaxis to go away. And if no medical attention is available, anaphylaxis can cause death within minutes or hours after onset. People who know they're prone to anaphylactic allergic reactions typically carry epinephrine autoinjectors with them; when they recognize the onset of anaphylaxis, they can stave off a more serious attack by injecting themselves immediately. Medical care is still required after an epinephrine injection, however. People without epinephrine should call paramedics as soon as they realize that they're going into anaphylactic shock. The paramedics can administer necessary drugs en route to the hospital. Once you've had one anaphylactic reaction to an allergen, you're more likely to experience another attack in the future.