It's rare, but allergies can be deadly. Anaphylaxis, a severe whole body reaction, can lead to suffocation or heart failure. According to research, anaphylactic reactions are responsible for approximately 1,500 deaths in the U.S. each year - and 88 percent of those involve sudden cardiovascular collapse. Anaphylaxis typically occurs after a second exposure to an allergen. This is because the first exposure causes the immune system to create antibodies to the triggering substance - think peanuts, bee stings, or mold. The second exposure sends those antibodies into action, causing a cascade of bodily reactions that lead to loss of blood pressure, hives, constriction of airways, and gastrointestional problems. The skin and respiratory system are most likely to be affected, followed by the gastrointestinal tract and circulatory and nervous systems. The most common triggers of anaphylaxis are foods such as peanuts, wheat, tree nuts, shellfish, fish, milk and eggs, medications, including antibiotics, aspirin, ibuprofen, and other anti-inflammatory drugs, as well as insect venom from stings have also been known to trigger an anaphylactic reaction. If you are highly allergic to any substance and have experienced an anaphylactic reaction, or if you are at risk due to genetics or past health history, you should have an "allergy action plan" - carry an epinephrine injection with you at all times, wear a medic alert bracelet that explains your potential condition, and in a crisis, call 911 immediately. EMTs may give antihistamines and corticosteroids intravenously to reduce airway inflammation and a beta agonist to relieve breathing symptoms. To learn more about allergic reactions, check out other videos in this series.