Anaphylactic Shock:

An immediate and severe allergic response; a shock reaction to a substance. This can result in sudden severe breathing difficulty, severe drop in blood pressure, and/or loss of consciousness. Anaphylactic shock can kill if not treated promptly. Common causes of anaphylaxis include: bee stings in people that are allergic to bees, ingestion of certain foods by people that are allergic to those foods, and drug reactions.