What is anaphylaxis?
Anaphylaxis is a serious allergic reaction that is rapid in onset and may cause death. The reaction can occur a few seconds to as long as an hour after exposure to the allergen. It is a medical emergency, and in most cases it requires immediate treatment and then follow-up care by an allergist. Anaphylaxis is triggered when the immune system overreacts to a normally harmless substance such as food or medicines. The symptoms may be mild to severe and affect various body organ systems.