anaphylactic shock

 a severe form of physiological shock, often having a fatal outcome, caused by an extreme immunological reaction to antigens. It is a severe form of anaphylaxis{2}, and is characterized by smooth muscle contraction and capillary dilation throughout the body, initiated by antibodies of the IgE class. It is usually seen when an antigen to which a person has become hypersensitized is injected intravenously or subcutaneously. It is also called generalyzed anaphylaxis or systemic anaphylaxis, and sometimes anaphylaxis.  [PJC]