ABSTRACT
Anaphylaxis is an exaggerated response to a substance to which an individual has become sensitized in which histamine, serotonin and other vasoactive substances are released. This causes symptoms which can include pruritus, erythema, flushing, urticaria, angio-oedema, nausea, diarrhoea, vomiting, laryngeal oedema, bronchospasm, hypotension, cardiovascular collapse and death. Anaphylactic reactions usually begin within 5-10 minutes of exposure and the full reaction usually evolves within 30 minutes. Anaphylactic and anaphylactoid reactions are clinically indistinguishable and managed in the same way. They have a different immunological mechanism.
