Anaphylaxis
Suchela Janwitayanujit MD*
Affiliation : * Department of Medicine, Faculty of Medicine, Ramathibodi Hospital
Anaphylaxis must always be considered a medical emergency. While classic anaphylaxis needs spe-
cific antigen to trigger IgE antibody-mediated reaction, idiopathic anaphylaxis spontaneously occurs with
no external allergen. Anaphylactoid are not mediated by antigen-antibody but result from substances acting
directly on mast cells and basophils.
Incidence of anaphylaxis is 21 per 100,000 person-years with fatality in about 0.65% of cases. Food
is the most frequent cause of anaphylaxis in children while insect sting is the most common cause in adults.
Epinephrine is the first pharmacological treatment. Secondary measures include circulatory support, H1 and
H2 antagonists, bronchodilators if necessary and probably corticosteroids. Since life-threatening manifesta-
tions may recur during the recurrent phase, it may be necessary to observe the patients for up to 48 hours after
apparent recovery from an anaphylactic episode.
Keywords : Anaphylaxis, Anaphylactoid, Idiopathic anaphylaxis, Allergic reaction, Uniphasic, Biphasic, Paotracted, Epinephrine
