Anaphylaxis should be suspected if any of the following suddenly occur without explanation: Shock Respiratory symptoms (eg, dyspnea, stridor, wheezing) Two or more other manifestations of possible anaphylaxis (eg, angioedema, rhinorrhea, GI symptoms) Risk of rapid progression to shock leaves no time for testing, although mild equivocal cases can be confirmed by measuring serum levels of tryptase (preferably within 2 hours of the reaction).