<p>Anaphylaxis is a common presentation seen in emergency departments (EDs), yet due to a lack of consensus over definition its true prevalence remains unknown (Moneret-Vautrin et al 2005). There is agreement however that the presence of the life-threatening features of respiratory difficulty and hypotension constitute a severe reaction (Hathaway 2005, Lieberman et al 2005, Moneret-Vautrin et al 2005).</p>