Hypersensitivity reactions are exaggerated or inappropriate immunologic responses occurring in response to an antigen or allergen. Type I, II ...ImmediateHypersensitivityReactionsMedicalReferenceImmediateHypersensitivityReactionsEarnCME/CEcreditforthisarticle1.25CreditsMD/PACME1.25CreditsDOCME1.25CreditsAANP/NPCE1.25CreditsANCC/NurseCE1.25CreditsACPE/PharmacistCEReviewquestions:TakeFreeQuestionsonthisArticleContinuingEducationActivityHypersensitivityreactionsareexaggeratedorinappropriateimmunologicresponsesoccurringinresponsetoanantigenorallergen.TypeI,IIandIIIhypersensitivityreactionsareknownasimmediatehypersensitivityreactionsbecausetheyoccurwithin24hoursofexposuretotheantigenorallergen.ImmediatehypersensitivityreactionsarepredominantlymediatedbyIgE,IgM,andIgGantibodies.Thisactivitydescribesthepathophysiologyoftheimmediatehypersensitivityreactions,reviewstheirevaluationandmanagement,andhighlightstheroleoftheinterprofessionalteaminthemanagementofaffectedpatients.Objectives:Describetheriskfactorsforimmediatehypersensitivityreactions.Reviewthehistoryandphysicalexamfindingsofimmediatehypersensitivityreactions.Outlinetreatmentoptionsforimmediatehypersensitivereactions.Summarizestrategiestoimprovecarecoordinationamongstinterprofessionalteammemberstoimproveoutcomesforpatientsaffectedbyimmediatehypersensitivereactions.IntroductionHypersensitivityreactions(HR)areimmuneresponsesthatareexaggeratedorinappropriateagainstanantigenorallergen.CoombsandGellclassifiedhypersensitivityreactions intofourforms.TypeI,typeII,andtypeIIIhypersensitivityreactionsareknownasimmediatehypersensitivityreactions(IHR)becausetheyoccurwithin24hours.AntibodiesincludingIgE,IgM,andIgGmediatethem.[1]TypeIorAnaphylacticResponseTheanaphylacticresponseismediatedbyIgEantibodiesthatareproducedbytheimmunesysteminresponsetoenvironmentalproteins(allergens)suchaspollens,animaldanders,ordustmites.Theseantibodies(IgE)bindtomastcellsandbasophils,whichcontainhistaminegranulesthatarereleasedinthereactionandcauseinfla