ForYouNews&PerspectiveDrugs&DiseasesCME&EducationAcademyVideoDecisionPointEdition:ENGLISHDEUTSCHESPAÑOLFRANÇAISPORTUGUÊSLogInSignUpIt'sFree!Edition:ENGLISHDEUTSCHESPAÑOLFRANÇAISPORTUGUÊSRegisterLogInNoResultsNoResultsForYouNews&PerspectiveDrugs&DiseasesCME&EducationAcademyVideoDecisionPointclosePleaseconfirmthatyouwouldliketologoutofMedscape.Ifyoulogout,youwillberequiredtoenteryourusernameandpasswordthenexttimeyouvisit.LogoutCancelhttps://profreg.medscape.com/px/getpracticeprofile.do?method=getProfessionalProfile&urlCache=aHR0cDovL2VtZWRpY2luZS5tZWRzY2FwZS5jb20vYXJ0aWNsZS8xMzYyMTctY2xpbmljYWw=processing....Drugs&Diseases>Allergy&ImmunologyImmediateHypersensitivityReactions ClinicalPresentationUpdated:Aug11,2020Author:BeckyBuelow,MD,MS;ChiefEditor:MichaelAKaliner,MD more...ShareEmailPrintFeedbackCloseFacebookTwitterLinkedInGoogle+SectionsImmediateHypersensitivityReactionsSectionsImmediateHypersensitivityReactionsOverviewBackgroundPathophysiologyEpidemiologyShowAllPresentationHistoryPhysicalCausesShowAllDDxWorkupLaboratoryStudiesOtherTestsShowAllTreatmentMedicalCareConsultationsDietShowAllMedicationMedicationSummaryVasopressorsBronchodilatorsCorticosteroidsHistamine1receptorantagonists(antihistamines)Histamine2receptorantagonists(H2antagonists)LeukotrieneinhibitorsImmunomodulatorsMonoclonalAntibodies5-LipoxygenaseInhibitorsShowAllFollow-upDeterrence/PreventionPatientEducationShowAllTablesReferencesPresentationHistoryHistoryfindingsvarydependingonwhichorgansystemsareaffected.AnaphylaxisPatientsmayreportskinitching,localizedordiffusepruritus,dizziness,faintness,anddiaphoresis.Difficultybreathingcanresultfromangioedemaofthepharyngealtissue,frombronchoconstriction,orfromboth.PatientsmayalsoreportGIsymptoms,includingnausea,vomiting,diarrhea,andabdominalcramping.Patientsmayexperienceuterinecrampingorurinaryurgency.Patientscanhaveasuddenonsetofrespiratoryand/orcirculatorycollapseandgointoanaphylacticshock.Symptomsusuallybeginwithinminutesofallergenexposure(e.g.,drugadministr