MenuNewsReferenceSlideshowsQuizzesVideosQuestions&AnswersMedicationsFindanAllergistOverview&FactsSymptoms&TypesDiagnosis&TestsTreatment&CareWhatIsAnAllergicReaction?AllergyBasicsWhoGetsAllergies?AllergiesorCold?AllergyMapAllergyReliefAdvisorChildren'sAllergiesEyeAllergiesCold&FluMapSkinAllergiesFoodAllergiesAsthmaDrugInteractionCheckerSevereAllergiesMoreRelatedTopicsAllergiesA-ZAllergiesReferenceMenuMedicallyReviewedbyNayanaAmbardekar, MDonMarch07,2020ArticlesOnWhatAreAllergies?WhatIsAnAllergicReaction?AllergyBasicsWhoGetsAllergies?Somepeoplesneezelikecrazy.Othersgetitchyhivesorwateryeyes.Butwhateverthereaction,itboilsdowntoonething:allergies.Ifyouhaveallergies,youhavelotsofcompany.Asmanyas30%ofU.S.adultsand40%ofchildrenareinthesameboatasyou.Whileyourproblemmayseemtostartinthenoseortheeyes,allergiesactuallycomefromanimmunesystemrunwild.Learningwhythesereactionshappencanhelpyoukeepthingsundercontrolandfeel better.WhyAllergicReactionsHappenYourimmunesystemhasanimportantjob:todefendyourbodyfrominvaderssuchasbacteriaandvirusesthatmeanyouharm.Butwhenitmakeswaronsubstancesitshouldn’t,that’sanallergy.Peanuts,eggs,orpollen,forexample,cantriggerreactions.Theyarecalledallergens.Duringareaction,yourimmunesystemreleasesantibodies.Theseareproteinsthatdeliveramessagetocells:Stopthatsubstance!Thecellsthensendouthistamine,whichcausesbloodvesselstoexpand,andotherchemicals,andthesetriggertheallergysymptoms.Theseantibodiesaresingled-minded.Eachonetargetsonlyonetypeofallergen.Thatexplainswhysomeonemightbeallergictopeanutsbutnottoeggs.Youcancomeintocontactwithallergensinmanyways:throughtheskin,eyes,nose,mouth,orstomach.Thiscancauseyoursinusestoclogup,inflameyourskin,makeithardertobreathe,orcausestomachproblems.WhatThingsMostOftenCauseanAttack?Whydosomepeoplehavesuchbadallergiesandothersdon’t?Expertsdon’thavealltheanswers,buttheysayfamilyhistoryisimportant.Somecommonallergensinclude:AnimaldanderBeestingsCertainmedicationssuchaspenicillinDustmitesFoods--particularlypeanuts,treenuts,fish,s