Influenza (flu) - Symptoms and causes - Mayo Clinic

Influenza is a viral infection that attacks your respiratory system — your nose, throat and lungs. Influenza is commonly called the flu, ... COVID-19:Advice,updatesandvaccineoptions FindoutaboutCOVID-19,COVID-19vaccines,andMayoClinicpatientandvisitorupdates. Skiptositenavigation SkiptoContent ThiscontentdoesnothaveanEnglishversion.ThiscontentdoesnothaveanArabicversion. SectionsforInfluenza(flu)Symptoms&causesDiagnosis&treatmentDoctors&departments Print OverviewInfluenzaisaviralinfectionthatattacksyourrespiratorysystem—yournose,throatandlungs.Influenzaiscommonlycalledtheflu,butit'snotthesameasstomach"flu"virusesthatcausediarrheaandvomiting. Formostpeople,thefluresolvesonitsown.Butsometimes,influenzaanditscomplicationscanbedeadly.Peopleathigherriskofdevelopingflucomplicationsinclude: Youngchildrenunderage5,andespeciallythoseunder6months Adultsolderthanage65 Residentsofnursinghomesandotherlong-termcarefacilities Pregnantwomenandwomenuptotwoweeksaftergivingbirth Peoplewithweakenedimmunesystems NativeAmericans Peoplewhohavechronicillnesses,suchasasthma,heartdisease,kidneydisease,liverdiseaseanddiabetes Peoplewhoareveryobese,withabodymassindex(BMI)of40orhigher Thoughtheannualinfluenzavaccineisn't100%effective,it'sstillyourbestdefenseagainsttheflu.Products&ServicesBook:MayoClinicBookofHomeRemediesCoronavirusmap:TrackingthetrendsU.S.COVID-19VaccineTracker:Seeyourstate'sprogressShowmoreproductsfromMayoClinic SymptomsAtfirst,theflumayseemlikeacommoncoldwitharunnynose,sneezingandsorethroat.Butcoldsusuallydevelopslowly,whereastheflutendstocomeonsuddenly.Andalthoughacoldcanbeabother,youusuallyfeelmuchworsewiththeflu. Commonsignsandsymptomsofthefluinclude: Fever Achingmuscles Chillsandsweats Headache Dry,persistentcough Shortnessofbreath Tirednessandweakness Runnyorstuffynose Sorethroat Eyepain Vomitinganddiarrhea,butthisismorecommoninchildrenthanadults Relatedinformation COVID-19andflu:Similaritiesanddifferences WhentoseeadoctorMostpeoplewhogettheflucantreatthemselvesathomeandoftendon'tneedtoseeadoctor. Ifyouhaveflusymptomsandareatriskofcomplications,seeyourdoctorrightaway.Takingantiviraldrugsmayreducethelengthofyourillnessandhelppreventmore-seriousproblems. Ifyouhaveemergencysignsandsymptomsoftheflu,getmedicalcarerightaway.Foradults,emergencysignsandsymptomscaninclude: Difficultybreathingorshortnessofbreath Chestpain Ongoingdizziness Seizures Worseningofexistingmedicalconditions Severeweaknessormusclepain Emergencysignsandsymptomsinchildrencaninclude: Difficultybreathing Bluelips Chestpain Dehydration Severemusclepain Seizures Worseningofexistingmedicalconditions MoreInformationFlu:Whentoseeadoctor?   Thereisaproblemwith informationsubmittedforthisrequest.Review/updatethe informationhighlightedbelowandresubmittheform. FromMayoClinictoyourinbox Signupforfree,andstayuptodateonresearchadvancements,healthtipsandcurrenthealthtopics,likeCOVID-19,plusexpertiseonmanaginghealth. Email ErrorEmailfieldisrequired ErrorIncludeavalidemailaddress LearnmoreaboutMayoClinic’suseofdata. 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Sorrysomethingwentwrongwithyoursubscription Please,tryagaininacoupleofminutes Retry RequestanAppointmentatMayoClinic CausesInfluenzavirusestravelthroughtheairindropletswhensomeonewiththeinfectioncoughs,sneezesortalks.Youcaninhalethedropletsdirectly,oryoucanpickupthegermsfromanobject—suchasatelephoneorcomputerkeyboard—andthentransferthemtoyoureyes,noseormouth. Peoplewiththevirusarelikelycontagiousfromaboutadaybeforesymptomsappearuntilaboutfivedaysaftertheystart.Childrenandpeoplewithweakenedimmunesystemsmaybecontagiousforaslightlylongertime. Influenzavirusesareconstantlychanging,withnewstrainsappearingregularly.Ifyou'vehadinfluenzainthepast,yourbodyhasalreadymadeantibodiestofightthatspecificstrainofthevirus.Iffutureinfluenzavirusesaresimilartothoseyou'veencounteredbefore,eitherbyhavingthediseaseorbygettingvaccinated,thoseantibodiesmaypreventinfectionorlessenitsseverity.Butantibodylevelsmaydeclineovertime. Also,antibodiesagainstinfluenzavirusesyou'veencounteredinthepastmaynotprotectyoufromnewinfluenzastrainsthatcanbeverydifferentvirusesfromwhatyouhadbefore. RiskfactorsFactorsthatmayincreaseyourriskofdevelopingthefluoritscomplicationsinclude: Age.Seasonalinfluenzatendstotargetchildren6monthsto5yearsold,andadults65yearsoldorolder. Livingorworkingconditions.Peoplewholiveorworkinfacilitieswithmanyotherresidents,suchasnursinghomesormilitarybarracks,aremorelikelytodeveloptheflu.Peoplewhoarestayinginthehospitalalsoareathigherrisk. Weakenedimmunesystem.Cancertreatments,anti-rejectiondrugs,long-termuseofsteroids,organtransplant,bloodcancerorHIV/AIDScanweakentheimmunesystem.Thiscanmakeiteasiertocatchthefluandmayalsoincreasetheriskofdevelopingcomplications. Chronicillnesses.Chronicconditions,includinglungdiseasessuchasasthma,diabetes,heartdisease,nervoussystemdiseases,metabolicdisorders,anairwayabnormality,andkidney,liverorblooddisease,mayincreasetheriskofinfluenzacomplications. Race.NativeAmericanpeoplemayhaveanincreasedriskofinfluenzacomplications. Aspirinuseunderage19.Peoplewhoareyoungerthan19yearsofageandreceivinglong-termaspirintherapyareatriskofdevelopingReye'ssyndromeifinfectedwithinfluenza. Pregnancy.Pregnantwomenaremorelikelytodevelopinfluenzacomplications,particularlyinthesecondandthirdtrimesters.Womenaremorelikelytodevelopinfluenza-relatedcomplicationsuptotwoweeksafterdeliveringtheirbabies. Obesity.Peoplewithabodymassindex(BMI)of40ormorehaveanincreasedriskofflucomplications. ComplicationsIfyou'reyoungandhealthy,thefluusuallyisn'tserious.Althoughyoumayfeelmiserablewhileyouhaveit,thefluusuallygoesawayinaweekortwowithnolastingeffects.Butchildrenandadultsathighriskmaydevelopcomplicationsthatmayinclude: Pneumonia Bronchitis Asthmaflare-ups Heartproblems Earinfections Acuterespiratorydistresssyndrome Pneumoniaisoneofthemostseriouscomplications.Forolderadultsandpeoplewithachronicillness,pneumoniacanbedeadly. Prevention FluvaccinesatMayoClinic MayoClinicoffersflushotsinArizona,FloridaandMinnesota. LearnmoreabouthowtogetyourflushotatMayoClinic TheCentersforDiseaseControlandPrevention(CDC)recommendsannualfluvaccinationforeveryoneage6monthsorolder.Thefluvaccinecanreduceyourriskofthefluanditsseverityandlowertheriskofhavingseriousillnessfromthefluandneedingtostayinthehospital. Fluvaccinationisespeciallyimportantthisseasonbecausethefluandcoronavirusdisease2019(COVID-19)causesimilarsymptoms.FluvaccinationcouldreducesymptomsthatmightbeconfusedwiththosecausedbyCOVID-19.Preventingthefluandreducingtheseverityoffluillnessandhospitalizationscouldalsolessenthenumberofpeopleneedingtostayinthehospital. ItmaybepossibletogetaCOVID-19vaccineatthesametimeasyourfluvaccine. Thisyear'sseasonalfluvaccineprovidesprotectionfromthefourinfluenzavirusesthatareexpectedtobethemostcommonduringtheyear'sfluseason.Thisyear,thevaccinewillbeavailableasaninjectionandasanasalspray. Thenasalsprayisn'trecommendedforsomegroups,suchas: Childrenunder2 Adults50andolder Pregnantwomen Childrenbetween2and17yearsoldwhoaretakingaspirinorasalicylate-containingmedication Peoplewithweakenedimmunesystems Kids2to4yearsoldwhohavehadasthmaorwheezinginthepast12months Ifyouhaveaneggallergy,youcanstillgetafluvaccine. Relatednews MayoClinicQ&Apodcast:Timeforyourfluvaccine-RelatednewsMayoClinicQ&Apodcast:TimeforyourfluvaccineFactsaboutthefluvaccine,COVID-19-RelatednewsFactsaboutthefluvaccine,COVID-19 MayoClinicMinute:Whygettingvaccinatedforthefluisdoublyimportantthisseason ControllingthespreadofinfectionTheinfluenzavaccineisn't100%effective,soit'salsoimportanttotakeseveralmeasurestoreducethespreadofinfection,including: Washyourhands.Washingyourhandsoftenwithsoapandwaterforatleast20secondsisaneffectivewaytopreventmanycommoninfections.Orusealcohol-basedhandsanitizersifsoapandwateraren'tavailable. Avoidtouchingyourface.Avoidtouchingyoureyes,noseandmouth. Coveryourcoughsandsneezes.Coughorsneezeintoatissueoryourelbow.Thenwashyourhands. Cleansurfaces.Regularlycleanoften-touchedsurfacestopreventspreadofinfectionfromtouchingasurfacewiththevirusonitandthenyourface. Avoidcrowds.Thefluspreadseasilywhereverpeoplegather—inchildcarecenters,schools,officebuildings,auditoriumsandpublictransportation.Byavoidingcrowdsduringpeakfluseason,youreduceyourchancesofinfection. Alsoavoidanyonewhoissick.Andifyou'resick,stayhomeforatleast24hoursafteryourfeverisgonesothatyoulessenyourchanceofinfectingothers. BothCOVID-19andtheflumaybespreadingatthesametime.YourlocalhealthdepartmentandtheCDCmaysuggestotherprecautionstoreduceyourriskofCOVID-19orthefluifyouhaven'tbeenfullyvaccinated.Forexample,youmayneedtopracticesocialdistancing(physicaldistancing)andstayatleast6feet(2meters)fromothersoutsideyourhousehold.Youmayalsoneedtowearaclothfacemaskwhenindoorswithpeopleoutsideyourhouseholdandwhenoutdoorsincrowdedareas.Ifyou'refullyvaccinatedandareinanareawithahighnumberofnewCOVID-19casesinthelastweek,theCDCalsorecommendswearingamaskindoorsinpublicandoutdoorsincrowdedareasorwhenyou'reinclosecontactwithunvaccinatedpeople.MoreInformationFlushotsColdandfluviruses:Howlongcantheyliveoutsidethebody?High-dosefluvaccines:Howaretheydifferentfromotherfluvaccines? ByMayoClinicStaff RequestanAppointmentatMayoClinic Diagnosis&treatment Nov.01,2021 Print Shareon:FacebookTwitter Showreferences JamesonJL,etal.,eds.Influenza.In:Harrison'sPrinciplesofInternalMedicine.20thed.NewYork,N.Y.:TheMcGraw-HillCompanies;2018.https://accessmedicine.mhmedical.com.AccessedJuly13,2018. ZacharyKC.Treatmentofseasonalinfluenzainadults.https://www.uptodate.com/contents/search.AccessedJuly13,2018. GoldmanL,etal.,eds.Influenza.In:Goldman-CecilMedicine.25thed.Philadelphia,Pa.:SaundersElsevier;2016.https://www.clinicalkey.com.AccessedJuly13,2018. BopeET,etal.Theinfectiousdiseases.In:Conn'sCurrentTherapy2018.Philadelphia,Pa.:Elsevier;2018.https://www.clinicalkey.com.AccessedJuly13,2018. Liveattenuatedinfluenzavaccine[LAIV](Thenasalsprayfluvaccine).CentersforDiseaseControlandPrevention.https://www.cdc.gov/flu/about/qa/nasalspray.htm.AccessedJuly13,2018. Flu:Whattodoifyougetsick.CentersforDiseaseControlandPrevention.https://www.cdc.gov/flu/treatment/takingcare.htm.AccessedJuly28,2020. AskMayoExpert.Influenzavaccination.MayoClinic.2020. GrohskopfLA,etal.Preventionandcontrolofseasonalinfluenzawithvaccines:RecommendationsoftheAdvisoryCommitteeonImmunizationPractices—UnitedStates,2021-2022influenzaseason.MMWRRecommendationsandReports.2021;doi:10.15585/mmwr.rr7005a1. AskMayoExpert.Influenza.MayoClinic;2020. Peopleathighriskforflucomplications.CentersforDiseaseControlandPrevention.https://www.cdc.gov/flu/highrisk/index.htm.AccessedJuly29,2020. ToshPK(expertopinion).MayoClinic.Aug.25,2020. Preventseasonalflu.CentersforDiseaseControlandPrevention.https://www.cdc.gov/flu/prevent/index.html.AccessedJuly29,2020. Howtoprotectyourself&others.CentersforDiseaseControlandPrevention.https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html.AccessedAug.26,2021. Frequentlyaskedinfluenza(flu)questions:2021-2022season.CentersforDiseaseControlandPrevention.https://www.cdc.gov/flu/season/faq-flu-season-2021-2022.htm.AccessedAug.16,2021. CDC'sdiagnosticmultiplexassayforfluandCOVID-19andsupplies.CentersforDiseaseControlandPrevention.https://www.cdc.gov/coronavirus/2019-ncov/lab/multiplex.html.AccessedJuly30,2020. Interimpublichealthrecommendationsforfullyvaccinatedpeople.CentersforDiseaseControlandPrevention.https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated-guidance.html.AccessedAug.16,2021. Whenyou'vebeenfullyvaccinated.CentersforDiseaseControlandPrevention.https://www.cdc.gov/coronavirus/2019-ncov/vaccines/fully-vaccinated.html.AccessedAug.23,2021. Related Coldandfluviruses:Howlongcantheyliveoutsidethebody? Flushots Flu:Whentoseeadoctor? High-dosefluvaccines:Howaretheydifferentfromotherfluvaccines? 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