Aciclovir is the generic name for Zovirax, a prescription medication used to treat certain virus infections.

1. WHATIS ACICLOVIR (ZOVIRAX)?
Acicloviristhe genericname forZovirax,aprescriptionmedicationusedtotreatcertainvirusinfections.
The Food andDrug Administration(FDA) approvedaciclovirtotreatviral infectionsfromthe varicella
virusthat causeschickenpox andshingles,aswell asinfectionsfromthe virusthatcausesgenital
herpes.Sometimesdoctorsprescribeaciclovirtotreatherpesinfectionsinpeople withHIV. The drug
worksby preventingvirusesfromdividingandmultiplying.The FDA approvedaciclovirinthe 1980s.
Aciclovirisavailableasa generic,made byseveral companies,orunderthe brandname Zovirax,made
by GlaxoSmithKline andavailableintablet,capsule,andliquidform.Aciclovirisone of the oldestdrugs
usedto treatherpessimplexvirusesandremainsthe firstline of treatmentforthese infections.
However,researchshowsthataciclovirisnotas effective asitusedtobe.
A 2013 study,publishedinthe journal CurrentOpinioninInfectiousDiseases, foundthatacyclovir-
resistantherpesstrainscoulddevelopovertime.
Resistance happensinpeople withahealthyimmune systemaswell asinthose withaweakened
immune system.
Aciclovir Warnings
It’simportantto knowthat aciclovirdoesnotcure viral infections.However,itcanmake infections
shorterand lessseriousforsome people.
If you’re takingaciclovirforgenital herpes,itcanreduce the severityorpreventrecurrencesof aherpes
outbreak.
If you’re takingaciclovirtotreat chickenpox or shingles,the drugcan reduce the severityof your
infection.
It’simportantto knowthat treatmentwithaciclovirworksbestwhenyoustarttakingitas soonas
possible afterarashappears.Thismeanswithinthree daysof a shinglesrashandwithin24 hoursof a
chickenpox rash.
It’susuallynotnecessarytotreat young,healthychildrenwithchickenpox,butolderchildrenoradults
whoget chickenpox mayneedtreatment.
Drinkplentyof fluidswhentakingthismedication.Childrenyoungerthan2 shouldnottake aciclovir.
Use aciclovirwithcautionif youhave kidneydisease oranyconditionthatweaknessyourimmune
system.If youhave these conditions,youcouldbe atrisk forseriousreactionstoaciclovir.
Askyour doctorfor advice onpracticingsafe sex if youhave a genital herpesinfection.Genital herpes
spreadsthroughsexual activity,andtakingacicloviralone maynotbe enoughtopreventit.

2. Aciclovirand Pregnancy
If you’re a woman,letyourdoctor knowif you are or maybe pregnantor if you’re breastfeeding.
Researchershave notstudiedacicloviruse bypregnantwomen,sothere’snotenoughevidence tosay
that itis safe to take duringpregnancy.
Acicloviralsomaypassintobreastmilk.
AciclovirSide Effects
The most commonside effectsof aciclovirtreatmentforgenital herpesinclude nausea,vomiting,and
diarrhea.
Shinglesrequirestreatmentwithhigherdosesof aciclovir,andthe mostcommonside effectsathigher
dosesare tirednessandmalaise.
Tell yourdoctor if youhave any side effects.Sideeffectsthatmaybe seeninall people usingaciclovir
include:
 Nausea
 Diarrhea
 Vomiting
 Headache
 Dizziness
 Tiredness
 Muscle or jointaches
 Visual changes
 Fluidretention
 Hair loss
 Confusion
 Changesinbehavior
Seriousside effects alsocanoccur. If you have anyof these side effects,call yourdoctorrightaway:
Severe rash,hives,ora rashthat causesblistersandpeeling
 Yellowingof skinoreyes
 Unusual bleedingorbruising
 Seizure
 Loss of consciousness
 Swellingof face,lips, ortongue

3.  Difficultybreathing
 Decreasedurine outputorbloodinthe urine
 Extreme sleepinessorconfusion
 Hallucinations
 Tingling,numbness,orshakiness
Age matters,too.People olderthan65 may have more side effectsfromaciclovirbecause theirkidneys
do notget ridof the drug as quicklyasyoungerpeople’sdo.
Aciclovir Interactions
Some drugsmay affectthe wayaciclovirworks,andaciclovirmayaffectotherdrugs youare taking.
It’sveryimportantto letyourdoctor know aboutall drugs youare taking,includinganyover-the-
counterherbsor supplements.
Drugs that mayinteractwithaciclovirinclude:
Several medicationsusedtotreatbacterial orfungal infections,includingamphotericinB
(Fungizone)andseveralantibioticssuchasamikacin(Amikin),gentamicin(Garamycin),kanamycin
(Kantrex) andtobramycin(Tobi,Nebcin)
Over-the-counterpainrelievers(Advil,Motrin,Aleve)
MedicationsusedtotreatHIV/AIDS,suchas zidovudine(Retrovir,AZT)
OtherAciclovirInteractions
You do notneedto change yourdietor your activitieswhileonaciclovir.
However,drinkplentyof fluidswhentakingthismedication.
AciclovirDosage
Your dose of aciclovirwill dependonwhyyou’re takingit.
Aciclovircomesintablets,capsules,andliquidform.Youcan take itwithor withoutfood.
Lowerdosesmaybe bestforelderlypeople andforanyone withkidneydisease.

4. Common dosagesare:
For treatmentof shingles:800milligrams(mg) fivetimesdailyfor7 to 10 days
For genital herpestreatment:200 mg five timesdailyfor10days
For preventingarecurrence of genital herpes:400 mg every12 hours for12 months
For treatingchickenpox inadultsandchildrenwhoweighmore than40 pounds:800 mg four timesdaily
for 5 days
AciclovirOverdose
An overdose of aciclovircancause kidneydamage.
Symptomsof an overdose mayinclude:
 Agitation
 Extreme sleepiness
 Loss of consciousness
 Seizures
 Kidneyfailure(nourine production)
 MissedDose of Aciclovir
You shouldtake aciclovirexactlyasdirectedbyyourdoctor.Also,donotstop takingaciclovironyour
own.
Skippingdosesorstoppingtoosoonmaynot completelytreatyourinfection,oritcouldmake the
infectionhardertotreat.
If you missa dose of aciclovir,take the misseddose assoonas youremember
If it’salmosttime for yournextdose,skipthe misseddose.
Do not double yourdose tomake up fora misseddose.
How to store aciclovir
Keepall medicinesoutof the reachand sightof children.
Store in a cool,dry place,awayfromdirectheatand light.
Can aciclovir cause problems?
Alongwiththeiruseful effects,mostmedicinescancause unwantedside-effectsalthoughnoteveryone
experiencesthem.The table belowcontainssome of the more commononesassociatedwithaciclovir.

5. The bestplace to finda full listof the side-effectswhichcanbe associatedwithyourmedicine,isfrom
the manufacturer’sprintedinformationleafletsuppliedwiththe medicine.Alternatively,youcanfindan
example of amanufacturer’sinformationleafletinthe reference sectionbelow.Speakwithyourdoctor
or pharmacistif any of the followingcontinueorbecome troublesome.
Q & A
Q: Can you please tell me if there are any long-termside effectsto taking 800mg ofaciclovir each day?
Can this cause liver,kidney,or heart damage?
A: The most commonadverse reactionsassociatedwithaciclovirkenorallyinclude malaise (generalized
discomfort),headaches,nausea,vomitinganddiarrhea.aciclovirusedtopicallyhasthe followingasthe
mostcommon adverse reactions:mildpain,burningorstingingandpruritus(itching).Therehave been
rare (lessthan1 percentof studiedpatients) thathave hadsuspectedeffectsonvariousorgansystems
such as liver,kidneys,heart,etc.Asalways,talkwithyourhealthcare providerregardingquestionsyou
have aboutside effectsof yourprescriptionmedications.JenMarsico,RPh
Q: Can Aciclovircause uncontrollable muscle twitching?
Aciclovir(Zovirax)aciclovirisamedicationusedtotreatviral infections.The mostcommonside effects
associatedwiththe oral formof Aciclovirare diarrhea,nausea,vomiting,headache,andfeelingtired
(malaise).Aciclovircreamandointmentcancause skinirritation.A searchof the prescribinginformation
for Aciclovirdidnotspecificallylistuncontrollablemuscle twitchingasa side effect.Tell yourhealth-care
provideraboutanynegative side effectsfromprescriptiondrugs.Youcan alsoreportthemto the U.S.
Foodand Drug Administrationbyvisitingwww.fda.gov/medwatchorby calling1-800-FDA-1088. For
more specificinformation,consultwithyourdoctoror pharmacistforguidance basedonyour health
statusand current medications,particularlybefore takinganyaction.Lori Mendoza,PharmD
Q: What is aciclovir?
A: Aciclovir(Zovirax) isan antiviral medicationindicatedforthe acute treatmentof herpeszoster
(shingles),the treatmentof initial episodesandthe managementof recurrentepisodesof genitalherpes
and the treatmentof chickenpox.Aciclovirisonlyapproved,bythe U.S.Food andDrug Administration
(FDA),forthe treatmentof chickenpox inthe pediatricpopulation2yearof age and older.The safety

6. and effectivenessof oral aciclovirinthe pediatricpopulation,youngerthan2 yearsof age,has not been
established.The dosage andadministrationof oral aciclovirdependsuponthe indicationforuse andage
of the patient.Aciclovircanbe administeredwithorwithoutfood.Acicloviristhe genericequivalentof
Zovirax andis currentlyavailable,fororal administration,incapsule andtabletformandas a suspension
for patientswhohave difficultyswallowingpills.Treatmentwithaciclovirshouldbe initiatedassoonas
possible afterthe firstappearance of symptoms,suchastingling,burningorblisters.Patientsbeing
treatedwithaciclovirare advisedtostayadequatelyhydratedandtake eachdose witha full glassof
waterto protectthe kidneys.The mostfrequentlyreportedadverse reactionsdifferedamongclinical
trialsof aciclovirdependingonthe indicationforuse. Duringclinicaltrialsof treatmentwithaciclovir,
the most frequentlyreportedadverse reactionsincludednausea,vomiting,diarrhea,malaiseand
headache.Forthe treatmentof shingles,thereisnoinformationregardinginitiationof treatmentmore
than 72 hoursfollowingthe onsetof rash.Patientsshouldinitiatetreatmentassoonas possible after
diagnosis.Forthe treatmentof chickenpox,informationgatheredduringclinicalstudiesreflects
initiationof treatmentwithin24 hoursfollowingrash.There isnoinformationavailable regardingthe
effectivenessof treatmentinitiatedafter24 hours.Patientsshouldbe advisedthataciclovirisnota cure
for genital herpesandthere isnoavailable researchregardingwhetheraciclovirwill preventthe
transmissionof the virustootherindividuals.
Q: What are the side effectsofaciclovir?
A: The most frequentlyreportedside effectsof aciclovir(Zovirax),fororal administration,differedin
clinical trialsdependingonthe indicationforuse.Duringclinicaltrialsof treatmentof genital herpes,
withshort-termadministrationof aciclovir,the mostfrequentlyreportedadverse reactionsincluded
nauseaand/orvomiting.Duringclinical trialsof treatmentwithlong-termadministrationwithaciclovir
for genital herpes,there were twomethodsof administrationevaluated.Intrialsevaluatingcontinuous
administrationtopreventrecurrences,the mostfrequentlyreportedadversereactionsincludednausea
and diarrheaandin those evaluatingintermittent treatmentof recurrencesoverone yeardiarrhea,
nauseaand headache were reported.The mostfrequentlyreportedadversereactionduringclinical
trialsof shingleswasmalaise.Lastly,duringclinical trialsof treatmentof chickenpox withaciclovir,the
mostfrequentlyreportedadversereactionwasdiarrhea.More seriousside effectsof aciclovirare
possible withtreatment.Kidneyfailure,insome casescausingdeath,hasbeenreportedwithaciclovir
treatment.Patientsare advisedtomaintainadequate hydrationanddrinkplentyof waterwhile taking
aciclovirtokeepthe kidneysworkingproperly.There isalsoawarningregardingthrombotic
thrombocytopenicpurpura/hemolyticuremicsyndrome (TTP/HUS),whichhasoccurredin
immunocompromisedpatientsadministeredaciclovir.Patientsshouldbe advisedtocontacttheirhealth
care providerimmediatelyif theyexperience symptomswhichmayindicatethe occurrence of more
seriousside effectsof aciclovir.Symptomsmayincludepainthe lowerback,urinatinglessthanusual or
not urinatingatall,easybruisingorbleeding,andunusual weakness.Patientsare instructedtoconsult

7. withtheirhealthcare providerif theyexperience anyotherunusual,severeortroublesomeside effects
while beingtreatedwithaciclovir.
Q: Is there an aciclovir ointment?
A: There isan aciclovir(Zovirax) ointmentformulation,availablein5% strength.Currently,aciclovir
ointmentisonlyavailable asthe brand-name Zovirax Ointment5%.Aciclovirointmentisindicatedfor
the managementof initial genital herpesandinlimitednon-life threateningmucocutaneousherpes
simplex virusinfectionsinimmunocompromisedpatients.Aciclovirointmentisnotindicatedforthe
preventionof viral transmissiontootherindividuals.Aciclovirointmentisalsonotindicatedforthe
preventionof recurrentherpesinfections.Aciclovirointmentisaprescriptionointmentthatisapplied
directlytogenital herpeslesionsandmaylessenthe durationof the symptoms associatedwithaninitial
outbreak.Forthe managementof genital herpes,patientsshouldbe instructedregardingappropriate
dosage and administrationof aciclovirointment.Patientsshouldbe advisedtoapplyasufficient
quantityof aciclovirointment toadequatelycoverall lesionsandapplyevery3hours,6 timesdaily,for7
daysof treatment.The dose size of aciclovirointmentforeachapplicationmayvarydependingonthe
size of the lesionarea.However,the dose size shouldbe approximately½ inchribbonof aciclovir
ointmentper4 square inchesof surface area,accordingto the prescribinginformation.Patientsshould
be advisedtoweara rubberglove orfingercotwhenapplyingaciclovirointmenttothe affectedareato
avoidspreadingthe virus.Aciclovirointmentshouldbe appliedasearlyaspossible afterthe
developmentof signsandsymptoms.Duringcontrolledclinical trials,mildpain,includingtemporary
burningandstinging,wasreportedinapproximately30% of patientswithnosignificantdifference
betweenpatientsreceivingZovirax ointmentandpatientsreceivingplacebo.Local prurituswasalso
reportedin4% of patients.Aciclovirointment5% shouldbe usedexactlyasprescribedbyahealthcare
provider.Patientsshouldbe advisednottoexceedthe recommendeddosage,frequencyof applications
and lengthof treatment.
Q: How longis aciclovir treatment?
A: Howlongaciclovir(Zovirax) treatmentisintendedfordependsuponthe indicationforuse.Acicloviris
a prescriptionantiviral agentapproved,bythe U.S.FoodandDrug Administration(FDA),forthe acute
treatmentof herpeszoster(shingles),the treatmentof initial episodesandthe managementof
recurrentepisodesof genital herpesandthe treatmentof chickenpox.Aciclovirtreatmentisapproved
for all indicationsforadultsandforthe treatmentof chickenpox inchildren2yearof age andolder.For
the acute treatmentof shingles,the lengthof aciclovirtreatmentis7to 10 days.The usual
recommendedadultdosage is800 mg administeredevery4hours,5 timesdaily.Forthe treatmentof

8. initial episodesof genital herpes,the lengthof aciclovirtreatmentis10 days.The usual recommended
adultdosage is200 mg administeredevery4hours,5 timesdaily.Forthe managementof recurrent
episodesof genitalherpes,there weretwomethodsof administrationof aciclovirtreatmentevaluated
inclinical trials.Forintermittenttherapy,the lengthof aciclovirtreatmentis5 days.Treatmentshould
be initiatedatthe earliestsignorsymptomof recurrence,knownasa prodrome.The usual adultdosage
is200 mg administeredevery4hours,5 timesdaily.The otheroptionischronicsuppressive therapyin
whichaciclovirtreatmentisusedforupto 12 monthsand followedbyre-evaluationbyahealthcare
providertoassessthe needforcontinuedtreatment.The usual adultdosage is400 mg twice daily.
Alternativedosagesmayrange from200 mg 3 timesdailyto200 mg 5 timesdaily,accordingtothe
prescribinginformationforZovirax, the brand-name of aciclovir.Forthe treatmentof chickenpoxfor
adultsand children,the recommendedlengthof aciclovirtreatmentis5 days.Whentreatmentis
required,itshouldbe initiatedatthe earliestsignorsymptomof chickenpox.The effectivenessof
treatmentinitiatedafter24 hoursfollowingthe onsetof symptomsisunknown.The usual dosage for
adultsand childrenweighingover40 kg is800 mg administered4timesdaily.The usual dosage for
children2 yearsof age and olderis20 mg/kgper dose administered4timesdaily.
Q: Does aciclovir cause hair loss?
A: Duringpostmarketingexperience,observedinclinical practice,aciclovir(Zovirax)wasreportedto
cause hair loss.However,becauseadverse reactionsreportedinclinical practice, andnotduring
controlledclinicaltrials,are reportedvoluntarilyfromanunknownpopulationsize,the frequencyof the
adverse reactionisunknown.Otheradversereactionsreportedduringpostmarketingexperience with
aciclovirincludedheadache,allergicreaction,fever,pain,swellinginthe extremities,agitation,
confusion,dizziness,somnolence,tremors,diarrhea,gastrointestinal distress,nausea,anemia,
leucopenia,thrombocytopenia,elevatedliverenzymes,hepatitis,jaundice,myalgia,prutitus,rash,visual
disturbances,kidneyfailure,kidneypain,elevatedbloodureanitrogen(BUN) andcreatinine,and
hematuria.Accordingtothe prescribinginformationforZovirax,the brand-nameof aciclovir,the most
frequentlyreportedadverse reactionsreportedduringclinical trialsincludednausea,vomiting,diarrhea,
malaise andheadache andvarieddependingonthe indicationfortreatment.Patientsare instructedto
contact theirhealthcare provider,immediately,if theyexperience symptomswhichmay indicate more
seriousadverse reactionsof aciclovirhave developed.Symptomsmayinclude painthe lowerback,
urinatinglessthanusual ornot urinatingatall,easybruisingorbleeding,andunusual weakness.Itis
importantforpatientstoreportany unusual or bothersome reactionstheyexperience while being
treatedwithaciclovir.Aciclovirshouldbe takenexactlyasprescribed.

9. Q: Are there any aciclovir interactionswith othermedications?
A: There are not manyaciclovir(Zovirax) interactionswithothermedications.If aciclovirinteractswith
certainothermedications,the effectscanbe increased,decreasedoraltered.One aciclovirinteraction
possible iswiththe medicationprobenecid(Benemid).Itisespeciallyimportantforpatientstaking
probenecidtoconsultwithahealthcare providerpriorto treatmentwithaciclovir.If youare currently
takingprobenecid,youmaynotbe able to take aciclovir,oryoumay require dosage adjustmentsof
special testsduringtreatment.Some of the otherpossibleaciclovirinteractionswithothermedications
may include Demerol(meperidine),Dilantin(phenytoin),Cellcept(mycophenolatemofetil),Viread
(tenofovir),Zanaflex(tizanidine),Depakene (valproicacid),Retrovir(zidovudine),theophyllinesandthe
varicellavirusvaccine.Itisessential forpatientstoconsultwiththeirhealthcare providerregardingall
prescriptionandoverthe countermedicationstheytake priortoinitiationof treatmentwithaciclovirto
avoidpotentiallydangerousdruginteractions.Thisincludesall vitamins,minerals,herbalsupplements
and anydrugs prescribedbyanotherdoctor.
Q: Does aciclovir cause stomach pain?
A: Duringclinical trials,patientsdidnotreportaciclovir(Zovirax) causingstomachpain.However,most
of the frequentlyreportedadverse reactionsassociatedwithaciclovirtreatmentwere relatedtothe
gastrointestinal system.Accordingtothe prescribinginformationforZovirax,the brand-name
equivalentof aciclovir,the mostfrequentlyreportedgastrointestinal adverse reactionsreportedby
patientsduringclinical trialsforanyindicationincludednausea,vomitinganddiarrhea.Inaddition,post
marketingexperience revealedothergastrointestinalrelatedadverse reactionsobservedinclinical
practice.In clinical practice experience withaciclovir,patientsreportedexperiencingdiarrhea,
gastrointestinal distressandnausea.There wasnofurtherdescriptionregardinggastrointestinal distress
and whetherornot patientsexperiencedstomachpainspecifically.Othercommonadverse reactions
possible withaciclovirtreatmentinclude headacheandmalaise.Itisessential forpatientstoconsulta
healthcare providerif theyexperienceanyunusual orbothersome adverse reactionswhile being
treatedwithaciclovirforfurtherevaluation.Aciclovirisanantiviral medicationavailable byprescription
only.Aciclovirisindicatedforthe acute treatmentof shingles,the treatmentof initial episodesandthe
managementof recurrentepisodesof genitalherpesandthe treatmentof chickenpox.Acicloviris
approvedforuse inadultsfor all indicationsandforthe treatmentof chickenpox inthe pediatric
populationinchildren2yearsof age and older.Aciclovirmaybe taken withoutregardtofoodand
shouldbe takenexactlyasinstructedbya healthcare provider.