Table of ContentsView AllTable of ContentsUnderstanding Herpes VirusesWhat Is Valacyclovir?What Is Acyclovir?Dosage ComparisonComparative EfficacyAlternative Treatment OptionsSide EffectsInteractionsFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Understanding Herpes Viruses
What Is Valacyclovir?
What Is Acyclovir?
Dosage Comparison
Comparative Efficacy
Alternative Treatment Options
Side Effects
Interactions
Frequently Asked Questions
Valacyclovir and acyclovir work to lessen pain and expedite the healing of sores or blisters in people withchickenpox,shingles(also known asherpes zoster),genital herpes(in adults), andcold sores(also known as herpes labialis).
However, while primarily similar, some significant differences exist between valacyclovir and acyclovir, including dosing guidelines, Food and Drug Administration (FDA)-approved uses, brand-name affiliations, and slightly different side effects.
To explain these similarities and differences and discuss other pertinent information related to their safe and effective use, this article will provide an in-depth comparison of valacyclovir and acyclovir.
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The virus that most commonly causes cold sores,herpes simplex virus 1 (HSV-1), is a prevalentsexually transmitted infection (STI), that has affected 67% of the world’s population. HSV-1 is commonly referred to as oral herpes.
Oral herpes tends to affect your mouth or face and causes cold sores. It spreads through contact with saliva.
In comparison, the other type of herpes,herpes simplex virus 2 (HSV-2), is also highly prevalent.
HSV-2 causes genital herpes, infecting nearly 13% of the world’s population. HSV-2 causes sores on the skin following physical contact with the genitals of an infected person. Herpes sores typically last a week to 10 days.
Similar to HSV-1 and HSV-2 is thevaricella-zoster virus (VZV), the herpes virus that causes chickenpox and shingles. VZV is spread via physical contact; once infected, the virus lives dormant in the body forever.
Chickenpox is infectious one to two days before the rash starts and until the blisters have dried and scabbed over.
Valacyclovir is an orally administered medication that is taken as a swallowable tablet.
It is sold under the brand-name form Valtrex, which contains valacyclovir as its active ingredient. Valtrex is generally safe for most people and carries noboxed warning.
Valtrex’s (valacyclovir) FDA-approved uses in adults 18 and older include the treatment of:
Valtrex’s (valacyclovir) FDA-approved uses in children and adolescents include the treatment of:
There are some off-label uses (non-FDA-approved) for valacyclovir. Some examples may include times when herpes simplex virus causes skin symptoms, such as sores or blistering in various body areas.
As a result, valacyclovir has been used in the treatment ofherpetic whitlow(herpes virus that causes blisters on the skin near fingernails) andherpes gladiatorum(a form of herpes most commonly spread via athletic events involving skin-to-skin contact).
How Does Valacyclovir Work?
Valacyclovir is a prodrug of acyclovir. This means that during consumption, your liver slightly alters the chemical structure of valacyclovir after you swallow it to change it into acyclovir.
Acyclovir is sold in various dosage forms, including oral tablets and capsules, an oral suspension, creams, ointment, and even an injectable, subcutaneous (under the skin) form.
Like valacyclovir, acyclovir is generally safe for most people and carries no boxed warning.
Additionally, branded versions of acyclovir are also on the market. One such example is Zovirax, which is available as an ointment or cream.
Acyclovir’s FDA-approved uses in adults include:
In comparison, acyclovir’s FDA-approved uses in children and adolescents include:
How Does Acyclovir Work?
Acyclovir works the same way as valacyclovir once it is converted to the active form of the drug. It inserts itself into the DNA chain of the herpes virus and inhibits further growth.
This stops the ability of the virus to keep producing more copies of itself.
The following will outline standard dosing recommendations for valacyclovir vs. acyclovir concerning age, weight, indication, and mode of administration:
How Fast Do They Work?
You can expect acyclovir and valacyclovir to help cold sores within two to three days and genital herpes in around five days. However, blisters and rashes may take up to a couple of weeks to clear completely.
The sooner you can start taking acyclovir or valacyclovir once symptoms show up, the better the medications will work to treat the outbreak.
It’s also essential to take them exactly as prescribed, several times daily. It may help to set a reminder on your phone so as not to miss doses and potentially reduce the effectiveness of the antiviral.
While there exist little head-to-head comparisons of these drugs, one study that featured over 1,000 adult participants showed that valacyclovir helped resolve shingles symptoms faster than acyclovir, with valacyclovir resolving symptoms of shingles in 38 days versus acyclovir’s 51 days.
Valacyclovir remains in your system longer than acyclovir, so some people can make it more accessible.
Both drugs work very similarly; generally, one is not recommended over the other.
For example,over-the-counter (OTC) cold sore treatmentoptions exist, such as Abreva (docosanol), Orajel (benzocaine), and Herpecin L (dimethicone/meradimate/octinoxate/octisalate/oxybenzone).
These creams or ointments are applied directly to the cold sore to lessen pain or help treat the sore. Applying these at the first sign of a cold sore is best.
You can also place ice on the cold sore or suck on ice chips to help numb the area. Avoiding certain foods such as tomatoes, citrus fruits, and spicy foods may help prevent the burning if these foods touch a cold sore.
Finally, apply petroleum jelly or another hydrating ointment to the sores and surrounding area to prevent dry and cracked skin.
Side Effects & Precautions
The most common side effects of acyclovir and valacyclovir are mild and usually resolve independently.
However, recorded side effects associated with the use of both drugs have been symptoms of nausea, vomiting, headache, and diarrhea.
Precautions
Although rare, serious side effects are possible with valacyclovir and acyclovir, especially in certain circumstances, including the following:
If you have a weakened immune system, such as in advancedhuman immunodeficiency virus (HIV), or if you are atransplant recipient, you may be at higher risk of two conditions calledhemolytic uremic syndrome(HUS, when kidney function diminishes due toEscherichiacoli[E.coli] infection) andthrombotic thrombocytopenic purpura(TTP, a blood clotting disorder that can damage the kidneys).
Potential for Interaction
Valacyclovir and acyclovir don’t have any known significant interactions with other medications.
However, giving your healthcare provider and pharmacist your current medication list is still essential to check for potential issues.
For example, other medications that cause kidney damage may increase the risk of kidney issues from taking valacyclovir or acyclovir.
Summary
Acyclovir and valacyclovir are both effective antiviral medications that can shorten the time until symptoms you’re experiencing from shingles, genital herpes, or cold sores improve.
Valacyclovir may be simpler for you to take due to its more straightforwarddosing schedule, and it also resolved shingles symptoms faster than acyclovir in one study.
Remember that both medications will work better if you start taking them at the first sign of symptoms, such as burning, tingling, or itching.
Your healthcare provider will consider your preferences and other factors to determine your best choice.
Frequently Asked QuestionsValacyclovir and acyclovir tablets should be stored at room temperature (between 68 and 77 degrees F) in a well-closed container away from excess heat or moisture.Store liquid forms of the medicines in the fridge (between 36 and 46 degrees F) and throw away any remaining liquid after 28 days.Keep all acyclovir and valacyclovir out of reach of children.Yes, if you have genital herpes, you are still contagious while taking valacyclovir or acyclovir. Remember, these drugs reduce the risk of virus transmission but do not eliminate the risk.As a result, you should use protection, including condoms, during sexual intercourse.
Valacyclovir and acyclovir tablets should be stored at room temperature (between 68 and 77 degrees F) in a well-closed container away from excess heat or moisture.Store liquid forms of the medicines in the fridge (between 36 and 46 degrees F) and throw away any remaining liquid after 28 days.Keep all acyclovir and valacyclovir out of reach of children.
Valacyclovir and acyclovir tablets should be stored at room temperature (between 68 and 77 degrees F) in a well-closed container away from excess heat or moisture.
Store liquid forms of the medicines in the fridge (between 36 and 46 degrees F) and throw away any remaining liquid after 28 days.
Keep all acyclovir and valacyclovir out of reach of children.
Yes, if you have genital herpes, you are still contagious while taking valacyclovir or acyclovir. Remember, these drugs reduce the risk of virus transmission but do not eliminate the risk.As a result, you should use protection, including condoms, during sexual intercourse.
Yes, if you have genital herpes, you are still contagious while taking valacyclovir or acyclovir. Remember, these drugs reduce the risk of virus transmission but do not eliminate the risk.
As a result, you should use protection, including condoms, during sexual intercourse.
22 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Valacyclovir.MedlinePlus.Acyclovir.Zhu S, Viejo-Borbolla A.Pathogenesis and virulence of herpes simplex virus.Virulence. 2021;12(1):2670-2702. doi:10.1080/21505594.2021.1982373World Health Organization.Herpes simple virus.MedlinePlus.Chickenpox.DailyMed.Label: Valtrex- valacyclovir hydrochloride tablet, film coated.Staikuniene J, Staneviciute J.Long-term valacyclovir treatment and immune modulation for Herpes-associated erythema multiforme.Cent Eur J Immunol. 2015;40(3):387-390. doi:10.5114/ceji.2015.54604Schuster AK, Harder BC, Schlichtenbrede FC, Jarczok MN, Tesarz J.Valacyclovir versus acyclovir for the treatment of herpes zoster ophthalmicus in immunocompetent patients.Cochrane Database Syst Rev. 2016;11(11):CD011503. doi:10.1002/14651858.CD011503.pub2MedlinePlus.Acyclovir injection.DailyMed.Label: Zovirax- acyclovir ointment.DailyMed.Label: Zovirax- acyclovir cream.DailyMed.Label: Sitavig- acyclovir tablet, delayed release.DailyMed.Label: acyclovir- acyclovir tablet.Mayer CS, Blobner K, Storr J, Baur ID, Khoramnia R.Acute retinal necrosis: signs, treatment, complications and outcome.Diagnostics (Basel). 2022;12(2):386. doi:10.3390/diagnostics12020386Bodilsen J, Tattevin P, Tong SYC, Naucler P, Nielsen H.Treatment of herpes simplex virus type 2 meningitis: a survey among infectious diseases specialists in France, Sweden, Australia, and Denmark.Open Forum Infect Dis. 2022;9(12):ofac644. doi:10.1093/ofid/ofac644Bell DJ, Suckling R, Rothburn MM, et al.Management of suspected herpes simplex virus encephalitis in adults in a U.K. teaching hospital.Clin Med (Lond). 2009;9(3):231-235. doi:10.7861/clinmedicine.9-3-231Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ.Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults.Antimicrob Agents Chemother. 1995;39(7):1546-1553. doi:10.1128/AAC.39.7.1546DailyMed.Label: Abreva- docosanol cream.DailyMed.Label: Orajel 3X Medication for All Mouth Sores- benzocaine, menthol, zinc chloride gel.DailyMed.Label: Herpecin L- dimethicone and meradimate and octinoxate and octisalate and oxybenzone stick.Purnamawati S, Indrastuti N, Danarti R, Saefudin T.The role of moisturizers in addressing various kinds of dermatitis: a review.Clin Med Res. 2017;15(3-4):75-87. doi:10.3121/cmr.2017.1363Bonnar PE.Suppressive valacyclovir therapy to reduce genital herpes transmission: good public health policy?Mcgill J Med. 2009;12(1):39-46.
22 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.MedlinePlus.Valacyclovir.MedlinePlus.Acyclovir.Zhu S, Viejo-Borbolla A.Pathogenesis and virulence of herpes simplex virus.Virulence. 2021;12(1):2670-2702. doi:10.1080/21505594.2021.1982373World Health Organization.Herpes simple virus.MedlinePlus.Chickenpox.DailyMed.Label: Valtrex- valacyclovir hydrochloride tablet, film coated.Staikuniene J, Staneviciute J.Long-term valacyclovir treatment and immune modulation for Herpes-associated erythema multiforme.Cent Eur J Immunol. 2015;40(3):387-390. doi:10.5114/ceji.2015.54604Schuster AK, Harder BC, Schlichtenbrede FC, Jarczok MN, Tesarz J.Valacyclovir versus acyclovir for the treatment of herpes zoster ophthalmicus in immunocompetent patients.Cochrane Database Syst Rev. 2016;11(11):CD011503. doi:10.1002/14651858.CD011503.pub2MedlinePlus.Acyclovir injection.DailyMed.Label: Zovirax- acyclovir ointment.DailyMed.Label: Zovirax- acyclovir cream.DailyMed.Label: Sitavig- acyclovir tablet, delayed release.DailyMed.Label: acyclovir- acyclovir tablet.Mayer CS, Blobner K, Storr J, Baur ID, Khoramnia R.Acute retinal necrosis: signs, treatment, complications and outcome.Diagnostics (Basel). 2022;12(2):386. doi:10.3390/diagnostics12020386Bodilsen J, Tattevin P, Tong SYC, Naucler P, Nielsen H.Treatment of herpes simplex virus type 2 meningitis: a survey among infectious diseases specialists in France, Sweden, Australia, and Denmark.Open Forum Infect Dis. 2022;9(12):ofac644. doi:10.1093/ofid/ofac644Bell DJ, Suckling R, Rothburn MM, et al.Management of suspected herpes simplex virus encephalitis in adults in a U.K. teaching hospital.Clin Med (Lond). 2009;9(3):231-235. doi:10.7861/clinmedicine.9-3-231Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ.Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults.Antimicrob Agents Chemother. 1995;39(7):1546-1553. doi:10.1128/AAC.39.7.1546DailyMed.Label: Abreva- docosanol cream.DailyMed.Label: Orajel 3X Medication for All Mouth Sores- benzocaine, menthol, zinc chloride gel.DailyMed.Label: Herpecin L- dimethicone and meradimate and octinoxate and octisalate and oxybenzone stick.Purnamawati S, Indrastuti N, Danarti R, Saefudin T.The role of moisturizers in addressing various kinds of dermatitis: a review.Clin Med Res. 2017;15(3-4):75-87. doi:10.3121/cmr.2017.1363Bonnar PE.Suppressive valacyclovir therapy to reduce genital herpes transmission: good public health policy?Mcgill J Med. 2009;12(1):39-46.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
MedlinePlus.Valacyclovir.MedlinePlus.Acyclovir.Zhu S, Viejo-Borbolla A.Pathogenesis and virulence of herpes simplex virus.Virulence. 2021;12(1):2670-2702. doi:10.1080/21505594.2021.1982373World Health Organization.Herpes simple virus.MedlinePlus.Chickenpox.DailyMed.Label: Valtrex- valacyclovir hydrochloride tablet, film coated.Staikuniene J, Staneviciute J.Long-term valacyclovir treatment and immune modulation for Herpes-associated erythema multiforme.Cent Eur J Immunol. 2015;40(3):387-390. doi:10.5114/ceji.2015.54604Schuster AK, Harder BC, Schlichtenbrede FC, Jarczok MN, Tesarz J.Valacyclovir versus acyclovir for the treatment of herpes zoster ophthalmicus in immunocompetent patients.Cochrane Database Syst Rev. 2016;11(11):CD011503. doi:10.1002/14651858.CD011503.pub2MedlinePlus.Acyclovir injection.DailyMed.Label: Zovirax- acyclovir ointment.DailyMed.Label: Zovirax- acyclovir cream.DailyMed.Label: Sitavig- acyclovir tablet, delayed release.DailyMed.Label: acyclovir- acyclovir tablet.Mayer CS, Blobner K, Storr J, Baur ID, Khoramnia R.Acute retinal necrosis: signs, treatment, complications and outcome.Diagnostics (Basel). 2022;12(2):386. doi:10.3390/diagnostics12020386Bodilsen J, Tattevin P, Tong SYC, Naucler P, Nielsen H.Treatment of herpes simplex virus type 2 meningitis: a survey among infectious diseases specialists in France, Sweden, Australia, and Denmark.Open Forum Infect Dis. 2022;9(12):ofac644. doi:10.1093/ofid/ofac644Bell DJ, Suckling R, Rothburn MM, et al.Management of suspected herpes simplex virus encephalitis in adults in a U.K. teaching hospital.Clin Med (Lond). 2009;9(3):231-235. doi:10.7861/clinmedicine.9-3-231Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ.Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults.Antimicrob Agents Chemother. 1995;39(7):1546-1553. doi:10.1128/AAC.39.7.1546DailyMed.Label: Abreva- docosanol cream.DailyMed.Label: Orajel 3X Medication for All Mouth Sores- benzocaine, menthol, zinc chloride gel.DailyMed.Label: Herpecin L- dimethicone and meradimate and octinoxate and octisalate and oxybenzone stick.Purnamawati S, Indrastuti N, Danarti R, Saefudin T.The role of moisturizers in addressing various kinds of dermatitis: a review.Clin Med Res. 2017;15(3-4):75-87. doi:10.3121/cmr.2017.1363Bonnar PE.Suppressive valacyclovir therapy to reduce genital herpes transmission: good public health policy?Mcgill J Med. 2009;12(1):39-46.
MedlinePlus.Valacyclovir.
MedlinePlus.Acyclovir.
Zhu S, Viejo-Borbolla A.Pathogenesis and virulence of herpes simplex virus.Virulence. 2021;12(1):2670-2702. doi:10.1080/21505594.2021.1982373
World Health Organization.Herpes simple virus.
MedlinePlus.Chickenpox.
DailyMed.Label: Valtrex- valacyclovir hydrochloride tablet, film coated.
Staikuniene J, Staneviciute J.Long-term valacyclovir treatment and immune modulation for Herpes-associated erythema multiforme.Cent Eur J Immunol. 2015;40(3):387-390. doi:10.5114/ceji.2015.54604
Schuster AK, Harder BC, Schlichtenbrede FC, Jarczok MN, Tesarz J.Valacyclovir versus acyclovir for the treatment of herpes zoster ophthalmicus in immunocompetent patients.Cochrane Database Syst Rev. 2016;11(11):CD011503. doi:10.1002/14651858.CD011503.pub2
MedlinePlus.Acyclovir injection.
DailyMed.Label: Zovirax- acyclovir ointment.
DailyMed.Label: Zovirax- acyclovir cream.
DailyMed.Label: Sitavig- acyclovir tablet, delayed release.
DailyMed.Label: acyclovir- acyclovir tablet.
Mayer CS, Blobner K, Storr J, Baur ID, Khoramnia R.Acute retinal necrosis: signs, treatment, complications and outcome.Diagnostics (Basel). 2022;12(2):386. doi:10.3390/diagnostics12020386
Bodilsen J, Tattevin P, Tong SYC, Naucler P, Nielsen H.Treatment of herpes simplex virus type 2 meningitis: a survey among infectious diseases specialists in France, Sweden, Australia, and Denmark.Open Forum Infect Dis. 2022;9(12):ofac644. doi:10.1093/ofid/ofac644
Bell DJ, Suckling R, Rothburn MM, et al.Management of suspected herpes simplex virus encephalitis in adults in a U.K. teaching hospital.Clin Med (Lond). 2009;9(3):231-235. doi:10.7861/clinmedicine.9-3-231
Beutner KR, Friedman DJ, Forszpaniak C, Andersen PL, Wood MJ.Valaciclovir compared with acyclovir for improved therapy for herpes zoster in immunocompetent adults.Antimicrob Agents Chemother. 1995;39(7):1546-1553. doi:10.1128/AAC.39.7.1546
DailyMed.Label: Abreva- docosanol cream.
DailyMed.Label: Orajel 3X Medication for All Mouth Sores- benzocaine, menthol, zinc chloride gel.
DailyMed.Label: Herpecin L- dimethicone and meradimate and octinoxate and octisalate and oxybenzone stick.
Purnamawati S, Indrastuti N, Danarti R, Saefudin T.The role of moisturizers in addressing various kinds of dermatitis: a review.Clin Med Res. 2017;15(3-4):75-87. doi:10.3121/cmr.2017.1363
Bonnar PE.Suppressive valacyclovir therapy to reduce genital herpes transmission: good public health policy?Mcgill J Med. 2009;12(1):39-46.
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