SAVE 30% ON EACH EBOOK AND 60% ON THE COMPLETE BUNDLE!
Valacyclovir vs Acyclovir for Genital Herpes
Compare valacyclovir and acyclovir for genital herpes, including effectiveness, dosing frequency, episodic vs suppressive use, safety and cost.
MEDICAL & WELLNESS
Brandon Hart
1/14/20264 min read
Valacyclovir vs acyclovir: the quick comparison
Valacyclovir and acyclovir are closely related prescription antivirals used to treat and suppress genital herpes. In the UK, acyclovir is usually written as aciclovir. Valacyclovir is converted into acyclovir in the body and is absorbed more efficiently, so it can usually be taken less often.
CDC guidance says acyclovir, valacyclovir and famciclovir appear equally effective for episodic treatment of recurrent genital herpes. The practical difference is usually dosing frequency, convenience, availability and cost rather than one drug being universally stronger.
Valacyclovir: usually fewer daily doses, which some people find easier to follow.
Acyclovir: usually more frequent dosing and may cost less in some private settings.
Both: can treat a first episode, shorten recurrent episodes or be used as daily suppressive therapy when prescribed appropriately.
Neither medicine removes HSV from the body or guarantees that transmission cannot occur.
How the medicines work
Both medicines interfere with HSV replication. Valacyclovir is a prodrug, meaning the body converts it into acyclovir after absorption. Its improved absorption allows less frequent dosing in many treatment plans.
Oral antiviral treatment can partially control symptoms and recurrences, but it does not eradicate latent virus. When treatment stops, it does not permanently change the future risk, frequency or severity of recurrences.
What are episodic and suppressive treatment?
Episodic treatment
Episodic treatment is taken for a limited period when an outbreak starts. CDC guidance says it works best when started during the warning sensations before lesions appear or within one day of lesion onset. A clinician may provide a prescription in advance so treatment can begin promptly.
Suppressive treatment
Suppressive treatment is taken every day to reduce recurrences. CDC guidance reports that suppressive therapy reduces recurrence frequency by about 70–80% among people who have frequent outbreaks, and it can also help people with less frequent recurrences. Treatment choices should be reviewed with a clinician as recurrence frequency can change over time.
Daily valacyclovir has evidence for reducing HSV-2 transmission in certain couples when combined with condoms and avoiding sex during outbreaks. It lowers risk but does not remove it. Read more in our HSV transmission guide.
Example genital-herpes regimens in CDC guidance
These are examples from CDC clinical guidance, not personalised prescribing instructions. The correct medicine, dose and duration depend on whether this is a first episode or recurrence, whether treatment is episodic or suppressive, kidney function, immune status, pregnancy and other medicines. Follow your own prescription.
First clinical episode
Acyclovir: 400 mg by mouth three times daily for 7–10 days.
Valacyclovir: 1 g by mouth twice daily for 7–10 days.
CDC guidance recommends antiviral treatment for every first clinical episode. Treatment may be extended by a clinician if healing is incomplete after 10 days.
Recurrent HSV-2: episodic treatment
Acyclovir: CDC lists more than one regimen, including 800 mg twice daily for 5 days or 800 mg three times daily for 2 days.
Valacyclovir: CDC lists 500 mg twice daily for 3 days or 1 g once daily for 5 days.
Recurrent HSV-2: daily suppression
Acyclovir: 400 mg twice daily.
Valacyclovir: 500 mg or 1 g once daily. CDC notes that 500 mg once daily may be less effective for people with ten or more outbreaks a year.
Guidelines and licensed regimens can differ between countries and patient groups. Do not start, stop, switch or change a dose without a qualified prescriber.
Which option may be more practical?
Valacyclovir may suit you when
Fewer daily doses would make it easier to follow the prescription.
You travel or have an irregular routine.
Your prescriber recommends it for suppression or transmission reduction.
Acyclovir may suit you when
It is more readily available or affordable through your provider.
You are comfortable with more frequent dosing.
Your clinician has experience using it for your circumstances.
Do not assume one option will always be cheaper. NHS prescription arrangements, exemptions, insurance and private-pharmacy prices vary and change. Compare the full prescribed course through a registered pharmacy rather than relying on an old online price.
Side effects and safety
Both medicines are generally well tolerated, but side effects can occur. Headache, nausea, stomach discomfort and dizziness are reported with these medicines. Read the patient leaflet supplied with your exact product.
Acyclovir is cleared mainly through the kidneys. Valacyclovir becomes acyclovir in the body, so kidney function matters for both medicines. Dose adjustment may be needed for reduced kidney function. Older adults, people who are dehydrated and people taking medicines that can affect the kidneys may need additional care.
Tell the prescriber about kidney problems, pregnancy, breastfeeding, immune suppression and all other medicines. Seek urgent medical help for severe confusion, hallucinations, seizures, very little urine, facial or throat swelling, breathing difficulty or a severe rash.
Can antivirals prevent transmission?
Suppressive therapy can reduce viral shedding and transmission risk, but no antiviral makes sex risk-free. Continue to avoid sex during warning symptoms or active sores, consider condoms and discuss HSV status with partners. The evidence for transmission reduction is specific to particular study populations, so a clinician can explain how closely it applies to your situation.
Common questions
Is valacyclovir stronger than acyclovir?
It is absorbed more efficiently, but that does not mean it always produces a better clinical result. When each drug is prescribed in an appropriate regimen, CDC guidance describes them as similarly effective for episodic recurrent genital herpes.
Can I switch between them?
A prescriber can switch medicines when appropriate, but the dose and schedule are not interchangeable. Do not convert a dose yourself.
Do I need daily treatment forever?
Not necessarily. Some people use treatment only for outbreaks, while others prefer daily suppression. CDC guidance recommends discussing continued suppressive therapy with a clinician periodically because recurrence frequency may decrease over time.
What should I do if I miss a dose?
Follow the patient leaflet and advice from your pharmacist. Do not take two doses together unless a healthcare professional specifically tells you to.
Do natural supplements work as well?
No supplement has evidence equivalent to prescription antivirals for treating genital herpes. Tell your clinician about supplements because they can still cause side effects or interact with medicines.
Questions to discuss with a clinician
Is this a first episode, a recurrence or a reason to consider daily suppression?
How quickly can I begin episodic treatment when symptoms start?
Would fewer daily doses improve adherence?
Does my kidney function or another medicine require a different dose?
What is the current total cost through the NHS, insurance or a registered pharmacy?
How often should we review whether suppression is still useful?
For help recognising an outbreak, see genital herpes symptoms in men.
Primary sources and guidance
Last reviewed: 21 September 2026. Written by Brandon Hart. This article has not been medically reviewed and is for general education, not diagnosis or personalised prescribing advice.
MODERN HSV PLAYBOOK
THE SERIES
© 2026 Modern HSV Playbook. All rights reserved.
SITE
Content for informational purposes only. Not a substitute for professional medical advice.