Valacyclovir vs. Acyclovir:
What's the Difference?

Written by Kathleen Morrison
Medically Reviewed by Andrea Sleeth WHNP-BC, MSCP a healthcare provider affiliated with Wisp

Key takeaways

• Acyclovir and Valacyclovir are antiviral medications used to treat infections caused by the herpes simplex virus (HSV-1 and HSV-2).
• Valacyclovir is a prodrug of Acyclovir, meaning it converts into Acyclovir in the body once absorbed. The active antiviral is the same in both cases.
• Because Valacyclovir has higher bioavailability, it is typically prescribed at fewer doses per day, while Acyclovir generally requires more frequent dosing.
• A provider can help determine which option is appropriate for you based on your history, kidney function, and dosing preferences.
• Both work by blocking the herpes virus from copying its DNA, and clinical guidelines recommend starting treatment at the first sign of symptoms may help shorten the duration of an outbreak.

So, you’ve been diagnosed with herpes (or maybe you’re just doing some proactive research - love that for you), and now you’re staring at two different meds: Acyclovir and Valacyclovir. What’s the difference? Which one should you go with? And do you really need to overthink it?

Both are prescription antivirals used to treat herpes, including cold sores and genital herpes.

Here’s the part most comparisons bury: Valacyclovir is a prodrug of Acyclovir, so once it’s absorbed, your body converts it into the same active antiviral.

The real difference between Acyclovir and Valacyclovir isn't the drug doing the work; it's how much of it your body absorbs, what each one costs, and how many times a day you want to think about it. A provider weighs all of that, plus your history, before deciding which one is appropriate for you.

Below, we’ll break down whether they’re really the same drug, how the dosing schedules actually compare, typical costs, and which questions are worth bringing to a provider.

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Are Valacyclovir and Acyclovir the same?

Short answer: not quite, but closer than you'd think.

Valacyclovir is a prodrug of Acyclovir, which is the pharmacological way of saying it's an inactive form your body has to unpack first. After you swallow it, enzymes in your intestine and liver convert Valacyclovir into Acyclovir in the body. So, either way, the antiviral fighting the herpes virus is Acyclovir.

The headline difference is absorption: Valacyclovir hydrochloride was designed so that more of each dose is converted and absorbed by the body, which is what bioavailability measures.

But absorption is just the first domino. That one design choice ripples outward into almost everything you'd actually notice at the pharmacy counter: how many times a day you're taking a pill, what a full course costs, what the tablet looks like, which conditions each one carries an FDA-labeled indication for, and how a provider weighs one against the other for your situation.

So the rest of this page works through those splits one at a time: dosing schedules for each, what they cost without insurance, side effects of Acyclovir and Valacyclovir, etc.

Acyclovir vs. Valacyclovir: The quick breakdown

The active drug

• They're the same antiviral at the finish line.
• Valacyclovir is a prodrug of Acyclovir, so your body converts it into Acyclovir after absorption.

What they're FDA-approved to treat

• Both are FDA-approved for genital herpes and shingles. Valacyclovir is also FDA-approved for cold sores; oral Acyclovir tablets are not, so using them for cold sores is considered *off-label.
• Valacyclovir alone is labeled for reducing transmission of genital herpes in immunocompetent adults with a history of nine or fewer recurrences yearly, used alongside safer sex practices. Acyclovir's label notes there are no data on whether it lowers the risk of passing herpes to a partner. The indication does not extend to Acyclovir or to suppressive therapy generally.

*This specific use of this prescription medication is not approved by the U.S. Food and Drug Administration (FDA). Such use, known as “off-label” use, may be prescribed by a licensed healthcare provider based on their clinical judgment. The safety and effectiveness of medications for off-label uses may not be established by the FDA. This information is for educational purposes only and is not medical advice. Always consult your healthcare provider regarding treatment decisions.

Dosing

• Acyclovir usually requires more frequent dosing. Labeled adult regimens run from 400 mg to 800 mg.
• Valacyclovir’s labeled adult regimens run from 500 mg to 2000 mg (for oral only outbreaks) and may require less frequent dosing.

Side effects

• Similar profiles, but may have different reported frequencies.

Cost

• Generic Acyclovir is typically lower-priced per tablet; generic Valacyclovir usually costs somewhat more. Because Acyclovir can require more doses, per-tablet and per-course pricing don't always rank the same way.

Both Acyclovir and Valacyclovir work by keeping the herpes virus from making copies of itself.

Clinical guidelines recommend starting a prescription antiviral at the first sign of symptoms to help shorten the duration of an outbreak.

Neither one clears the virus from your body, but treatment may help make living with herpes a lot less disruptive.

If you get recurrent outbreaks, your provider may discuss suppressive antivirals to help manage how often they happen.

Valacyclovir vs. Acyclovir dosing schedules

Here's where the absorption difference becomes something you actually feel day to day. Both medications are dosed differently depending on what's being treated and whether you're managing an active outbreak or taking something daily to help manage recurrences.

Acyclovir is available in 400 mg and 800 mg tablets, and Valacyclovir in 500 mg and 1000 mg tablets, and which strength you end up with depends on the indication.

Those are the available strengths, not a prescription: the dose that's right for you, plus how often you take it and for how long, comes from a provider.

No matter which one you take, consistency is key—missing doses can affect how well the medication works.

Side effects of Acyclovir and Valacyclovir

Side effects are often mild, though they vary from person to person.

Common side effects of Acyclovir

Commonly reported side effects of Acyclovir can include:

• Nausea
• Vomiting
• Diarrhea
• Headache

This is not a complete list of risks and side effects, and others may occur. If symptoms worsen or you notice signs of an allergic reaction, contact a provider right away.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

Common side effects of Valacyclovir

Because it converts to the same active drug, Valacyclovir has similar side effects, though the reported frequencies may differ.

Commonly reported side effects of Valacyclovir can include:

• Headache
• Nausea
• Stomach pain

This is not a complete list of risks and side effects, and others may occur. If symptoms worsen or you notice signs of an allergic reaction, contact a provider right away.

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.

Cost difference without insurance

Cost is a legitimate deciding factor, and pretending otherwise would be silly.

Both medications are available as generics, which changed the math considerably from the days when branded options were on the shelf.

Generic Acyclovir is typically the lower-priced of the two per tablet. Generic Valacyclovir usually costs somewhat more per tablet.

One wrinkle: the cheaper tablet isn't automatically the cheaper course. Acyclovir may require more frequent dosing, so you may be buying more of them, and per-tablet price and per-course price don't always rank the same way.

Insurance formularies also differ, and pharmacy discount programs can shift what you actually pay at the counter. Prices vary by pharmacy and by region, so it’s worth checking a couple of options rather than assuming.

So which one actually works faster?

This is the question everyone actually types into Google, so here’s the straight answer: neither Acyclovir nor Valacyclovir is positioned as the speed option, and using Valacyclovir versus Acyclovir is a scheduling decision more than a timing one, which a provider can help you with.

What does matter for timing is when you start.

Clinical guidelines recommend starting either medication at the first sign of symptoms, when episodic treatment is used to help shorten the duration of an outbreak.

Waiting until day four of a full-blown flare-up is what usually costs you time, not which tablet you picked.

How to choose between Valacyclovir and Acyclovir

Good news: this isn't actually your call to make alone, and that's a reassurance once you stop trying to solve it at 1 a.m.

A provider chooses between Acyclovir and Valacyclovir based on things that are genuinely clinical, and most of them aren't obvious from the outside.

What they can be weighing:

• Which condition is being treated and whether this is a first episode or a recurrence
• Whether you need episodic treatment for an active outbreak or daily suppressive dosing
• Your kidney function
• Your other medications and possible drug interactions
• Whether managing transmission risk to a partner is part of the goal, since that indication belongs specifically to Valacyclovir.

Your lifestyle genuinely matters in that conversation; it's just not the only input.

A schedule you can realistically keep is part of what makes a plan appropriate, so if a five-times-daily regimen is never going to survive your actual week, that's clinical information, not a confession. Say it out loud.

What to bring to the provider consult

You don't need to arrive with a decision. You do need to arrive with the details that shape one, so it helps to have these ready:

• How many doses a day you can realistically manage. Be honest rather than aspirational.
• Any kidney problems, or other health conditions and medications you're taking. Both antivirals may need dosage adjustments if kidney function is reduced.
• Whether you're treating an active outbreak or hoping to manage how often recurrent outbreaks show up. These are different goals with different dosing.
• Whether a partner's risk is part of the picture. It may change which medication is on the table.
• Whether this is your first outbreak. If it is, you have a couple of ways to get started:
• A provider may be able to obtain a visual diagnosis through the medical intake.
• You can use an at-home swab test to collect a sample from an active sore, which can help identify the type of herpes that may be causing it. If your result comes back positive, it can lead to a consultation with a provider, who can help review your results and talk through next steps.

Whether that's an in-person visit or a virtual consult, the point is that you're not reverse-engineering this from a comparison chart by yourself.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary.

Two names and zero reason to figure it out alone

Both Acyclovir and Valacyclovir are used to manage herpes, and neither one clears the virus from your body, but treatment may help manage outbreak symptoms.

Acyclovir has the longer track record; Valacyclovir has the lighter dosing schedule. Cost and absorption are key factors, too.

The thing is, you don't have to weigh all of that on your own, because a provider can look at your history, your kidney function, and what you're actually treating, then determine which option is appropriate for you.

Not sure where to start? Wisp offers judgment-free online care with licensed providers, so you can skip the in-person waiting room entirely. If medically necessary and appropriate, a provider can prescribe antiviral treatment for [oral herpes](/products/valacyclovir-and-acyclovir-cold-sores and genital herpes, delivered free to your door, or with your prescription sent to your pharmacy the same day.

Most prescriptions are sent to your pharmacy within 3 hours of completing your patient intake form and secure chat or video call when necessary. Pending retail pharmacy hours.

Wisp is not affiliated and does not sponsor or endorse any company names, logos, or brands shown or mentioned. All product names, logos, brands, and other trademarks or images shown or mentioned are the property of the respective brand owners and are only used to identify the products and services of their respective owners.

This blog post is for informational and educational purposes only and should not be taken as professional advice. Always consult with a qualified professional before making any decisions based on the information provided here.