Acyclovir vs Valacyclovir: Which Is Better?

If you’re experiencing a viral herpes outbreak or working to get a herpes infection under control, you want the best medication you can get. Many men smartly seek medical advice to ensure that they can best care for their oral herpes, genital herpes, and the varicella-zoster virus generally. So, what works the best?

Acyclovir and valacyclovir are very similar. In fact, valacyclovir converts to acyclovir in your body after you take it. But, at least based on a few key criteria, valacyclovir has an edge on its competition.

Below we’ve covered the differences and similarities between two of the most commonly prescribed medications for herpes viral outbreaks: acyclovir and valacyclovir, as well as their common side effects, drug interactions, and which prescription medication you may want to consider.

Prescription drugs for the treatment of herpes like valacyclovir and acyclovir are antiviral drugs, which inhibit the virus from multiplying (or reproducing).

Drugs for herpes simplex virus 1 or herpes simplex virus 2 (HSV-1 or HSV-2) infections don’t cure herpes, but they can get outbreaks under control and treat their symptoms. These antiviral herpes drugs can also be used as part of a suppressive therapy plan to reduce outbreak severity and frequency.

Now let’s look at each one in more detail.

What Is Acyclovir?

Acyclovir, or ACV, is an older antiviral medication commonly used to treat herpes. It’s effective against HSV-1, HSV-2, and shingles.

Acyclovir — which was initially sold under the name Zovirax Ⓡ — was discovered in the 1970s, when it became the most widely used option until alternative antiviral drugs like valacyclovir took its place as the standard for modern herpes management.

What Is Valacyclovir?

Valacyclovir is one of the most (if not the most) widely used drugs worldwide for treating herpes, and has been since 1995, when it gained approval by the Food and Drug Administration (FDA). Most people know this drug as the brand name medication Valtrex Ⓡ, though generic versions are easier to come by these days.

Valacyclovir is what’s referred to as a prodrug of acyclovir, meaning it converts to acyclovir inside of your body. So, after you take a valacyclovir tablet, your body turns it into acyclovir, which then blocks the herpes virus from reproducing.

There’s a clearer winner in the valacyclovir vs. acyclovir debate. While both are safe and have been proven effective as treatments for herpes zoster, shingles, chickenpox and more, your healthcare provider will often prescribe valacyclovir for several reasons. 

Like other herpes medications, valacyclovir has shown great results. Studies show it reduces the amount of time required for healing during an outbreak and that it reduces your risk of transmitting the herpes virus to other people.

The effects of acyclovir are basically the same as valacyclovir (remember that one converts to the other). Setting aside clinical trial results and double-blind data from these studies, however, there are some practical reasons that you might prefer one medication to another.

What sets valacyclovir apart is that it works almost immediately, and its effects may also last longer than the effects of other medications. 

In fact, one of main reasons to choose valacyclovir over acyclovir for herpes and cold sores is because of its improved bioavailability (another word for how much of the drug is absorbed), which allows a lower dose of the drug to be used in treatment.

For example, one study showed that a 500mg dose of valacyclovir is as effective as a 800mg dose of acyclovir in preventing recurrence of herpes simplex virus-related eye disease.

Acyclovir is almost completely broken down by the liver when taken as an oral tablet, leaving it a bioavailability of just about 12 percent. Meanwhile, a valacyclovir tablet can have an oral bioavailability of approximately 50 percent.

Another way to look at it? More of the oral valacyclovir makes it into your body in the first place, which means that you can potentially take it fewer times per day or week to get the same results.

Side effects for both medications are generally mild and limited when the medication is used correctly.

The side effects of valacyclovir include:

• Headache

• Abdominal pain

• Nausea

Side effects of acyclovir reported by users include:

• Diarrhea 

• Headache

• Nausea 

Of course, both medications should be used only as directed. You should certainly let a healthcare professional know if you have other viral infections, kidney disease or HIV, or are immunocompromised. 

People who are breastfeeding should not take either medication without talking to a healthcare professional first.

Whether you’re dealing with the lesions from a particularly aggressive strain of shingles or the unfortunate symptoms of a herpes simplex virus breakout, you’re going to want some medication to help you deal with those uncomfortable blisters ASAP. Medications like acyclovir and valacyclovir are among your best options to deal with them.

If you think you might have herpes, you’ll first want to speak to your healthcare provider about treatment options. Your doctor will be able to provide advice on the most effective drug for treating herpes based on your symptoms, immune system, lifestyle, and overall health.

To feel better informed, here are some guidelines to keep in mind before speak with your healthcare provider:

• Both antivirals for herpes are effective, and they even share some DNA, as your body breaks valacyclovir down into acyclovir.

• Oral valacyclovir will likely be the first medication prescribed to you for a herpes outbreak or the management of recurrent genital herpes. It’s cheap, effective and readily available, as well as newer and more bioavailable than acyclovir.

• None of the antiviral drugs on the market today can cure herpes. Still, consistent use of an antiviral drug can make living with herpes much easier by speeding up healing after an outbreak and reducing your risk of transmitting the virus to other people.

Our valacyclovir 101 guide shares more information on this drug, including common dosages, potential side effects, interactions, and brand names.

We’ve also got valuable information on valacyclovir dosages, how long valacyclovir takes to work, and sexual health questions, like whether it’s safe to be having sex with herpes. 

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