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Valacyclovir Dosage Guide

Kristin Hall, FNP

Reviewed by Kristin Hall, FNP

Written by Geoffrey C. Whittaker

Published 05/30/2018

Updated 10/19/2023

Whether you’ve been struggling with a form of herpes for a while or are just beginning to navigate treatment, you’re about to hear a lot about a medication called valacyclovir.

Valacyclovir hydrochloride (also known by the brand name Valtrex), is a nucleoside analogue treatment — a type of antiviral medication — approved by the Food and Drug Administration for the management of herpes simplex outbreaks.

That’s a long way of saying it prevents the herpes virus from replicating, which lessens the severity of outbreaks and helps reduce your chances of passing the virus to someone else.

While you may most readily associate Valtrex with herpes outbreaks that affect your sex life, in reality, you might take valacyclovir to treat genital herpes, cold sores (herpes labialis) or even shingles (a form of chickenpox known as herpes zoster). 

It works for the management of all of them — if you take the right dosage.

What that dosage is depends on what you’re treating. Valacyclovir comes in several forms for oral administration, from film-coated capsules to tablets, and in several doses. Below, we’ve listed common Valtrex dosages for a variety of conditions, such as oral or genital herpes. 

Oral herpes is the most common form of the herpes virus, affecting approximately two thirds of all people aged 14 to 49 according to the World Health Organization.

Valacyclovir is highly effective at treating oral herpes. If taken at the first sign of the formation of a cold sore, repeated use of valacyclovir as directed can reduce the amount of time required for a cold sore to heal.

The FDA recommends a dose of valacyclovir of 2g every 12 hours, which can also be taken as a dose of 2,000mg with a second dose of 2,000mg within 12 hours. 

Studies show that this repeated high dose of valacyclovir can quickly end viral replication (where the virus mass produces itself and causes more symptoms), allowing cold sores to heal one to two days faster than they normally would.

Genital herpes may be less visible to the public than oral herpes, but they’re no less embarrassing to struggle with — and they’re frequently more uncomfortable, too. 

Genital herpes occurs in two phases: an initial outbreak with severe symptoms, followed by recurrent genital herpes outbreaks every few months.

People infected with genital herpes can experience as many as four to five outbreaks a year, though, luckily, valacyclovir is also highly effective at treating genital herpes. 

Your dosage will be based based on which type of outbreak you’re dealing with:

  • The dose of valacyclovir for an initial outbreak is 1,000mg two times per day for 10 days, which gives the herpes lesions time to heal.

  • For recurrent genital herpes, 500mg should be taken twice daily for three days — it’s most effective when taken as early as possible, close to the start of the outbreak.

It may not have the same stigma as other types of herpes, but shingles is a variation of the herpes virus that can occur in adults. This type of herpes can also be treated with valacyclovir.

A quick note: while recurrent episodes of shingles are extremely rare and occur mostly in people with weakened immune systems, they do occur.

The standard recommended dose of valacyclovir used to treat the varicella-zoster virus, which is what causes shingles, is 1,000mg three times a day for seven days, though you may be told to take it for longer if the medication is taking longer to work.

Valacyclovir is also used for suppressive therapy against herpes — a method of reducing your risk of spreading herpes to a partner or family member, and of restricting the virus from causing frequent outbreaks in the first place. 

In other words, valacyclovir may also reduce your risk of spreading herpes to others.

A standard dose of valacyclovir for the purpose of suppressive therapy is 1,000mg (one gram) taken once daily. 

You’ll notice that this dose is much smaller than those used for outbreak management. People with either form of herpes simplex (sometimes referred to as HSV-1 and HSV-2) who experience infrequent outbreaks may be prescribed an even lower daily dose of about 500mg.

Valacyclovir is an affordable, highly effective antiviral medication, making it the “gold standard” for treating outbreaks of herpes and reducing the risk of infecting others with the virus.

However, it’s important to speak to your healthcare provider before taking valacyclovir to treat any infection, including herpes, and to let them know if you experience side effects. Common side effects of valacyclovir are generally mild and limited to headache, nausea and abdominal pain, but more can occur if you take the medication incorrectly.

Taking the right dose is just part of the safe use of valacyclovir. It’s also important to know about the contraindications that may make it dangerous to take and what might happen if you take it the wrong way.

For instance, people who are immunocompromised (such as those with an HIV infection or autoimmune conditions) may not be able to take this medication safely.

Valacyclovir can cause hepatic (liver) injuries, and it should not be used by people who have recently undergone a kidney transplant, as it can potentially cause renal impairment and acute renal failure. It should also not be used by those who have undergone bone marrow transplants, pregnant women or those who are breastfeeding, as it can transfer into breast milk. 

It’s particularly important to speak to your healthcare provider before using valacyclovir if you have HIV, because your risk of developing a blood disorder called thrombotic thrombocytopenic purpura is increased. Also be sure to tell your doctor if you have any health condition that can cause reduced kidney or immune function.

Overall, remember to use common sense. You can take a missed dose a bit late if you forget it, but don’t take two doses too close together. And don’t take more than the prescribed dosage in a single day.

Most importantly, if you have been prescribed valacyclovir by your healthcare provider to treat any condition, follow the dose and frequency they recommend. This information is provided as a reference only — you should always follow your doctor’s advice when using any prescription medication.

FYI: the dosage information provided above is for adults — for pediatric patients, you should consult a healthcare provider, who will provide dosing recommendations based on age and weight to avoid toxicity and adverse effects.

If a healthcare professional has prescribed you valacyclovir as a treatment for some form of blisters related to herpes infections, they’ve likely already told you what dosage to use and how often to take that dosage to treat your symptoms. 

That guidance is the best anyone can offer you, because it will be targeted to your individual needs. 

Overall, valacyclovir is an extremely safe, well-studied medication. Its side effects are mild and rare, affecting only a small percentage of users. For most people, it’s also very safe for the liver and other internal organs, including those commonly affected by other medications.

Here’s what to remember:

  • You’ll take this medication differently to manage herpes than you will during your initial episode. Recurrences often require less medication.

  • People with kidney problems or those on dialysis should not take valacyclovir, nor should those with an HIV infection or compromised immune system. This medication can affect normal renal function, and even a single dose can cause problems for immunocompromised patients.

  • Not sure what to do? Talk to your healthcare provider for tailored medical advice. Let them know of any other medications you’re taking, as well as any supplements, to avoid risks to your health.

Our valacyclovir 101 guide covers the ins and outs of how valacyclovir works in more detail, from how the drug reduces the spread of herpes and treats outbreaks to the potential side effects you may experience while taking valacyclovir to treat herpes.

And if you have further sexual health questions, we can help.

3 Sources

  1. Valtrex (valacyclovir hydrochloride) Caplets - Food and Drug Administration. (n.d.). https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/020487s014lbl.pdf.
  2. Spruance, S. L., Jones, T. M., Blatter, M. M., Vargas-Cortes, M., Barber, J., Hill, J., Goldstein, D., & Schultz, M. (2003). High-dose, short-duration, early valacyclovir therapy for episodic treatment of cold sores: results of two randomized, placebo-controlled, multicenter studies. Antimicrobial agents and chemotherapy, 47(3), 1072–1080. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC149313/.
  3. Nair PA, Patel BC. Herpes Zoster. [Updated 2023 Apr 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441824/.
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Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references. See a mistake? Let us know at [email protected]!

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Kristin Hall, FNP

Kristin Hall is a board-certified Family Nurse Practitioner with decades of experience in clinical practice and leadership. 

She has an extensive background in Family Medicine as both a front-line healthcare provider and clinical leader through her work as a primary care provider, retail health clinician and as Principal Investigator with the NIH

Certified through the American Nurses Credentialing Center, she brings her expertise in Family Medicine into your home by helping people improve their health and actively participate in their own healthcare. 

Kristin is a St. Louis native and earned her master’s degree in Nursing from St. Louis University, and is also a member of the American Academy of Nurse Practitioners. You can find Kristin on LinkedIn for more information.

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