Valacyclovir Dosage Guide

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

Valacyclovir hydrochloride (also known by the brand name ValtrexⓇ) is a type of antiviral medication approved by the Food and Drug Administration (FDA) for the management of herpes simplex virus (HSV) outbreaks. You might also take valacyclovir for cold sores, genital herpes, or even shingles. 

It can work for all of them — if you take the right valacyclovir dosage. Below, we’ve collected the relevant pharmacokinetics and drug information regarding the Valtrex dosage you may be prescribed depending on what you’re trying to treat.

Before we dive into the details about valacyclovir dosage, it’s important to understand a few things about how valacyclovir works and how it can be taken.

Valtrex, or its generic valacyclovir, is a nucleoside analogue treatment that prevents the herpes virus from replicating. This lessens the severity of outbreaks and helps reduce your chances of passing the virus to someone else. In the process of this treatment, valacyclovir is converted into a similar compound by your body called acyclovir, which is also used to treat herpes.

Valacyclovir comes in several dosage forms for oral administration, from film-coated capsules to tablets. It’s also offered in several different doses. 

According to the FDA, valacyclovir's half-life (the time it takes your body to process the medication down to half its concentration) is between 2.5 and 3.3 hours.

Valacyclovir is highly effective in the treatment of cold sores, also known as oral herpes or herpes labialis. 

If started at the first sign of the formation of a cold sore, valacyclovir taken repeatedly as directed can reduce the amount of time required for a cold sore to heal.

When it comes to the Valtrex dosage for cold sores in adults, the FDA recommends a dose of 2 grams (g) every 12 hours. This Valtrex oral herpes dosage can also be prescribed as 2,000 milligrams (mg) tablets, with a second dose of 2,000 mg taken within 12 hours. 

Studies show that this repeated high dose of valacyclovir can quickly end viral replication, which is when the virus mass produces itself and causes more symptoms. In turn, this allows cold sores to heal one to two days faster than they normally would, effectively stopping a cold sore in its tracks.

Genital herpes occurs in two phases: an initial outbreak with severe symptoms, followed by recurrent genital herpes outbreaks every few months. People with an HSV infection can experience as many as four to five outbreaks a year — though luckily, valacyclovir is also highly effective at treating genital herpes. 

Your valacyclovir dosage will depend on which type of outbreak you’re dealing with:

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

• For recurrent genital herpes, a valacyclovir dosage of 500 mg should be taken twice daily for three days. This Valtrex dosage is most effective when taken as early as possible, close to the start of the outbreak.

Shingles may not have the same stigma as other types of herpes, but it’s still a variation of the herpes virus, and it can also be treated with valacyclovir. Also known as herpes zoster, shingles is caused by the same virus that causes chickenpox: the varicella-zoster virus. 

However, shingles tends to occur in adults, and it can require more treatment than is needed for the treatment of chickenpox in kids, especially those who are just a few years of age. And while recurrent episodes of shingles are extremely rare and occur mostly in people with weakened immune systems, they do happen.

The standard recommended dose of valacyclovir used to treat shingles is 1,000 mg three times a day. Treatment of herpes zoster may take about seven days, though you may be told to take the medication for longer if it’s slower to work.

Valacyclovir is also used for suppressive therapy against herpes, which is 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. (If you were worried about having sex with herpes, this is likely very good news). 

For the purpose of suppressive therapy, what’s standard is a valacyclovir 1 gm dosage 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 — think valacyclovir 500 mg daily.

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.

Overall, remember to use common sense. You can take a missed dose a bit late if you forget it, but otherwise, just wait until your next dose — don’t take two doses too close together. And don’t take more than the prescribed dosage in a single day. In other words, if you’re wondering ‘Can I double my valtrex dosage for cold sores?,” the answer is likely no.

Most importantly, if you are 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 Valtrex dosage recommendations based on age and weight to avoid toxicity and adverse effects.

Taking the right valacyclovir dosage is just part of the safe use of this medication. 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.

While valacyclovir is generally safe for immunocompetent patients, those who are immunocompromised (such as those with an HIV infection or autoimmune conditions) may not be able to take this medication safely. 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. 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 also shouldn’t be used by those who have undergone bone marrow transplants.

Further, pregnant women should not take valacyclovir, nor should those who are breastfeeding, as it can transfer to breast milk.

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 valacyclovir 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’s targeted to your individual needs.

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

Here’s what to remember when it comes to Valtrex dosage:

• You’ll take this medication differently to manage herpes than you would during an initial episode. Recurrences often require a lower valacyclovir dosage.

• People with kidney problems or those on dialysis should not take valacyclovir, nor should those with an HIV infection or a 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.

If you have further sexual health questions, we can help.