Key takeaways:
Valtrex (valacyclovir) is an antiviral medication used for many viral infections. It treats cold sores, genital herpes, shingles, and more. The recommended Valtrex dosage depends on your age and what condition you’re taking it for.
Cold sores typically require just 1 day (2 doses) of Valtrex treatment. Gential herpes, shingles, and chickenpox typically require 3 to 10 days of treatment. Dosages are lower for people with kidney problems.
Valtrex is available as a lower-cost generic. GoodRx can help you save over 70% off the average retail price at certain pharmacies.
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Valtrex (valacyclovir) is a prescription-only antiviral medication that treats health conditions caused by the herpes simplex virus (HSV). This includes viral infections caused by HSV-1, such as cold sores — also called fever blisters. It also includes HSV-2 infections, such as genital herpes. Valtrex also treats infections caused by the herpes zoster virus, such as shingles and chickenpox. All of these viral conditions can cause a “herpes outbreak,” which is a flare-up of symptoms that range from lip blisters to painful skin rashes.
Valtrex is an effective option for managing herpes breakouts. It works by preventing the herpes virus from making copies of itself. This makes it easier for your body to manage the infection and stop it from spreading.
When it comes to actually taking Valtrex, the recommended Valtrex dosage varies by situation. Here, we’ll review the recommended Valtrex dosages along with what to do if you miss a dose or take more than recommended.
What’s the typical Valtrex dosage for adults?
The typical Valtrex dosage for adults depends on what health condition you’re taking it for. It comes as a brand-name or generic tablet in two doses: 500 mg and 1,000 mg (1 gram).
Valtrex dosage for cold sores (fever blisters)
The recommended Valtrex dosage for fever blisters is 2 grams by mouth every 12 hours for 1 day. This means you’ll either take four 500 mg tablets or two 1 gram tablets per dose.
You should take Valtrex as soon as you notice symptoms of a cold sore, such as tingling, itching, or blisters forming on or around the lip area. Taking Valtrex early on in the development of a cold sore allows it to work best. It also helps cold sores heal faster.
Valtrex dosage for treating herpes simplex outbreaks
The recommended Valtrex dosage for genital herpes depends on your history of herpes outbreaks.
Your first outbreak of genital herpes is typically more severe, so you’ll likely take a higher Valtrex dose initially. Recurrent (repeat) outbreaks are usually less severe if they occur, and you can often find relief with a lower dose.
The recommended Valtrex dosages for genital herpes include:
Your first outbreak: Take 1 gram by mouth twice daily for 10 days.
Recurrent outbreak: Take 500 mg by mouth twice daily for 3 days.
For best results, you should take Valtrex as soon as you experience symptoms of genital herpes, such as itching or blistering on the genitals. Starting treatment within 48 hours (2 days) will help it work its best.
Valtrex dosage for preventing herpes simplex outbreaks
Unfortunately, genital herpes isn’t curable. The virus lies dormant (inactive) in nerve cells and can be reactivated at any time, leading to recurrent outbreaks. But you can lower your chances of outbreaks by taking Valtrex every day. Taking Valtrex daily can also lower the chances of spreading genital herpes to other people.
The recommended Valtrex dosages to prevent genital herpes outbreaks are:
To lower the chance of recurrent outbreaks: Take 1 gram by mouth once daily. If you have fewer than 10 outbreaks per year, you may take a lower dose of 500 mg once daily. But certain people with HIV should take 500 mg by mouth twice daily.
To lower the chance of spreading genital herpes to others: Take 500 mg by mouth once daily.
Options are important: Learn about famciclovir (Famvir), a similar antiviral, and how it stacks up to valacyclovir (Valtrex) for cold sores.
Experiencing a herpes outbreak? Here’s what you need to know about how long an outbreak may last.
Take control of your sexual health: Read up about recognizing the signs and symptoms of a sexually transmitted infection (STI) — and when to get tested.
Your healthcare professional can help you choose the best dosage strategy for your situation.
Valtrex dosage for shingles
The recommended Valtrex dosage for shingles is 1 gram by mouth 3 times daily for 7 days. You should start the medication as soon as you notice symptoms of shingles, such as pain, tingling, or a red rash on one side of your body.
Valtrex is most effective for shingles when taken within 48 hours of developing your first symptoms. It may also be effective up to 72 hours (3 days) after your symptoms start. You can also take it after 72 hours if new shingles lesions develop or you have a weakened immune system.
What’s the typical Valtrex dosage for children?
Valtrex can treat cold sores and chickenpox in children. Valtrex dosages in children can be the same or different from adults. Valtrex only comes as oral tablets. But if your child has trouble swallowing pills, ask your child’s prescriber about the compounded oral suspension. This requires the pharmacy to compound (custom-make) an oral liquid for your child. But it can be a helpful option for those who can’t swallow pills.
Valtrex dosage for cold sores (fever blisters)
For cold sores, children ages 12 and older are recommended to take 2 grams by mouth every 12 hours for 1 day. Kids should take Valtrex as soon as cold sore symptoms start. Valtrex isn’t approved for treating cold sores in children younger than age 12.
Valtrex dosage for chickenpox
Valtrex’s dosage for chickenpox is determined based on your child’s body weight. Valtrex is only recommended for children ages 2 to 17 years old. Kids younger than age 2 shouldn’t take it.
The typical Valtrex dosage for chickenpox in children is 20 mg per kg of body weight 3 times daily for 5 days. For example, a child weighing 40 kg (88 lbs) would take 800 mg 3 times a day. The dose shouldn’t exceed 3 grams per day.
Good to know: Since the chickenpox vaccine became widely available in 1995, cases in the U.S. have gone down by 97%. But if your child contracts chickenpox, treatment with Valtrex should start as soon as possible. Try to give them their first dose within 24 hours (1 day) of their chickenpox rash onset.
Are there any Valtrex dosage adjustments for medical conditions?
Yes, Valtrex dosage adjustments are recommended for certain people with kidney problems. This is because your kidneys are responsible for clearing Valtrex from the body. If they’re not working as well as they could, Valtrex won’t leave your body as efficiently as usual. This can lead to higher Valtrex levels in the body, which raises your risk of side effects.
What’s more, Valtrex itself can harm the kidneys. It may lower kidney function, especially in older adults. This risk is also higher for people already living with kidney problems who are taking high doses of Valtrex or other medications that can harm the kidneys.
Valtrex dosage for people with kidney problems
If you have kidney problems, your healthcare professional will determine your Valtrex dose based on your kidney health. But it’s hard to know your specific level of kidney function without a lab test.
Your healthcare professional can assess your kidney function by checking your blood level of a natural waste product called creatinine. If you have more creatinine than expected (a lower “creatinine clearance”), your kidneys aren’t as efficient as they could be. In this case, you’ll likely get a lower Valtrex dose.
For example, if you have kidney problems and need to take Valtrex for cold sores, you may need to lower your dose to 1 gram every 12 hours for 1 day. This is half of the dose recommended for people with normal kidney function. More examples are provided in the table below.
Creatinine clearance | Cold sores | Genital herpes (first outbreak) | Shingles |
|---|---|---|---|
30-50 mL/min | 1 gram every 12 hours for 2 doses | No dose adjustment needed | 1 gram every 24 hours |
10-29 mL/min | 500 mg every 12 hours for 2 doses | 1 gram every 24 hours | 1 gram every 24 hours |
Less than 10 mL/min | 500 mg as a single dose | 500 mg every 24 hours | 500 mg every 24 hours |
What happens if you miss a dose of Valtrex?
If you miss a dose of Valtrex, you should take it as soon as you remember. But if you remember a few hours before your next scheduled dose, don’t take the missed dose. You should skip the missed dose altogether and wait to take the next dose at your regular scheduled time.
Can I double my Valtrex dosage?
No, do not try to catch up by taking a double dose of Valtrex. You should only take one dose at a time. Taking too many doses at once can cause more side effects.
What should you do if you take too much Valtrex?
If you take too much Valtrex, you may be at risk for experiencing more Valtrex side effects. Nausea, vomiting, and headache are common examples.
In some cases, Valtrex toxicity is also possible. This is more likely to happen to people with kidney problems who take too much Valtrex. Valtrex toxicity can lead to serious kidney and/or nervous system problems and requires immediate medical attention.
Symptoms to look out for include:
Peeing less than usual or not peeing at all
Aggressive behavior
Unsteady or shaky movements
Speech problems
Confusion
Hallucinations (seeing or hearing things that aren’t a reality for other people)
Coma
If you think you’ve taken too much Valtrex, call your healthcare professional or contact Poison Control online or at 1-800-222-1222. However, if your symptoms feel severe, it’s better to call 911 or go to the nearest ER.
How to save on valacyclovir
There are ways to save on Valtrex, which is available as both a brand-name and generic medication. GoodRx can help you save over 70% off the average retail price of the generic version. Generic valacyclovir at certain pharmacies is as low as $18.90 for 30 tablets with a free GoodRx coupon.
Frequently asked questions
It typically takes about 2 to 3 days for Valtrex to make a noticeable difference in shingles symptoms. And it can help cold sores heal about 1 day faster than no treatment. But in order for Valtrex to work its best, you should start it as soon as possible after symptoms appear.
Valacyclovir is a prodrug of acyclovir. This means it’s converted into acyclovir in your stomach and intestines after you take it. So they work the same way in your body. But valacyclovir is absorbed better than acyclovir. So the biggest difference between these medications is how often you need to take them. For example, you’ll typically take valacyclovir 3 times a day for shingles, but you’ll need to take acyclovir 5 times a day for this condition.
Valtrex is generally well tolerated. The most common side effects include headache, nausea, and stomach pain. Taking Valtrex with food can help. It’s also important to stay hydrated while taking Valtrex to help protect your kidneys.
It typically takes about 2 to 3 days for Valtrex to make a noticeable difference in shingles symptoms. And it can help cold sores heal about 1 day faster than no treatment. But in order for Valtrex to work its best, you should start it as soon as possible after symptoms appear.
Valacyclovir is a prodrug of acyclovir. This means it’s converted into acyclovir in your stomach and intestines after you take it. So they work the same way in your body. But valacyclovir is absorbed better than acyclovir. So the biggest difference between these medications is how often you need to take them. For example, you’ll typically take valacyclovir 3 times a day for shingles, but you’ll need to take acyclovir 5 times a day for this condition.
Valtrex is generally well tolerated. The most common side effects include headache, nausea, and stomach pain. Taking Valtrex with food can help. It’s also important to stay hydrated while taking Valtrex to help protect your kidneys.
The bottom line
Valtrex (valacyclovir) is a prescription medication used to treat viral infections such as genital herpes, cold sores (fever blisters), and shingles. Valtrex dosages depend on what you’re taking it for, your age, and if you have kidney problems. Cold sores typically require just 1 day (2 doses) of Valtrex treatment. Gential herpes, shingles, and chickenpox typically require 3 to 10 days of treatment. Speak with your healthcare professional about the best Valtrex dosage for your situation.
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References
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MedlinePlus. (2018). Valacyclovir.
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