Valacyclovir is a generic antiviral medication that is also available as the brand-name drug Valtrex. It is a tablet that you take by mouth. You need a doctor’s prescription for valacyclovir. It is not available over the counter.
Valacyclovir is prescribed to treat symptoms caused by the herpes viruses. This includes infections such as:
- cold sores
- genital herpes
- shingles
- chickenpox (in children)
If your doctor has prescribed valacyclovir, it’s important to take it according to their instructions.
This guide will explain the typical dosage of valacyclovir, how to take it, and what to keep in mind during treatment.
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What is the dosage of valacyclovir for adults?
The following chart lists valacyclovir prescription options. Your doctor will determine the best dosage for you based on your overall health, other medications you may be taking, and the condition you are taking the medication to treat.
Dosages in the table below are in milligrams (mg) and grams (g).
| Condition | Recommended dosage | How often to take |
| cold sore | 2 g | every 12 hours for 1 day (2 doses total) |
| shingles | 1 g | 3 times per day for 7 days |
| genital herpes, first episode | 1 g | 2 times per day for 10 days |
| genital herpes, recurrent episodes | 500 mg | 2 times per day for 3 days |
| genital herpes, to prevent flare-ups | 500 mg to 1 g | once per day |
| genital herpes, to prevent flare-ups in people with HIV | 500 mg | 2 times per day |
| genital herpes, to reduce risk of passing the virus to a sexual partner | 500 mg | once per day |
What is the dosage of valacyclovir for children?
The following chart outlines the typical valacyclovir dosage for children, depending on the condition it is prescribed to treat.
| Condition | Age | Recommended dosage | How often to take |
| cold sore | 12 years and older | 2 g | every 12 hours for 1 day (2 doses total) |
| chickenpox | 2 to 17 years | 20 mg per kilogram (kg) | 3 times per day for 5 days |
Note: For reference, 1 kg is equal to about 2.2. pounds (lb).
For the treatment of chickenpox, a doctor will use the child’s weight in kg to determine the correct dosage.
For instance, if a child weighs 15 kg (about 33 pounds), their dose of valacyclovir will be 300 mg. They will take this dose 3 times per day for 5 days.
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Get free cardHow to take valacyclovir
As an antiviral drug, valacyclovir helps manage the symptoms of various types of herpes infections. For best results, follow these steps:
- Follow your doctor’s instructions: Be sure to take valacyclovir exactly as your doctor or healthcare professional instructed. Don’t take more or less than your doctor has prescribed, and don’t stop taking it early unless your doctor tells you to.
- Take with or without food: Valacyclovir comes in tablet form that you take by mouth, either with or without food. If it upsets your stomach, try taking it with food or a glass of milk.
- Drink plenty of fluids: While taking valacyclovir, try to stay well-hydrated by drinking plenty of water throughout the day. This helps your kidneys process the drug and may reduce the risk of valacyclovir side effects.
- Stick to a schedule: Try to take your dose at the same time every day. If you’re taking valacyclovir more than once a day, space the doses out evenly (for example, every 12 hours). This helps to maintain a steady level of the drug in your body.
Summary
Valacyclovir is a generic antiviral drug prescribed to treat symptoms caused by herpes viruses. It comes as a tablet that you take by mouth.
The valacyclovir dosage will vary depending on what condition you are taking it to treat. For example, for a cold sore, you’ll take a total of 2 doses of valacyclovir spaced 12 hours apart. But for shingles, you’ll take it 3 times per day for 7 days, and for the first occurrence of genital herpes, you’ll take it 2 times per day for 10 days.
It’s important to take valacyclovir exactly as your doctor instructs. Don’t change your dose or stop taking it unless your doctor tells you to.