How often you take valacyclovir depends entirely on what you’re treating. The schedule ranges from a single day of high doses for cold sores to once-daily pills taken indefinitely for suppressive therapy. Here’s what each regimen looks like.
Why Dosing Varies So Much
Valacyclovir is a prodrug, meaning your body converts it into the active antiviral acyclovir after you swallow it. The reason it exists as a separate medication is efficiency: valacyclovir has roughly 54% bioavailability compared to just 15% to 30% for acyclovir taken by mouth. That higher absorption rate means you can take fewer pills per day and still get therapeutic levels of the drug working against the virus. Acyclovir itself often requires five doses spread throughout the day, while valacyclovir typically requires one to three.
Cold Sores: One Day of Treatment
For cold sores, valacyclovir uses the shortest and most aggressive schedule. You take 2 grams (four 500 mg tablets) at the first sign of a cold sore, then another 2 grams roughly 12 hours later. That’s it. The entire course is two doses in a single day.
Timing matters here. Starting at the earliest tingle or itch gives the drug the best chance of shortening the outbreak. Once a blister has fully formed, the benefit drops significantly. In clinical trials of this one-day regimen, headache was the most common side effect, reported by about 14% of people (compared to 10% on placebo).
First Genital Herpes Outbreak: Twice Daily for 10 Days
An initial genital herpes episode is typically the most severe, so the treatment course is longer. The standard regimen is 1 gram twice a day for 10 days. Starting treatment as soon as symptoms appear shortens healing time and reduces pain. In clinical trials of this regimen, headache (13%) and nausea (6%) were the most frequently reported side effects.
Recurrent Genital Herpes Outbreaks: Twice Daily for 3 to 5 Days
If you get occasional outbreaks and want to treat them as they come (sometimes called episodic therapy), the dose is 500 mg twice a day. The course lasts either 3 or 5 days depending on your prescriber’s recommendation. As with cold sores, you should start taking it at the very first sign of symptoms, whether that’s tingling, itching, or redness. Waiting even a day reduces how much the medication can help.
Daily Suppressive Therapy: Once a Day, Ongoing
Suppressive therapy is the most common long-term use of valacyclovir. You take it every day regardless of whether you’re having symptoms, with the goal of preventing outbreaks from happening in the first place. This approach reduces the frequency of recurrences by 70% to 80% in people who get frequent outbreaks.
The standard suppressive dose is 1 gram once daily. If you have 9 or fewer outbreaks per year, 500 mg once daily is an option. However, CDC guidelines note that the 500 mg dose may be less effective for people with 10 or more episodes per year, so the higher dose is generally preferred for frequent recurrences.
Suppressive therapy also reduces the risk of transmitting herpes to a sexual partner. In a clinical trial of couples where one partner had genital herpes and the other didn’t, taking 500 mg daily reduced the risk of symptomatic transmission by 75% and overall transmission by 48% compared to placebo. Many people stay on suppressive therapy for years. Your prescriber may suggest stopping periodically to reassess whether outbreaks return, since outbreak frequency often decreases naturally over time.
Side effects during long-term use are generally mild. In suppression trials, headache was reported by about 35% to 38% of participants (though placebo rates were nearly as high at 34%), nausea by about 11%, and abdominal pain by about 9% to 11%.
Shingles: Three Times Daily for 7 Days
Shingles requires the most frequent dosing. The regimen is 1 gram three times a day for 7 days. Treatment should begin within 72 hours of the rash appearing for the best results, as the drug works by stopping the virus from replicating during the active phase. Starting later can still provide some benefit, but early treatment is strongly associated with reduced pain duration and a lower risk of lingering nerve pain afterward.
What Happens if You Miss a Dose
If you’re on a multi-day or daily regimen and miss a dose, take it as soon as you remember. If it’s nearly time for your next scheduled dose, skip the missed one and continue your regular schedule. Don’t double up. For suppressive therapy especially, consistency matters because the drug works by maintaining steady levels that keep the virus from reactivating.
Spacing Your Doses
When a regimen calls for twice-daily dosing, aim for roughly 12 hours apart, such as morning and evening. For three-times-daily shingles treatment, spacing doses about 8 hours apart keeps drug levels more consistent. You can take valacyclovir with or without food, and staying well hydrated while on it helps your kidneys process the medication efficiently. People with reduced kidney function typically need adjusted doses or longer intervals between pills, which a prescriber will calculate based on kidney function tests.