How often you take Valtrex (valacyclovir) depends entirely on what you’re treating. For cold sores, you take it just twice in a single day. For a genital herpes outbreak, you take it once or twice daily for several days. For long-term suppression, you take one pill every day, indefinitely. The dose, frequency, and duration all shift based on whether you’re treating a first episode, a recurrence, or trying to prevent outbreaks altogether.
Cold Sores: A One-Day Treatment
Cold sore treatment with Valtrex is the shortest course available. The FDA-approved dose is 2 grams twice in one day, spaced 12 hours apart. That’s it: two doses, one day, done. The key is starting at the very first sign of a cold sore, like tingling, itching, or burning on the lip. Once blisters have already formed, the medication is far less effective.
First Genital Herpes Outbreak
A first episode of genital herpes is typically more severe and longer-lasting than future outbreaks, so the treatment course is more aggressive. The standard regimen is 1 gram twice a day for 7 to 10 days. If sores haven’t fully healed after 10 days, treatment can be extended. This is the longest outbreak-treatment course you’d take.
Recurrent Genital Herpes Outbreaks
Repeat outbreaks tend to be milder, so the treatment window is shorter. There are two options:
- 500 mg twice a day for 3 days
- 1 gram once a day for 5 days
Both work best when you start taking the medication as soon as you feel symptoms coming on. Many people keep a supply on hand so they can begin treatment immediately rather than waiting for a prescription.
Daily Suppressive Therapy
If you get frequent outbreaks (generally six or more per year), daily suppressive therapy can significantly reduce how often they occur and lower the risk of transmitting the virus to a partner. This means taking Valtrex every single day, not just during outbreaks.
The suppressive dose is either 500 mg or 1 gram once daily, depending on your outbreak frequency and immune status. People with fewer than 10 outbreaks per year often start at 500 mg daily, while those with more frequent episodes or who are focused on reducing transmission risk may take 1 gram daily. This regimen continues indefinitely for as long as suppression is needed. There’s no built-in time limit, and long-term daily use has been studied for years without major safety concerns in people with normal kidney function.
Why Valtrex Is Taken Less Often Than Older Antivirals
Valtrex is a newer form of acyclovir, the original antiviral for herpes. The difference comes down to how well each drug is absorbed. Acyclovir has an oral bioavailability of only 15 to 30 percent, meaning most of the pill passes through without reaching the bloodstream. Valacyclovir raises that figure to roughly 70 percent, a three- to five-fold improvement. Because more of the drug actually gets into your system with each dose, you don’t need to take it as frequently. Acyclovir for genital herpes requires dosing five times a day; Valtrex achieves similar results with one or two doses.
Timing Matters More Than Extra Doses
Taking Valtrex more often than prescribed won’t make an outbreak heal faster. The medication works by blocking the virus from copying itself, and once you’ve reached the effective drug level in your blood, additional doses don’t add benefit. What does matter is how quickly you start. For both cold sores and genital herpes, the window between first symptoms and treatment initiation has the biggest impact on how well the drug works. Starting during the tingling or prodrome phase, before visible sores appear, gives you the best chance of shortening or even preventing a full outbreak.
If you miss a dose during an active treatment course, take it as soon as you remember and continue with the regular schedule. Don’t double up to compensate.
Kidney Function and Dose Adjustments
Valacyclovir is cleared through the kidneys, so people with reduced kidney function need lower doses or longer intervals between doses. This is particularly important for older adults, who are more likely to have decreased kidney function without realizing it. If you’re on daily suppressive therapy, your prescriber will likely check kidney function periodically. Staying well hydrated while taking the medication helps your kidneys process it efficiently, especially at higher doses like the 4-gram single-day cold sore regimen.