Valacyclovir is taken by mouth, with or without food, and the dose depends entirely on what you’re treating. For a first outbreak of genital herpes, the standard dose is 1,000 mg (1 gram) twice a day for 10 days. For a recurrent episode, it’s 500 mg twice a day for just 3 days. If you’re taking it daily to prevent outbreaks, the typical dose is either 500 mg or 1,000 mg once a day. The key to getting the most out of this medication is starting it as early as possible and staying well hydrated throughout treatment.
Dosing by Condition
Your prescribed dose and schedule will vary based on the type and stage of herpes infection being treated. Here are the standard regimens from CDC and FDA guidelines:
- First genital herpes outbreak: 1,000 mg twice daily for 7 to 10 days
- Recurrent genital herpes (episodic treatment): 500 mg twice daily for 3 days, or 1,000 mg once daily for 5 days
- Daily suppressive therapy: 1,000 mg once daily for most people. If you have 9 or fewer outbreaks per year, 500 mg once daily is an option, though the lower dose may be less effective for people with 10 or more episodes annually.
- Cold sores: A high-dose, short course taken at the first sign of tingling
- Shingles: 1,000 mg three times daily for 7 days
Your prescriber may adjust these based on your kidney function, immune status, or how frequently you experience outbreaks. People living with HIV on suppressive therapy typically take 500 mg twice daily rather than once daily.
When Timing Matters Most
For episodic treatment of outbreaks, valacyclovir works best when you start taking it at the very first sign of symptoms. That means the tingling, itching, or burning sensation that often appears before sores develop. The medication doesn’t kill the virus, but it slows viral replication. The sooner you intervene in that process, the shorter and milder the outbreak tends to be.
If your prescriber has given you a prescription to keep on hand for recurrent episodes, fill it in advance so it’s ready when you need it. Waiting even a day to start can reduce effectiveness significantly. For daily suppressive therapy, timing is less urgent on any given day since the goal is maintaining a steady level of the drug in your system. Pick a consistent time, morning or night, and stick with it.
Food, Water, and Absorption
You can take valacyclovir with or without food. Meals don’t significantly affect how well your body absorbs the drug, so take it whichever way helps you remember and feels most comfortable on your stomach.
Hydration, on the other hand, is genuinely important. Once your body absorbs valacyclovir, it converts the drug into its active form, acyclovir, which is processed through the kidneys. Acyclovir doesn’t dissolve well in urine. If you’re not drinking enough water, the drug can form crystals in your kidney tubules, potentially causing a blockage and acute kidney injury. This is uncommon in healthy, well-hydrated people, but the risk is real enough that the FDA label specifically instructs patients to maintain adequate hydration. A good rule of thumb is to drink a full glass of water with each dose and keep your overall fluid intake steady throughout the day.
What to Do if You Miss a Dose
If you’re on a twice-daily or once-daily schedule and realize you’ve missed a dose, take it as soon as you remember. If it’s already close to the time for your next scheduled dose, skip the missed one and continue your regular schedule. Don’t double up to make up for it. Doubling doses increases the amount of drug your kidneys need to clear at once, which raises the risk of side effects without improving effectiveness.
For suppressive therapy, missing a single dose occasionally is unlikely to trigger an outbreak. But if you find yourself forgetting doses regularly, consider setting a daily alarm or pairing the dose with a routine you already have, like brushing your teeth.
How Long to Keep Taking It
For episodic treatment of outbreaks, finish the full course even if your symptoms improve before the pills run out. Stopping early can allow the virus to continue replicating, potentially prolonging the episode.
Daily suppressive therapy is a different conversation. Many people stay on it for months or years, particularly if they have frequent outbreaks or want to reduce the risk of transmitting the virus to a partner. There’s no built-in time limit. Some prescribers suggest reassessing once a year to see whether outbreaks have decreased enough to try stopping. Outbreak frequency often decreases naturally over time, especially in the first few years after initial infection.
Kidney Health and Who Needs Extra Caution
Because valacyclovir is cleared almost entirely through the kidneys, people with reduced kidney function typically need lower doses or longer intervals between doses. If you have known kidney problems, your prescriber will adjust your regimen based on how well your kidneys are filtering. Older adults are also more likely to have reduced kidney function even without a formal diagnosis, which is one reason this group faces a higher risk of side effects.
Signs of kidney trouble during treatment include a noticeable decrease in how much you urinate, swelling in your legs or feet, or unusual fatigue. Dehydration from illness, exercise, or hot weather can compound the risk. If you’re sick with vomiting or diarrhea while taking valacyclovir, making a deliberate effort to replace fluids is especially important.
Common Side Effects
Most people tolerate valacyclovir well. The most frequently reported side effects are headache, nausea, and abdominal pain. These tend to be mild and often improve as your body adjusts. Dizziness can also occur, particularly with higher doses used for shingles treatment.
Serious side effects are rare but worth knowing about. Confusion, agitation, or difficulty speaking can signal that the drug is affecting the central nervous system, which is more likely in older adults or people with kidney impairment. Any significant decrease in urination, blood in the urine, or unusual bruising warrants prompt medical attention, as these can indicate kidney injury or a rare blood-related reaction. These serious effects are most associated with high doses and impaired kidney function, not standard dosing in otherwise healthy people.