Valtrex dosage: How much valacyclovir to take for common conditions

Valtrex (valacyclovir) is an antiviral many people use for cold sores, genital herpes, and shingles. The right dose depends on what you’re treating, whether it’s a first episode or a repeat, and your kidney function. Below you’ll find clear, practical dose ranges, timing tips, and safety notes you can show your doctor.

Common adult dosages

Genital herpes - first episode: 1 gram (1000 mg) twice a day for 7 to 10 days. For recurrent outbreaks: 1 gram twice a day for 5 days, or 500 mg twice a day for 3 days. For daily suppression if you have frequent recurrences: 500 mg to 1 gram once daily depending on how often outbreaks happen and your doctor’s advice.

Cold sores (herpes labialis): A common short-course option is 2 grams taken twice in one day (2 g now, then 2 g 12 hours later). That’s a one-day treatment aimed at shortening a cold sore episode when started early.

Shingles (herpes zoster): The typical adult dose is 1 gram three times a day for 7 days. Starting treatment within 72 hours of the rash appearing gives the best chance to reduce pain and speed healing.

Kidney adjustment and safety tips

Valtrex is cleared by the kidneys, so dose changes are needed if you have reduced kidney function. If you have mild to moderate kidney disease, your doctor will lower the dose or stretch out how often you take it. In severe kidney failure or for patients on dialysis, specific reduced doses apply and doctors usually give a supplemental dose after dialysis.

Drink enough water while taking Valtrex—staying hydrated helps reduce the small risk of kidney trouble. Common side effects include headache, nausea, and stomach upset. Rarely, people—especially older adults or those with kidney problems—may experience confusion or agitation. Tell your prescriber about other medicines you take, especially probenecid or drugs that affect the kidneys.

Pediatric and older adult notes: Children’s doses vary by age and weight; valacyclovir is approved for some pediatric uses—check with a pediatrician. Older adults often need lower doses because kidneys work less well with age. If you take other antivirals or immunosuppressants, coordinate timing with your specialist. Keep an up-to-date med list with every clinic visit.

If you’re pregnant, breastfeeding, or planning pregnancy, talk to your clinician—many providers still use valacyclovir when benefits outweigh risks, but it’s a shared decision. Don’t change your dose or stop taking Valtrex suddenly without asking your doctor.

Practical tips: start treatment as soon as symptoms appear for best effect; keep a small travel supply if you get frequent recurrences; store tablets at room temperature and keep them away from kids. If you miss a dose, take it as soon as you remember unless it’s close to the next dose—then skip the missed one.

This page is a quick dosing overview, not a prescription. For exact dosing that fits your health, check with a healthcare professional or pharmacist before starting Valtrex. Ask questions often.