What is the dosing for Valacyclovir (Valtrex) for herpes labialis (cold sores)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: May 6, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

For cold sores, the standard Valtrex (valacyclovir) dosing is 2 grams taken twice daily for one day, with doses separated by about 12 hours, although the provided evidence suggests a dose of 500 mg orally twice a day for 5 days or 1,000 mg orally once a day 1. However, it's essential to note that the provided evidence is from 1998 and may not reflect the most recent guidelines. The medication works by converting to acyclovir in the body, which inhibits viral DNA replication, preventing the herpes simplex virus from multiplying. Some key points to consider when taking Valtrex include:

  • Starting treatment at the earliest sign of a cold sore (tingling, burning, or itching) for maximum effectiveness
  • Taking the medication with plenty of water and maintaining good hydration throughout treatment
  • Potential dose adjustments for those with kidney problems
  • Common side effects, such as headache, nausea, and dizziness, which are usually mild and temporary It's also worth noting that for people with frequent outbreaks (more than 6 per year), a suppressive dose of 500 mg to 1 gram daily may be prescribed, as seen in the 1998 guidelines 1.

From the FDA Drug Label

The recommended dosage of VALTREX for treatment of cold sores is 2 grams twice daily for 1 day taken 12 hours apart. Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning). The recommended dosage of VALTREX for the treatment of cold sores in pediatric patients aged greater than or equal to 12 years is 2 grams twice daily for 1 day taken 12 hours apart. Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning).

The recommended dosing for cold sores is:

  • 2 grams twice daily for 1 day, taken 12 hours apart, for both adults and pediatric patients aged 12 years and older. Therapy should be initiated at the earliest symptom of a cold sore, such as tingling, itching, or burning 2 2.

From the Research

Valtrex Dosing for Cold Sores

  • Valtrex, also known as valacyclovir, is an oral antiviral agent approved for the therapy of herpes labialis (cold sores) 3.
  • The treatment of cold sores with valacyclovir has been shown to decrease the duration of lesion episodes and pain by approximately one day 4.
  • Valacyclovir is the only oral antiviral agent approved for a 3-day course in the episodic treatment of recurrent genital herpes, as well as the only antiviral drug approved for once daily dosing for suppressive therapy 3.
  • In the treatment of herpes zoster, valacyclovir is more effective than acyclovir and equally effective as famciclovir at hastening the healing of zoster-associated pain and postherpetic neuralgia (PHN) 3, 5.
  • The choice of dosing regimen for valacyclovir depends on the clinical characteristics and patient preference, and evidence-based dosing regimens should be selected 6.

Comparison with Other Antivirals

  • Valacyclovir appears to be somewhat better than famciclovir for suppression of genital herpes and associated shedding 7.
  • Famciclovir and valacyclovir have different intracellular pharmacokinetics, but the importance of these differences is unknown 5.
  • Valacyclovir and famciclovir appear to decrease time to resolution of pain compared with acyclovir in patients with herpes zoster infections 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Pharmacology of new antiherpes agents: famciclovir and valacyclovir.

Journal of the American Pharmaceutical Association (Washington, D.C. : 1996), 1997

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.