What is the recommended dosing for Valtrex (valacyclovir) for the treatment of cold sores?

Valtrex Dosing for Cold Sores

For cold sores (herpes labialis), the recommended dose of Valtrex is 2 grams twice daily for 1 day, with doses taken 12 hours apart, initiated at the earliest symptom such as tingling, itching, or burning. 1

Standard Dosing Regimen

• Adults and adolescents ≥12 years: 2 grams twice daily for 1 day (total of 4 grams over 12 hours) 1
• The two doses should be separated by exactly 12 hours 1
• Treatment can be taken without regard to meals 1

Critical Timing for Maximum Effectiveness

• Initiate therapy at the very first symptom (tingling, itching, burning, or prodromal sensation) before any visible lesion appears 1, 2
• Early patient-initiated therapy may actually prevent lesion development entirely in some cases 2
• Delayed initiation significantly reduces treatment effectiveness 2
• Patients should be counseled to keep medication on hand and start immediately when symptoms begin 2

Evidence Supporting This Regimen

• This high-dose, short-duration regimen reduced median episode duration by 1.0 day compared to placebo (p=0.001) 3
• Mean episode duration was reduced by 1.1 days with the 1-day treatment 3
• Time to lesion healing and cessation of pain were significantly reduced compared to placebo 3
• The proportion of patients in whom lesion development was prevented or blocked increased by 6.4-8.5% compared to placebo 3
• This simple 1-day regimen offers superior convenience compared to topical therapies while maintaining safety and efficacy 3

Pediatric Considerations

• Children <12 years: Valtrex is not FDA-approved for cold sores in this age group 1
• For children ≥12 years, use the same adult dosing (2 grams twice daily for 1 day) 1

Renal Impairment Adjustments

• Creatinine clearance 30-49 mL/min: No dose reduction needed 1
• Creatinine clearance 10-29 mL/min: 1 gram every 24 hours (single dose only, do not exceed 1 day of treatment) 1
• Creatinine clearance <10 mL/min: 500 mg every 24 hours (single dose only) 1
• Hemodialysis patients: Administer the recommended dose after hemodialysis 1

Safety Profile

• Valacyclovir is generally well-tolerated with minimal adverse events 2
• Common side effects include headache (more common than placebo), nausea, and diarrhea 2
• No serious adverse events have been reported in clinical trials for cold sore treatment 2
• Antiviral resistance remains very low (<0.5% in immunocompetent hosts) and is not a concern for episodic treatment 2

Common Pitfalls to Avoid

• Do not delay treatment waiting for visible lesions—the prodromal phase is the optimal treatment window 2, 1
• Do not extend treatment beyond 1 day in immunocompetent patients with cold sores—the approved regimen is specifically 1 day only 1
• Do not confuse cold sore dosing with genital herpes or herpes zoster dosing, which require different regimens and durations 1
• Ensure patients understand this is a treatment dose, not a suppressive therapy dose 1