Valacyclovir Dosing for Acute Cold Sores
For acute cold sores (herpes labialis), the recommended dose of Valtrex is 2 grams twice daily for 1 day, with doses taken 12 hours apart. 1
Dosing Regimen
- The FDA-approved regimen is 2 grams BID for a single day (total of 2 doses) 1
- The two doses should be separated by 12 hours 1
- This high-dose, short-duration regimen is specifically designed for cold sores and differs from genital herpes dosing 1
Critical Timing Considerations
Therapy must be initiated at the earliest symptom of a cold sore (tingling, itching, or burning) for maximum effectiveness 1
- Early initiation is crucial—patient-initiated episodic therapy at first symptoms may even prevent lesion development in some cases 2
- Delayed initiation significantly reduces effectiveness 2
- Treatment started during prodrome or within 1 day of lesion onset provides the greatest benefit 3
Clinical Efficacy
The 1-day regimen demonstrates robust clinical benefits:
- Reduces median episode duration by 1.0 day compared to placebo (p=0.001) 3
- Significantly reduces time to lesion healing 3
- Decreases time to cessation of pain and discomfort 3
- Increases the proportion of patients in whom lesion development is prevented or blocked by 6.4% 3
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
- Adverse effects are similar across treatment groups 3
Special Populations
- Pediatric patients ≥12 years: Same dosing as adults (2 grams BID for 1 day) 1
- Renal impairment: Dose adjustment may be required 2
- Pregnancy: Safety not fully established; registry available for reporting exposures 4
Common Pitfall to Avoid
Do not confuse cold sore dosing with genital herpes dosing—genital herpes recurrences use 500 mg BID for 3 days, which is a completely different regimen 1. The cold sore regimen uses much higher doses (2 grams) but for a shorter duration (1 day only).