Valacyclovir Dosing for Herpes Outbreak
For an acute genital herpes outbreak, prescribe valacyclovir 500 mg twice daily for 3-5 days, initiated at the first sign of symptoms. 1
Dosing by Clinical Scenario
First Episode of Genital Herpes
- Valacyclovir 1 gram twice daily for 7-10 days 1, 2
- Most effective when started within 48 hours of symptom onset 1, 2
Recurrent Genital Herpes Episodes
- Valacyclovir 500 mg twice daily for 3-5 days 1, 2
- The 3-day regimen is equivalent to the 5-day course in efficacy 3
- Initiate during prodrome (tingling, itching, burning) or within 1 day of lesion onset for maximum effectiveness 1
Oral Herpes (Cold Sores)
- Valacyclovir 2 grams twice daily for 1 day, taken 12 hours apart 1, 4, 2
- This single-day regimen significantly reduces episode duration (median 4.0-5.0 days vs placebo) 4
- Start at earliest symptom (tingling, itching, burning) 4, 2
Special Populations
HIV-Infected Patients
- For recurrent episodes: 500 mg twice daily (same as immunocompetent patients) 1
- For suppressive therapy: 500 mg twice daily if CD4+ count ≥100 cells/mm³ 5, 2
Immunocompromised Patients
- Use standard dosing but monitor more closely 1, 4
- Avoid 8 grams per day due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome 5
Administration Details
- May be given without regard to meals 2
- Advise adequate hydration to minimize nephrotoxicity risk 5
- No dose adjustment needed if CrCl ≥30 mL/min 5
Treatment Failure Considerations
- If lesions persist after 7-10 days of appropriate therapy, consider HSV resistance 5
- All acyclovir-resistant strains are also resistant to valacyclovir 5
- For resistant HSV, IV foscarnet is the treatment of choice 5
Key Clinical Pearls
- Timing is critical: Valacyclovir reduces symptom duration, decreases pain, and accelerates healing when started early 1, 4
- The enhanced bioavailability of valacyclovir (3-5 fold better than acyclovir) allows for less frequent dosing 6, 7
- Treatment may potentially prevent lesion development when started during prodrome 4