What is the recommended dosage of Valtrex (valacyclovir) for treating herpes simplex virus (HSV) blisters?

Valacyclovir (Valtrex) Dosage for Herpes Blisters

For herpes simplex virus (HSV) blisters, the recommended dosage of Valtrex is 500 mg twice daily for 3 days for recurrent episodes, or 1 gram twice daily for 10 days for initial episodes. 1

Dosing Recommendations by Type of Herpes Infection

Genital Herpes

• Initial episode: 1 gram twice daily for 10 days 1
  • Most effective when started within 48 hours of symptom onset
• Recurrent episodes: 500 mg twice daily for 3 days 1
  • Start at first sign or symptom of an episode
• Suppressive therapy:
  • Normal immune function: 1 gram once daily 1
  • ≤9 recurrences per year: 500 mg once daily 1
  • HIV-infected patients (CD4+ ≥100 cells/mm³): 500 mg twice daily 1

Cold Sores (Herpes Labialis)

• Adults and children ≥12 years: 2 grams twice daily for 1 day (taken 12 hours apart) 1
• Start at earliest symptom (tingling, itching, or burning)

Herpes Zoster (Shingles)

• 1 gram three times daily for 7 days 1
• Start at earliest sign or symptom, most effective within 48 hours of rash onset

Administration Guidelines

• Valtrex may be taken with or without food 1
• Initiate treatment at the earliest symptoms for best results 1
• For recurrent episodes, start treatment at the first sign of recurrence 1

Special Populations

HIV-Infected Patients

• May require longer courses of therapy and closer monitoring 2
• For suppressive therapy: 500 mg twice daily 2

Renal Impairment

Dosage adjustments are necessary for patients with impaired renal function:

• For acyclovir (similar adjustments may apply to valacyclovir):
  • Creatinine clearance >25 mL/min: No adjustment
  • Creatinine clearance 10-25 mL/min: Reduce frequency
  • Creatinine clearance <10 mL/min: Further reduce frequency 2

Prevention of Transmission

• Avoid direct contact with active lesions 2
• Use latex condoms during sexual activity 2
• Consider daily suppressive therapy (500 mg once daily) for reducing transmission risk in patients with ≤9 recurrences per year 1

Common Pitfalls and Caveats

1. Delayed treatment: Efficacy decreases significantly if treatment is delayed beyond 48-72 hours after symptom onset
2. Inadequate duration: Complete the full course of medication even if symptoms improve
3. Hydration: Maintain adequate hydration while taking valacyclovir to prevent renal complications
4. Drug interactions: Inform your healthcare provider about all medications you are taking

Remember that treatment is most effective when initiated at the earliest signs of an outbreak. For patients with frequent recurrences (>6 per year), consider long-term suppressive therapy rather than episodic treatment.