What is the recommended dosing for Valtrex (valacyclovir) in various herpes infections?

Valacyclovir (Valtrex) Dosing Recommendations for Herpes Infections

The recommended dosing for Valtrex (valacyclovir) varies by indication, with 1 gram twice daily for 10 days for initial genital herpes episodes, 500 mg twice daily for 3 days for recurrent episodes, and 1 gram once daily for chronic suppressive therapy in patients with normal immune function. 1

Dosing by Indication

Genital Herpes

Initial Episode

• Dosage: 1 gram twice daily
• Duration: 10 days
• Timing: Most effective when started within 48 hours of symptom onset 1

Recurrent Episodes

• Dosage: 500 mg twice daily
• Duration: 3 days
• Timing: Start at first sign or symptom of an episode 1
• Alternative shorter regimen: A 3-day course is as effective as a 5-day course for episodic treatment 2

Suppressive Therapy

• For patients with normal immune function:

  • 1 gram once daily (standard dosing) 1
  • Alternative: 500 mg once daily (for patients with ≤9 recurrences per year) 1, 3

• For HIV-infected patients (CD4+ ≥100 cells/mm³):

  • 500 mg twice daily 1

• For reducing transmission:

  • 500 mg once daily (for source partner with ≤9 recurrences per year) 1

Cold Sores (Herpes Labialis)

• Dosage: 2 grams twice daily
• Duration: 1 day (taken 12 hours apart)
• Timing: Start at earliest symptom (tingling, itching, burning) 1

Herpes Zoster (Shingles)

• Dosage: 1 gram three times daily
• Duration: 7 days
• Timing: Start at earliest sign/symptom, most effective within 48 hours of rash onset 1

Special Populations

Pediatric Patients

• Cold sores (≥12 years): 2 grams twice daily for 1 day 1
• Chickenpox (2 to <18 years): 20 mg/kg three times daily for 5 days (maximum 1 gram three times daily) 1

Renal Impairment

Dose adjustments required based on creatinine clearance:

• CrCl ≥50 mL/min: No adjustment needed
• CrCl 30-49 mL/min: No adjustment needed
• CrCl 10-29 mL/min: 500 mg every 24 hours
• CrCl <10 mL/min: 500 mg every 24 hours 4

Efficacy Considerations

• Valacyclovir 500 mg once daily is less effective for patients with very frequent recurrences (≥10 episodes per year); these patients should receive 1 gram once daily or 500 mg twice daily 5, 3
• Daily suppressive therapy reduces herpes recurrences by ≥75% and decreases transmission risk to sexual partners by 48% overall 4
• Suppressive therapy reduces but does not eliminate asymptomatic viral shedding 5

Administration Guidelines

• Valtrex may be given without regard to meals 1
• For patients who cannot swallow tablets, an oral suspension can be prepared extemporaneously from 500 mg tablets 1
• Safety and efficacy have been documented for valacyclovir up to 1 year in immunocompetent patients 4

Common Pitfalls and Caveats

1. Timing matters: Treatment efficacy is maximized when started within 48 hours of symptom onset for both initial episodes and recurrences 1

2. Dosing frequency: For patients with ≥10 recurrences per year, once-daily 500 mg dosing is insufficient; use 1 gram once daily or 250 mg twice daily 3

3. Hydration: Ensure adequate hydration during treatment to prevent potential neurotoxicity, especially with higher doses 4

4. Monitoring: For immunocompromised patients on high-dose therapy, monitor for thrombotic microangiopathy-like syndrome 6

5. Duration of suppressive therapy: After 1 year of continuous suppressive therapy, consider discontinuation to reassess recurrence frequency, as recurrences may decrease over time 5