Valacyclovir Dosing for Herpes Zoster
For immunocompetent adults with herpes zoster, prescribe valacyclovir 1000 mg orally three times daily for 7 days, initiated within 72 hours of rash onset. 1
Standard Dosing for Immunocompetent Adults
- The CDC recommends valacyclovir 1000 mg every 8 hours (three times daily) for 7 days as the standard regimen for herpes zoster in immunocompetent patients. 1
- This dosing has been shown to accelerate resolution of zoster-associated pain and reduce postherpetic neuralgia duration compared to acyclovir, while maintaining a favorable safety profile. 2
- Treatment is most effective when initiated within 48-72 hours of symptom onset, though starting later may still provide benefit. 3
Alternative Dosing Consideration
- A twice-daily regimen of valacyclovir 1.5 g (1500 mg) twice daily for 7 days has demonstrated equivalent safety and efficacy to the three-times-daily regimen, and may improve patient compliance. 4
- However, the CDC-recommended three-times-daily dosing remains the guideline standard. 1
Immunocompromised Adults
For immunocompromised patients with herpes zoster, use valacyclovir 1 g three times daily for 7 days, which is as effective as higher doses. 5
- A double-blind study demonstrated that valacyclovir 1 g three times daily was equally safe and effective as 2 g three times daily in immunocompromised patients, with similar median times to full crusting (8 days) and equivalent reduction in zoster-associated pain. 5
- Critical warning: The CDC advises against valacyclovir doses of 8 grams per day in immunocompromised patients due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome. 3
- For severe disease with complications (disseminated infection, pneumonitis, hepatitis, or CNS involvement), use IV acyclovir 5-10 mg/kg every 8 hours for 5-7 days instead of oral valacyclovir. 3
Pediatric Patients (≥2 years and adolescents)
For adolescents who can tolerate adult dosing, the CDC recommends valacyclovir 1 gram three times daily for 7 days. 1
- For children <12 years who cannot receive valacyclovir, acyclovir remains the preferred alternative at 20 mg/kg orally four times daily (maximum 800 mg/dose). 1
- For severe VZV disease or acute retinal necrosis in children old enough for adult dosing, the CDC recommends initial IV acyclovir 10 mg/kg three times daily for 10-14 days, followed by valacyclovir 1 gram three times daily for 4-6 weeks. 1
Renal Impairment Dosing
Valacyclovir requires mandatory dose adjustment based on creatinine clearance in patients with impaired renal function. 1
- The National Kidney Foundation emphasizes that valacyclovir must be used with caution in patients with impaired renal clearance, with dose adjustment based on creatinine clearance. 1
- For cardiac patients with severe renal impairment who cannot tolerate adjusted oral dosing, IV acyclovir with appropriate dose reduction may be necessary. 1
Common Pitfalls to Avoid
- Do not delay treatment waiting for laboratory confirmation—initiate therapy based on clinical presentation within 72 hours of rash onset. 3
- Do not use topical antivirals alone for VZV conjunctivitis, as they have not been shown to be helpful as monotherapy. 6
- Ensure adequate hydration throughout treatment to minimize renal toxicity risk. 7
- The most common adverse events are nausea and headache, with similar safety profiles across dosing regimens. 4, 2