Acyclovir Dosing for Herpes Zoster
For herpes zoster (shingles), the recommended dose is acyclovir 800 mg orally five times daily for 7 to 10 days. 1
Standard Oral Dosing Regimen
- Acyclovir 800 mg orally every 4 hours (5 times daily) for 7-10 days is the FDA-approved and guideline-recommended dose for acute herpes zoster treatment 1
- This high-dose regimen (800 mg five times daily) is superior to lower doses (400 mg five times daily) and significantly alters the course of disease 2
- Treatment accelerates rash healing, reduces viral shedding, decreases new lesion formation, and shortens the duration of acute pain 2, 3
Impact on Post-Herpetic Neuralgia
- The 800 mg five times daily regimen reduces the incidence and duration of post-herpetic neuralgia, shortening pain duration from an average of 86 days to 49 days (p<0.001) 4
- Treatment reduces the weekly prevalence of pain by the fourth week and decreases chronic pain prevalence in months 2-3 3
- The effect on post-herpetic neuralgia is most significant when treatment is initiated within 72 hours of rash onset 5
Timing of Treatment Initiation
- Treatment must be started as early as possible, ideally within 72 hours of rash onset, for maximum benefit in preventing complications 5
- Early treatment significantly reduces the incidence and severity of common complications including dendritiform keratopathy, stromal keratitis, and uveitis in herpes zoster ophthalmicus 5
Severe Disease and Intravenous Therapy
- For severe disease, complications, or hospitalized patients, use acyclovir 5-10 mg/kg IV every 8 hours for 5-7 days or until clinical improvement 6
- IV therapy is indicated for disseminated infection, pneumonitis, hepatitis, or CNS complications 6
Special Populations: Immunocompromised Patients
- Immunocompromised patients require more aggressive therapy with higher doses or IV administration 6
- These patients may need prolonged treatment courses and potentially suppressive therapy with acyclovir 400 mg orally 3-5 times daily 6
Renal Dose Adjustments
- For creatinine clearance 10-25 mL/min: reduce to 800 mg every 8 hours 1
- For creatinine clearance 0-10 mL/min: reduce to 800 mg every 12 hours 1
- For hemodialysis patients, administer an additional dose after each dialysis session due to 60% decrease in plasma concentrations during a 6-hour dialysis period 1
Common Pitfalls to Avoid
- Never use topical acyclovir for herpes zoster—it is substantially less effective than oral therapy and should not be used 6
- Do not use the lower 400 mg five times daily dose, as studies show this regimen does not achieve statistical significance compared to placebo 2
- Acyclovir does not eradicate latent virus and does not prevent future recurrences 6
Alternative Agents with Superior Convenience
- Valacyclovir 1,000 mg three times daily for 7 days offers equivalent or superior efficacy with simpler dosing (three times daily versus five times daily) and accelerates pain resolution compared to acyclovir 7
- Valacyclovir reduces the proportion of patients with pain persisting for 6 months (19.3% versus 25.7% with acyclovir) 7