What is the recommended dose of aciclovir (antiviral medication) for treating herpes zoster (shingles)?

Recommended Aciclovir Dosage for Herpes Zoster

For herpes zoster (shingles) treatment in immunocompetent adults, the recommended dose of aciclovir is 800 mg orally 5 times daily for 7 days. 1

Oral Treatment Regimens

• For standard herpes zoster cases in immunocompetent patients, aciclovir 800 mg should be administered orally 5 times daily for 7 days 1
• Treatment should be initiated as soon as possible, ideally within 72 hours of rash onset for maximum efficacy 1
• The frequent dosing schedule is necessary due to aciclovir's limited oral bioavailability 2

Special Populations and Situations

Severe Disease Requiring Hospitalization

• For patients with severe disease or complications requiring hospitalization (e.g., disseminated infection):
  • Intravenous aciclovir 5-10 mg/kg body weight every 8 hours for 5-7 days or until clinical resolution 3
  • This is particularly important for immunocompromised patients with zoster infections 4

Immunocompromised Patients

• For immunocompromised patients with zoster infections, a higher dose may be required:
  • Intravenous aciclovir at 500 mg/m² every 8 hours for 7 days has shown superiority over placebo in reducing cutaneous and visceral dissemination 4

Clinical Considerations

• Aciclovir treatment speeds rash healing, decreases pain, and reduces ocular complications in herpes zoster 2
• Starting treatment within 72 hours of rash onset is traditionally recommended, though some evidence suggests benefit may still exist with later initiation 5
• Aciclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after discontinuation 3

Alternative Treatment Options

• Valaciclovir (the prodrug of aciclovir) offers simplified dosing with better bioavailability:
  • Valaciclovir 1000 mg three times daily for 7 days has been shown to be at least as effective as aciclovir 800 mg five times daily 2, 6
  • Valaciclovir significantly accelerates the resolution of herpes zoster-associated pain compared to aciclovir 6
• Famciclovir is another alternative with less frequent dosing requirements:
  • Famciclovir 250 mg three times daily, 500 mg twice daily, or 750 mg once daily for 7 days shows comparable efficacy to aciclovir for cutaneous healing 7

Common Pitfalls and Caveats

• The limited oral bioavailability of aciclovir necessitates the frequent (5 times daily) dosing schedule, which may affect patient adherence 2
• Delayed treatment initiation (beyond 72 hours after rash onset) may reduce therapeutic efficacy, though some benefit may still be observed 5
• Patients should be monitored for potential adverse effects, with nausea and headache being the most commonly reported 5
• For patients who may struggle with the five-times-daily dosing regimen, consider newer antivirals with simplified dosing schedules (valaciclovir or famciclovir) 2, 7, 6