What is the recommended dose of Acyclovir (antiviral medication) for an immunocompetent adult with uncomplicated shingles?

Acyclovir Dosing for Shingles in Immunocompetent Adults

For uncomplicated shingles in immunocompetent adults, the recommended dose is acyclovir 800 mg orally five times daily for 7-10 days, initiated within 72 hours of rash onset. 1

Standard Dosing Regimen

• Acyclovir 800 mg orally every 4 hours (five times daily) for 7-10 days is the FDA-approved dose for acute herpes zoster treatment 1
• Treatment must be initiated within 72 hours of rash onset for optimal efficacy in reducing acute pain, accelerating lesion healing, and preventing postherpetic neuralgia 2
• The most benefit occurs when treatment begins within 48 hours of rash onset 3

Treatment Duration Considerations

• Continue antiviral therapy until all lesions have completely scabbed, not just for an arbitrary 7-day period 2
• Treatment should not be discontinued at exactly 7 days if lesions are still forming or have not completely scabbed 2
• The key clinical endpoint is complete scabbing of all lesions, which typically occurs within 7-10 days in immunocompetent patients 2

Alternative Antiviral Options

While acyclovir is effective, newer agents offer improved convenience:

• Valacyclovir 1000 mg orally three times daily for 7 days provides superior bioavailability and less frequent dosing, with demonstrated superiority in accelerating pain resolution (median 38 days vs 51 days with acyclovir) 4
• Famciclovir 500 mg orally three times daily for 7 days offers comparable efficacy to acyclovir with more convenient dosing and is the only oral antiviral proven to reduce postherpetic neuralgia duration 5, 6

Critical Dosing Pitfalls

• Do not use acyclovir 400 mg three times daily for shingles - this dose is only appropriate for HSV suppression, not varicella-zoster virus 2, 7
• Topical acyclovir is substantially less effective than systemic therapy and should not be used 2
• The five-times-daily dosing requirement for oral acyclovir (every 4 hours while awake) can be challenging for adherence 1

Renal Dose Adjustments

For patients with renal impairment, mandatory dose adjustments are required 1:

• Creatinine clearance >25 mL/min: 800 mg every 4 hours (5 times daily)
• Creatinine clearance 10-25 mL/min: 800 mg every 8 hours
• Creatinine clearance 0-10 mL/min: 800 mg every 12 hours
• Hemodialysis patients: Administer an additional dose after each dialysis session 1

When to Escalate to Intravenous Therapy

Switch to intravenous acyclovir 10 mg/kg every 8 hours for 2:

• Disseminated or multi-dermatomal herpes zoster
• Suspected CNS involvement or severe ophthalmic disease
• Immunocompromised patients with complicated disease
• Visceral organ involvement

Monitoring Requirements

• Monitor renal function closely during therapy, with dose adjustments as needed for renal impairment 2
• Ensure adequate hydration, as acyclovir is primarily renally excreted 7
• If lesions fail to begin resolving within 7-10 days, suspect acyclovir resistance and obtain viral culture with susceptibility testing 2