Oral Acyclovir for Herpes Zoster (Shingles)
Yes, oral acyclovir is indicated and FDA-approved for the acute treatment of herpes zoster in adults, and should be initiated within 72 hours of rash onset to reduce pain severity, accelerate healing, and potentially decrease postherpetic neuralgia. 1, 2
Treatment Algorithm
Timing of Initiation
- Start treatment within 72 hours of rash onset for optimal efficacy in reducing acute pain, accelerating cutaneous healing, and preventing postherpetic neuralgia 2, 3
- Treatment initiated between 48-72 hours still provides significant benefit, though earlier is better 4
- Immunocompromised patients should receive antiviral therapy regardless of timing due to higher risk for disseminated infection 4
Standard Dosing for Immunocompetent Adults
- Acyclovir 800 mg orally five times daily for 7-10 days is the FDA-approved regimen 1, 5
- Continue treatment until all lesions have completely scabbed, not just for an arbitrary 7-day period 3, 4
- The 800 mg five times daily dose is superior to 400 mg five times daily and is the only effective oral dose 5
Alternative Oral Antivirals
- Valacyclovir 1000 mg three times daily for 7 days offers superior convenience with less frequent dosing and comparable or superior efficacy 6, 7
- Valacyclovir accelerates pain resolution compared to acyclovir (median 38 days vs 51 days) and reduces postherpetic neuralgia duration 6
- Famciclovir is also FDA-approved with similar efficacy when administered within 72 hours 2
Evidence Supporting Treatment
Clinical Benefits
- Acyclovir significantly shortens viral shedding, accelerates time to 50% scabbing and healing, and reduces new lesion formation 5
- Pain severity is significantly reduced during treatment (Days 3-10), correlating with decreased new lesion formation 5
- In elderly patients (≥50 years), acyclovir reduces pain during treatment and decreases the proportion with pain persisting at 6 months (19.3% vs 25.7% with placebo) 6, 8
Important Caveats
- Topical acyclovir is substantially less effective than systemic therapy and is not recommended 3
- The benefit in healthy young adults may be limited, as one study found no statistically significant difference in pain duration in this population, though this conflicts with FDA approval and guideline recommendations 9
- Treatment does not eradicate latent virus but controls acute symptoms and reduces complications 3
Special Populations Requiring Modified Approach
Immunocompromised Patients
- Intravenous acyclovir 10 mg/kg every 8 hours is recommended for disseminated or invasive herpes zoster 3
- Consider temporary reduction in immunosuppressive medications if clinically feasible 3
- Treatment duration extends beyond 7-10 days until complete clinical resolution 3
Complicated Disease
- Switch to IV acyclovir for multi-dermatomal involvement, CNS complications, or complicated ocular disease 3
- Monitor renal function closely during IV therapy with dose adjustments for renal impairment 3
Renal Impairment
- Dose adjustments are mandatory to prevent acute renal failure based on creatinine clearance 3
Common Pitfalls to Avoid
- Do not use the 400 mg five times daily dose - this regimen showed no significant benefit over placebo 5
- Do not stop at exactly 7 days if lesions are still forming or have not completely scabbed 3
- Do not delay treatment waiting for laboratory confirmation in typical presentations - clinical diagnosis is sufficient in immunocompetent patients 3
- Do not use short-course therapy designed for genital herpes (e.g., 400 mg TDS) - this is inadequate for VZV infection 3