Acyclovir Dosing for Zoster (Shingles)
For the treatment of herpes zoster (shingles), acyclovir should be administered at a dose of 800 mg orally five times daily for 7-10 days. 1, 2
Recommended Dosing Regimen
- First-line treatment: Acyclovir 800 mg orally 5 times daily for 7-10 days 2, 3
- Treatment should be initiated as soon as possible after symptom onset, ideally within 72 hours of rash appearance 3, 4
- For children: Acyclovir 20 mg/kg body weight orally per dose (maximum 800 mg/dose) 4 times daily for 7-10 days or until no new lesions appear for 48 hours 2
Alternative Antiviral Options
If acyclovir is not tolerated or available, alternative options include:
Valacyclovir: 1,000 mg orally 3 times daily for 7 days 5
- Offers simpler dosing schedule with comparable efficacy
- Better bioavailability than acyclovir (3-5 times higher)
Famciclovir: 500 mg orally 3 times daily for 7 days 6
- Approved for adults and adolescents with zoster
Special Populations
Severe Immunosuppression
- For patients with severe immune suppression (CDC immunologic category 3), intravenous acyclovir is recommended 2
Renal Impairment
- Dose adjustment required for creatinine clearance <50 mL/min 1
- Maintain adequate hydration during treatment to minimize nephrotoxicity risk
Ophthalmic Zoster (Zoster Ophthalmicus)
- Same dosing regimen applies, but involvement of an experienced ophthalmologist is strongly recommended 2
- For persistent or recalcitrant disease, oral antivirals at the standard dose are beneficial 2
Clinical Pearls and Pitfalls
- Timing matters: Initiating treatment within 72 hours of rash onset provides maximum benefit for reducing acute pain and preventing postherpetic neuralgia 3, 4
- Duration of therapy: Treatment should continue for 7-10 days or until no new lesions appear for 48 hours 2
- Pain management: Antiviral therapy reduces the duration of zoster-associated pain from an average of 86 days to 49 days 3
- Monitoring: Follow patients for resolution of skin lesions and pain; consider extended therapy if healing is incomplete after 10 days
- Common side effects: Gastrointestinal symptoms (nausea, vomiting, diarrhea) are the most common adverse effects 7
Treatment Algorithm
- Confirm diagnosis of herpes zoster
- Assess timing of rash onset (ideally <72 hours)
- Evaluate immune status of patient
- For immunocompetent patients: Start acyclovir 800 mg orally 5 times daily for 7-10 days
- For severely immunosuppressed patients: Consider IV acyclovir
- For ophthalmic involvement: Consult ophthalmology while initiating treatment
- Monitor for clinical response and consider extending therapy if healing is incomplete
Remember that early treatment is crucial for reducing pain, speeding healing, and preventing complications such as postherpetic neuralgia.