Acyclovir Dosing for Herpes Zoster Ophthalmicus
For herpes zoster ophthalmicus (HZO), treat with oral acyclovir 800 mg five times daily for 7 days, initiated within 72 hours of skin eruption onset for optimal outcomes. 1, 2
Oral Acyclovir Regimen
- Standard dose: Acyclovir 800 mg orally 5 times daily for 7 days is the established regimen for acute herpes zoster ophthalmicus 1, 2
- A 7-day course is sufficient and equally effective as 14-day treatment, with no significant differences in ocular complications or outcomes between durations 1
- Treatment should be initiated within 72 hours of skin eruption for maximum benefit, though treatment up to 7 days after onset still provides prophylactic benefit against ocular complications 3, 2
Intravenous Acyclovir for Severe Disease
- For severe complications requiring hospitalization (severe uveitis, iridocyclitis with hyphema, hemorrhagic glaucoma): Acyclovir 5-10 mg/kg IV every 8 hours 4, 5
- Duration of IV therapy should be extended beyond 7 days if active iridocyclitis persists, as standard 7-day courses may be insufficient for severe intraocular inflammation 5
- Continue IV treatment for 5-7 days or until clinical resolution is attained 4
Treatment Window and Efficacy
- Early treatment (within 72 hours) produces the greatest clinical response, reducing acute pain severity and accelerating resolution of dermatomal symptoms 2
- Treatment initiated within 72 hours significantly reduces ocular complications: late ocular inflammatory complications occur in only 29% of treated patients versus 50-71% in untreated patients 1
- Even delayed treatment (up to 7 days after onset) confers beneficial prophylactic effects against ocular complications including keratitis and uveitis 3
Expected Outcomes with Treatment
- Acyclovir significantly reduces the incidence and severity of the most common ocular complications: dendritiform keratopathy, stromal keratitis, and uveitis 2
- Active ocular disease at 6 months is significantly less common in acyclovir-treated patients (p = 0.01) 6
- Post-herpetic neuralgia occurs in only 13% of treated patients, with pain significantly less severe between 2-6 months post-treatment 1, 6
Critical Clinical Considerations
- Concomitant topical therapy: Consider adding ophthalmic 3% acyclovir ointment to oral therapy for comprehensive treatment 1
- Renal dosing: Exercise caution and adjust doses in patients with impaired renal clearance 7
- Follow-up: Monitor patients for at least 6 months, as late ocular inflammatory complications can develop despite treatment 1
Common Pitfalls to Avoid
- Do not extend oral acyclovir 800 mg 5 times daily beyond 7 days for uncomplicated cases, as longer duration provides no additional benefit 1
- Do not delay treatment waiting for "ideal" presentation—treatment up to 7 days after onset still provides benefit 3
- Do not discontinue IV therapy prematurely in severe cases with persistent iridocyclitis, as 7 days may be insufficient 5