Acyclovir / valacyclovir (oral)
Orals / systemic · Rx
Trade namesZovirax (oral), Valtrex
Drug classAntiviral, systemic (adjunct to eye care)
StrengthAcyclovir 400 mg; valacyclovir 500 mg-1 g
AvailabilityRx
Mechanism of actionGuanosine analogs activated by viral thymidine kinase; inhibit viral DNA polymerase. Oral route achieves therapeutic corneal/anterior-chamber levels.
Indication / reason for useHSV epithelial and stromal keratitis, herpetic iritis; herpes zoster ophthalmicus; long-term prophylaxis of recurrent HSV keratitis (HEDS regimen).
Usual adult dosingHSV keratitis: aciclovir 400 mg 5×/day (or valaciclovir 500 mg TID) for 7-10 days. HZO: aciclovir 800 mg 5×/day or valaciclovir 1 g TID for 7-10 days, started within 72 h. Prophylaxis: aciclovir 400 mg BID.
PreservativeN/A (oral) , a preservative-free option exists
Contact lensesNo ocular product; lens restrictions relate to the keratitis itself.
Common / important adverse effectsNausea, headache; renal impairment with dehydration (ensure fluids); rare TTP/HUS with high-dose valaciclovir in immunocompromised.
Contraindications & cautionsDose-adjust in renal impairment.
Pregnancy / lactationAciclovir has extensive reassuring pregnancy data; preferred when systemic antiviral is needed.
Practice notesHEDS trial: 400 mg BID roughly halves the recurrence rate of HSV epithelial and stromal keratitis over 12 months.
Chair-side reference only. Dosing, contraindications and pregnancy guidance here are not exhaustive. Confirm against the current prescribing information and the patient’s full history before prescribing or advising.