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Antiviral — Topical (Herpes Simplex Keratitis) Pregnancy: Fertility No studies have been performed to investigate the effect of topically ophthalmic use of aciclovir on fertility. There is no information on the effect of aciclovir on human female fertility. In a study of 20 male patients with normal sperm count, oral aciclovir administered at doses of up to 1g per day for up to six months has been shown to have no clinically significant effect on sperm count, motility or morphology. With the recommended use of Aciclovir Agepha , the systemic exposure of aciclovir is expected to be negligible and no risk is anticipated. Pregnancy A post-marketing aciclovir pregnancy registry has documented pregnancy outcomes in women exposed to aciclovir. The registry findings have not shown an increase in the number of birth defects described amongst aciclovir exposed subjects compared with the general population, and any birth defects showed no uniqueness or consistent pattern to suggest a common cause. Systemic administration of aciclovir in internationally accepted standard tests did not produce embryotoxic or teratogenic effects in rabbits, rats or mice. With the recommended use of Aciclovir Agepha no effects during pregnancy are anticipated since systemic exposure of aciclovir is expected to be negligible. When necessary, Aciclovir Agepha eye ointment can be used during pregnancy. Breast Feeding Limited data show that the drug does pass into breast milk following systemic administration. However, the dosage received by the nursing infant following maternal use of Aciclovir Agepha eye ointment would be insignificant. The use of Aciclovir Agepha eye ointment can be considered during breast feeding.

Aciclovir Eye Ointment 3%

Brand names: Zovirax Ophthalmic, Aciclovir Eye Ointment

Aciclovir eye ointment is a topical antiviral (a nucleoside analogue) used to treat herpes simplex keratitis affecting the eye.

Adult dose

Dose: Herpes simplex keratitis (the SPC's only indication): a 1cm ribbon of aciclovir 30 mg/g (3%) eye ointment placed inside the lower conjunctival sac five times a day (at approximately 4 hourly intervals); the treatment should continue for at least 3 days after the healing is complete
Route: Ocular - ointment placed inside the lower conjunctival sac (for ocular use only; not for injection or oral intake)
Frequency: Five times a day, at approximately 4 hourly intervals
Pinned product: Aciclovir Agepha 30 mg/g eye ointment (eMC product 12988); SPC section 2: "1 g ointment contains 30 mg aciclovir". SPC 4.2 verbatim: "Unless otherwise prescribed, a 1cm ribbon of ointment should be placed inside the lower conjunctival sac five times a day (at approximately 4 hourly intervals). The treatment should continue for at least 3 days after the healing is complete." Elderly (65 years and over): "No adjustment in dosage is required." SPC 4.4: "There is insufficient clinical data on the use of Aciclovir Agepha eye ointment for deep corneal defects and the combined use of Aciclovir Agepha eye ointment with topical corticosteroids." "In case of a bacterial coinfection, an additional antibiotic therapy must be carried out." Transient mild stinging immediately following application may occur. "Patients should avoid wearing contact lenses when using Aciclovir Agepha eye ointment." The SPC prints no maximum dose.

Paediatric dose

Route: Ocular - ointment placed inside the lower conjunctival sac
Frequency: As for adults: five times a day at approximately 4 hourly intervals
SPC 4.2 verbatim: "Paediatric population: As for adults". No age bands, lower age limit or per-kg figure are printed in the section retrieved - do not derive one.

Dose adjustments

Renal

No adjustment in dosage is required (SPC 4.2: "Use in people with impaired renal and liver function: No adjustment in dosage is required.").

Hepatic

No adjustment in dosage is required (SPC 4.2: "Use in people with impaired renal and liver function: No adjustment in dosage is required.").

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance or to any of the excipients listed in section 6.1
  • Hypersensitivity to Valaciclovir

Side effects

  • Eye disorders, very common: superficial punctate keratopathy (did not necessitate an early termination of therapy and healed without sequelae)
  • Eye disorders, uncommon: transient mild stinging or burning occurring immediately following application; conjunctivitis
  • Eye disorders, rare: blepharitis
  • Immune system disorders, very rare: immediate hypersensitivity reactions, including angioedema and urticaria

Interactions

  • No clinically significant interactions have been identified when applied topically (SPC 4.5)
  • Combined use with topical corticosteroids: insufficient clinical data (SPC 4.4)

Monitoring

  • Continue treatment for at least 3 days after healing is complete
  • Bacterial coinfection: an additional antibiotic therapy must be carried out
  • Superficial punctate keratopathy (very common) did not necessitate early termination of therapy and healed without sequelae

Clinical monograph

How it works

It is phosphorylated by viral thymidine kinase to its active triphosphate, which inhibits viral DNA polymerase and halts herpesvirus DNA replication.

Prescribing in practice

  • Confirm the diagnosis of herpes simplex keratitis before treatment, as topical corticosteroids given alone in active dendritic ulceration can cause sight-threatening worsening.
  • Apply into the conjunctival sac and continue for a short period after healing to reduce recurrence, as directed by current prescribing references.
  • Specialist ophthalmology input is advised, particularly for stromal involvement or treatment failure.

Monitoring

Monitor the corneal lesion with slit-lamp and fluorescein staining to confirm healing and detect resistance or recurrence.

Counselling the patient

  • Transient mild stinging or blurred vision after application is common and usually settles.
  • Do not wear contact lenses during an active infection or while on treatment.
  • Complete the full course and attend follow-up even once symptoms improve.

Evidence & guidelines

Topical aciclovir is an established first-line agent for herpes simplex epithelial keratitis in UK practice and is supported by the Herpetic Eye Disease Study evidence base.

Reference: HEDS Trial (NEJM 1998); RCOphth Herpetic Keratitis Guidelines; SPC Zovirax Ophthalmic; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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