Antiviral — Topical (Herpes Simplex Keratitis) Pregnancy: Topical use — considered safe; minimal systemic absorption

Aciclovir Eye Ointment 3%

Brand names: Zovirax Ophthalmic, Aciclovir Eye Ointment

Adult dose

Dose: 1 cm strip (approximately 10 mm) five times daily

Route: Topical ophthalmic (into conjunctival sac)

Frequency: Five times daily (approximately every 4 hours during waking hours)

Max: 5 applications per day; continue for 3 days after healing

Treatment of herpes simplex keratitis (dendritic and geographic ulcers). Continue for 3 days after healing — minimum 14 days total. CRITICAL: never give topical corticosteroids if herpes simplex keratitis is suspected (catastrophic visual loss risk). Fluorescein examination mandatory before steroid prescription.

Paediatric dose

Route: Topical

Frequency: Five times daily

Max: Same as adult

Used in paediatric herpetic keratitis; neonatal herpes keratoconjunctivitis: systemic aciclovir IV also required

Dose adjustments

Renal

No systemic absorption from topical ophthalmic use — no adjustment required

Hepatic

No adjustment

Clinical pearls

Herpetic keratitis misdiagnosis as bacterial conjunctivitis: dendritic (branching) ulcers stained with fluorescein are pathognomonic of HSV keratitis — CRITICAL: giving topical steroids to a patient with HSV keratitis causes geographic ulceration, stromal melting, and permanent visual loss
Fluorescein examination BEFORE any steroid prescription: all patients with a red eye should have their cornea examined with fluorescein and blue light before topical steroids are prescribed in ANY setting — this single step prevents the most catastrophic steroid misuse outcome
Recurrent HSV keratitis: HEDS trial (NEJM 1998) — oral aciclovir 400 mg BD reduces recurrence by 41% in high-risk patients; prophylactic oral aciclovir is recommended for patients with ≥2 episodes per year
Stromal herpetic keratitis (immune-mediated): paradoxically requires topical steroids + antiviral cover — the immune stromal response to viral antigens is more damaging than the virus itself; ophthalmologist management only
Zoster ophthalmicus: oral aciclovir 800 mg five times daily for 7–10 days is the treatment; topical aciclovir ointment is adjunct if corneal involvement

Contraindications

Hypersensitivity to aciclovir or valaciclovir
Do not use if bacterial keratitis is the primary diagnosis — seek ophthalmology

Side effects

Local stinging and burning on application
Punctate corneal epithelial erosions (mild, transient)
Conjunctival hyperaemia
Blepharitis

Interactions

No clinically significant interactions with topical ophthalmic use

Monitoring

Fluorescein examination — healing at 5–7 days
Re-epithelialisation
Visual acuity

Reference: BNFc; BNF 90; HEDS Trial (NEJM 1998); RCOphth Herpetic Keratitis Guidelines; SPC Zovirax Ophthalmic. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways