Natamycin 5% Eye Drops

How it works

Natamycin binds ergosterol in the fungal cell membrane, disrupting membrane integrity and causing leakage of cellular contents and fungal cell death.

Prescribing in practice

• Suspected microbial keratitis is a sight-threatening emergency that should be managed under specialist ophthalmology supervision with corneal scrapes for microscopy and culture before or alongside starting treatment.
• Penetration into the cornea is limited and poor for deep or intraocular fungal disease, so it is most effective for surface and anterior corneal infection and may need to be combined with or switched to systemic or other antifungals.
• Shake the suspension well and continue for the full course directed, as fungal keratitis typically requires prolonged treatment with frequent early dosing.

Monitoring

Monitor by repeated slit-lamp examination of the corneal infiltrate and epithelial healing to confirm clinical response.

Counselling the patient

• Use the drops exactly as frequently as directed, including overnight if instructed early in treatment.
• Do not wear contact lenses while you have the infection or are using the drops.
• Attend all follow-up appointments, as fungal eye infections heal slowly and need close review.

Evidence & guidelines

Natamycin is an established first-line topical antifungal for filamentous fungal keratitis, supported by comparative trial evidence (the MUTT studies) favouring it for Fusarium keratitis.