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Natamycin (Monograph)

Brand name: Natacyn
Drug class: Antifungals
ATC class: S01AA10
VA class: OP210
CAS number: 7681-93-8

Medically reviewed by on Jul 13, 2023. Written by ASHP.


Antifungal; tetraene polyene.

Uses for Natamycin

Fungal Ophthalmic Infections

Topical treatment of blepharitis, conjunctivitis, and keratitis caused by susceptible fungi, including keratitis caused by Fusarium solani.

Efficacy not established for use as a single agent for treatment of fungal endophthalmitis.

Use clinical diagnosis, laboratory diagnosis by smear and culture of corneal scrapings, and drug response to guide initial and continued therapy of fungal keratitis. Whenever possible, use in vitro susceptibility testing to confirm that causative organism is susceptible to natamycin.

Natamycin Dosage and Administration


Ophthalmic Administration

Apply 5% ophthalmic suspension topically to the eye.

For topical ophthalmic use only; do not inject directly into eye.

To avoid contaminating the ophthalmic suspension, do not allow tip of dispensing dropper to touch any surface.

Shake suspension well prior to each use.



Fungal Ophthalmic Infections
Fungal Blepharitis or Conjunctivitis

Instill 1 drop of 5% ophthalmic suspension into conjunctival sac of affected eye(s) 4–6 times daily.

Fungal Keratitis

Instill 1 drop of 5% ophthalmic suspension into conjunctival sac of affected eye(s) every 1–2 hours. After 3–4 days, may decrease frequency to 1 drop 6–8 times daily; in many cases, frequency may be gradually decreased every 4–7 days.

If no signs of improvement after 7–10 days of topical therapy, infection may be caused by pathogens not susceptible to natamycin; base continued therapy on clinical reevaluation and additional laboratory studies.

If evidence of improvement, continue topical therapy for 14–21 days or until there are no signs or symptoms of active fungal keratitis.

Special Populations

No special populations dosage recommendations.

Cautions for Natamycin



Sensitivity Reactions


Allergic reactions reported.

Administration Precautions

For topical ophthalmic use only; not for injection into the eye.

Do not wear contact lenses if any signs or symptoms of fungal blepharitis, conjunctivitis, or keratitis are present.

Specific Populations


Animal reproduction studies not performed to evaluate whether natamycin can cause fetal harm or affect reproduction capacity.

Use during pregnancy only if clearly needed.


Not known whether distributed into milk.

Use with caution in nursing women.

Pediatric Use

Safety and efficacy not established in pediatric patients.

Geriatric Use

No overall differences in safety and efficacy relative to younger adults.

Common Adverse Effects

Allergic reaction, change in vision, chest pain, corneal opacity, dyspnea, eye discomfort, eye edema, eye hyperemia, eye irritation or pain, foreign body sensation, paresthesia, tearing.

No formal drug interaction studies using natamycin 5% ophthalmic suspension.

Natamycin Pharmacokinetics



Systemic absorption not expected following topical application to the eye.

Following topical application of natamycin 5% ophthalmic suspension to the eye, the drug adheres to cornea in areas of epithelial ulceration and is retained in conjunctival fornices. Effective natamycin concentrations are attained within corneal stroma, but not in intraocular fluid.



Not known whether natamycin is distributed into milk.





2–24°C; do not freeze.

Protect from light and excessive heat.

Actions and Spectrum

Advice to Patients


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.



Dosage Forms


Brand Names







AHFS DI Essentials™. © Copyright 2024, Selected Revisions July 23, 2018. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

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