What Is Natacyn? Uses, Dosage, and What You Need to Know in 2026

Natacyn Is the Only FDA-Approved Antifungal Eye Drop in the U.S.

Natacyn (Natamycin 5% ophthalmic suspension) is an antifungal eye drop used to treat fungal infections of the eye, including fungal keratitis, conjunctivitis, and blepharitis. It is the only FDA-approved topical ophthalmic antifungal available in the United States, making it the standard of care for these conditions.

Whether you've just been prescribed Natacyn or you're researching it for a loved one, this guide covers everything you need to know — from what it treats to how much it costs.

What Is Natacyn?

Here are the basics:

• Brand name: Natacyn
• Generic name: Natamycin (also known as Pimaricin)
• Drug class: Polyene antifungal (tetraene polyene antibiotic)
• Manufacturer: Alcon Laboratories, Inc.
• FDA-approved: Yes — it is the sole FDA-approved ophthalmic antifungal in the U.S.
• Controlled substance: No
• Generic available: No FDA-approved generic exists in the U.S.
• Formulation: 5% ophthalmic suspension (50 mg/mL) in a 15 mL amber glass bottle

Natacyn works by binding to sterol components in fungal cell membranes, disrupting membrane integrity and killing the fungus. It is predominantly fungicidal, meaning it kills fungi rather than just stopping their growth.

What Is Natacyn Used For?

Natacyn is FDA-approved for the treatment of:

• Fungal keratitis — An infection of the cornea (the clear front surface of the eye) caused by fungi. This is the most common and most serious indication. Fusarium solani keratitis is specifically mentioned in the labeling.
• Fungal conjunctivitis — A fungal infection of the conjunctiva (the thin membrane covering the white of the eye and inner eyelids).
• Fungal blepharitis — A fungal infection of the eyelids.

Natacyn is also sometimes used off-label for:

• Fungal endophthalmitis (though its effectiveness as a single agent has not been established for this condition)
• Ocular infections caused by Candida, Aspergillus, Cephalosporium, and Penicillium species

Fungal eye infections are relatively uncommon but serious. They most often occur after eye trauma involving plant material or soil, in contact lens wearers, or in people with weakened immune systems.

How Is Natacyn Taken?

Natacyn is applied as eye drops directly into the affected eye. Here's what the typical treatment looks like:

For Fungal Keratitis

1. Shake the bottle well before each use
2. Initial dosing: Instill 1 drop in the affected eye every 1-2 hours during waking hours
3. After 3-4 days: Reduce to 1 drop 6-8 times daily
4. Duration: Continue for 14-21 days or until the infection resolves
5. Tapering: Gradually reduce dosage at 4-7 day intervals

For Fungal Blepharitis or Conjunctivitis

• Instill 1 drop in the affected eye 4-6 times daily

Important Tips

• Always shake the bottle before using — Natacyn is a suspension, not a clear solution
• Don't touch the tip of the bottle to your eye or any surface
• If using other eye drops, wait at least 5 minutes between medications
• Complete the full course of treatment even if your eye feels better
• Don't wear contact lenses during treatment

For details on side effects to watch for during treatment, see our dedicated side effects guide.

Who Should Not Take Natacyn?

Natacyn should not be used by anyone with a known hypersensitivity to Natamycin or any component of the formulation.

Special caution is advised for:

• Pregnant women — Natacyn is Pregnancy Category C. No animal reproduction studies have been done. Use only if the benefit clearly outweighs the risk.
• Breastfeeding mothers — It's unknown whether Natamycin passes into breast milk. Discuss risks with your doctor.
• Children — Safety and effectiveness have not been established in pediatric patients, though it may be prescribed off-label when needed.

There are no significant drug interactions with Natacyn, though you should avoid using other topical eye medications concurrently unless directed by your doctor.

How Much Does Natacyn Cost?

Natacyn is an expensive medication, primarily because it's a single-source brand product with no generic competition:

• Cash price: Approximately $400-$700 for a 15 mL bottle
• Insurance: Coverage varies. Natacyn often requires prior authorization due to its specialty status. It may be covered under your medical benefit (if administered in a clinical setting) rather than your pharmacy benefit.
• No generic: There is no FDA-approved generic Natamycin ophthalmic product in the U.S., which keeps prices high.

If cost is a barrier, explore our guide on how to save money on Natacyn, including patient assistance programs and discount options. Alcon may offer assistance for eligible uninsured or underinsured patients — contact them at 1-800-757-9195.

Finding Natacyn

Because Natacyn is a specialty medication with limited distribution, finding it at a regular pharmacy can be challenging. Many retail pharmacies don't stock it. Your best options include:

• Your ophthalmologist's office dispensary
• Specialty pharmacies
• Hospital pharmacies
• Medfinder — to search for pharmacies that have it in stock near you

For step-by-step guidance, see our articles on how to find Natacyn in stock and how to check pharmacy stock without calling.

Final Thoughts

Natacyn holds a unique position in medicine — it's the only FDA-approved antifungal eye drop in the U.S. If you've been prescribed it, you need it for a serious reason. Understanding what it is, how to use it correctly, and what to expect helps you get the most out of your treatment.

The two biggest hurdles patients face with Natacyn are finding it in stock and affording it. Medfinder can help with both. And if you have questions about how Natacyn compares to other options, check our guide on alternatives to Natacyn.