Is natamycin FDA approved? Understanding its dual regulatory status

October 8, 2025 •

4 min read

First approved by the FDA as a topical ophthalmic medication in 1978, natamycin has a complex regulatory history. To determine whether is natamycin FDA approved, one must consider its distinct applications in both medical treatment and food preservation.

Quick Summary

Natamycin holds separate FDA approvals for its use as a prescription eye drop (Natacyn) for fungal infections and as a food preservative (E235) on certain products. Different regulations apply depending on the intended application.

Key Points

Dual FDA Approval: Natamycin is FDA-approved for two distinct uses: as a prescription eye medication and as a food preservative.
Medical Application: It is available as the prescription drug Natacyn® (natamycin ophthalmic suspension) for treating fungal eye infections like keratitis and conjunctivitis.
Food Preservation: Natamycin is approved as a direct food additive (E235) under FDA regulations for inhibiting mold and yeast in certain foods, primarily cheese and dairy products.
Prescription-only Drug: Medically, Natacyn is a prescription-only item, not available over-the-counter.
Poor Systemic Absorption: In both topical eye use and food consumption, natamycin has poor absorption into the body, which minimizes safety risks and impact on antimicrobial resistance.
Mechanism of Action: Natamycin works by binding to ergosterol, a key component of fungal cell membranes, leading to cell disruption and death.

Natamycin’s Distinct FDA Approvals

Natamycin, also known as pimaricin, is a polyene macrolide antibiotic produced by the bacterium Streptomyces natalensis. Its potent antifungal properties have made it valuable in two very different fields, each requiring a separate approval process from the U.S. Food and Drug Administration (FDA). The FDA regulates medications for therapeutic use differently than food additives, leading to natamycin's dual status.

Medical Use: The Drug Approval Process

As a prescription medication, natamycin is marketed under the brand name Natacyn® and is available as a 5% ophthalmic suspension for topical application to the eyes. This particular formulation was approved by the FDA in 1978. It is the only FDA-approved topical antifungal eye drop on the market and is considered the gold standard for treating specific fungal eye infections.

The approval for Natacyn is based on its proven safety and effectiveness in treating several fungal conditions affecting the outer eye. This includes:

Fungal blepharitis: Inflammation of the eyelid.
Fungal conjunctivitis: Inflammation of the conjunctiva, the membrane lining the eyelid and eye surface.
Fungal keratitis: An infection of the cornea, which can be particularly severe, especially when caused by organisms like Fusarium solani.

When applied as eye drops, natamycin works by binding to sterols in the fungal cell membrane, disrupting its function and ultimately killing the fungal cells. The drug has poor systemic absorption, meaning it does not get into the bloodstream in significant amounts when used topically, which is an important safety consideration for its FDA approval.

Food Additive Use: GRAS Status and Specific Applications

Natamycin also has extensive approval for use as a natural food preservative, designated with the E number E235. The FDA permits its direct addition to food intended for human consumption under 21 CFR 172.155, specifically for inhibiting mold and yeast growth on certain products. The FDA has also accepted a “Generally Recognized As Safe” (GRAS) notification for specific uses, such as in yogurt.

Its function in food science is to extend shelf life and prevent spoilage by targeting molds and yeasts without affecting the bacterial cultures crucial for fermented products like cheese. Applications in the US include:

Cheese: Approved as an antimycotic, with a limit of 20 milligrams per kilogram (20 ppm) in the finished product. It is applied to the surface of cheese, either in powdered form or via a spray/dip.
Yogurt: The FDA issued a “no questions” letter regarding its GRAS status for use as an antimycotic in yogurt at levels not exceeding 5 ppm.
Other Dairy: Use has been extended to non-standard identity cottage cheese, sour cream, and cream cheese.
Baked Goods: Permitted on the surface of some breads and in soft tortillas.

Comparing FDA-Approved Uses


Feature	Medical Use (Natacyn®)	Food Additive Use (E235)
Regulatory Body	FDA's Center for Drug Evaluation and Research (CDER)	FDA's Center for Food Safety and Applied Nutrition (CFSAN)
Purpose	To treat existing fungal infections of the eye.	To prevent spoilage by inhibiting mold and yeast growth.
Administration	Topical ophthalmic application (eye drops).	Applied to the surface via dipping, spraying, or direct addition.
Dosage Form	5% ophthalmic suspension.	Crystalline powder or liquid solution.
Regulatory Status	Approved New Drug Application (NDA).	Permitted as a direct food additive under 21 CFR 172.155 and has GRAS status for some uses.
Requires Prescription	Yes, it is a prescription-only drug.	No, it is used in food manufacturing.

The Importance of Context in FDA Approval

The differing FDA approval pathways for natamycin highlight how regulatory bodies assess a substance based on its intended application. What is safe and effective as a topical eye drop is evaluated differently than a preservative added to food. Key differences include the route of administration, the required dosage, and the potential for systemic absorption. The FDA’s rigorous standards ensure that the appropriate safety and efficacy profile is established for each specific use. Concerns over antimicrobial resistance from food applications were addressed during the review process, noting natamycin's poor absorption and that low-level food use poses minimal risk to medical applications.

Conclusion

In summary, the question "Is natamycin FDA approved?" has a nuanced answer: Yes, it is, but for very specific and distinct applications. Natamycin is FDA-approved as the topical ophthalmic drug Natacyn®, used to treat fungal eye infections. Separately, it is approved as a food additive (E235) and has GRAS status for use in certain dairy products to prevent mold and yeast growth. This dual regulatory status reflects its versatility as an antifungal agent, with strict regulations in place to ensure safety for both pharmaceutical and food applications. Both approvals underscore the substance's efficacy and safety when used according to its defined purpose.

Learn more about natamycin's regulatory status on the FDA website.

Frequently Asked Questions

Yes, the active ingredient is the same, but they are different products regulated under different standards. Natacyn is a prescription ophthalmic drug, whereas food-grade natamycin is a preservative.

The FDA has approved natamycin for use as a preservative on certain dairy products, including cheese (up to 20 ppm) and yogurt (up to 5 ppm). It is also approved for use on certain other non-standard dairy items and some bakery products.

Yes, natamycin is considered a natural antimicrobial. It is produced through the fermentation of the bacterium Streptomyces natalensis and is widely used as a preservative in the food industry.

According to the FDA review, the risk of resistance from food-use natamycin is considered minimal. The substance is poorly absorbed by the body, and its exposure levels from food are very low, limiting the chances of developing clinically relevant resistance.

Yes, natamycin is a type of antibiotic, specifically a polyene macrolide antibiotic with potent antifungal properties. However, it is not effective against bacteria or viruses.

Natamycin is added to certain food products as a preservative to inhibit the growth of yeasts and molds, thereby extending the product's shelf life and preventing spoilage.

Natacyn is classified as Pregnancy Category C by the FDA, which means the risk to the fetus cannot be ruled out. Pregnant women should consult their doctor before using this medication.