What is Natamycin: Uses, Dosage, Side Effects and More

Natamycin is an antifungal eye drop medication that treats serious fungal infections of the eye. It works by stopping fungal growth and is often the first choice when fungi threaten your vision. While fungal eye infections are uncommon, they can be serious and require prompt medical attention with specialized treatment like natamycin.

What is Natamycin?

Natamycin is a prescription antifungal medication specifically designed for eye infections. It belongs to a class of drugs called polyene antifungals, which means it targets the cell walls of fungi to stop their growth. This medication comes as eye drops and is one of the few antifungal treatments approved specifically for ophthalmic use.

The medication was originally derived from a soil bacteria and has been used safely for decades to treat fungal eye infections. It's particularly effective against yeast and mold infections that can affect the cornea and other parts of the eye. Your doctor will typically prescribe natamycin when they suspect or confirm a fungal cause for your eye infection.

What is Natamycin Used For?

Natamycin treats fungal infections of the eye, particularly those affecting the cornea (the clear front surface of your eye). These infections, called fungal keratitis, can occur when fungi enter the eye through an injury, contact lens use, or other means. The medication is specifically designed to target these stubborn infections that don't respond to bacterial treatments.

Your doctor might prescribe natamycin if you have symptoms like severe eye pain, blurred vision, light sensitivity, or discharge that doesn't improve with regular antibiotic drops. Fungal eye infections are more common in people who work outdoors, use contact lenses, or have had eye injuries involving plant material or soil.

The medication is also sometimes used for other fungal infections of the eye surface, including those affecting the conjunctiva (the thin membrane covering the white of your eye). However, corneal infections remain the most common reason for prescribing this medication.

How Does Natamycin Work?

Natamycin works by binding to a specific component in fungal cell walls called ergosterol. This binding disrupts the fungal cell membrane, causing the fungi to leak essential contents and eventually die. Think of it as creating holes in the fungal cells' protective barrier, which stops them from surviving and multiplying.

This medication is considered a moderate-strength antifungal that's specifically effective against the types of fungi that commonly infect eyes. Unlike some antifungal medications that work throughout the body, natamycin is designed to work locally in the eye tissue where the infection occurs.

The drops penetrate well into the corneal tissue, which is crucial since many fungal eye infections occur deep within this clear layer. This targeted action helps clear the infection while minimizing effects on the rest of your body.

How Should I Take Natamycin?

Take natamycin exactly as your doctor prescribes, typically as one drop in the affected eye every 1-2 hours initially. The frequency usually decreases as your infection improves, but this can take several weeks. Always wash your hands thoroughly before applying the drops and avoid touching the dropper tip to your eye or any surface.

You can take natamycin with or without food since it's applied directly to the eye. However, if you use other eye medications, space them at least 5-10 minutes apart to prevent one medication from washing out the other. Apply natamycin first if you're using multiple eye drops.

Shake the bottle gently before each use, as natamycin can settle at the bottom. Tilt your head back, pull down your lower eyelid to create a small pocket, and squeeze one drop into this space. Close your eye gently for 1-2 minutes to help the medication spread evenly across the eye surface.

Don't wear contact lenses while using natamycin unless your doctor specifically says it's okay. The infection itself and the medication can both affect how contacts fit and feel, and contacts might interfere with the medication's effectiveness.

How Long Should I Take Natamycin For?

Most people need to use natamycin for 2-4 weeks, though some infections may require longer treatment. Your doctor will determine the exact duration based on how your infection responds and may adjust the schedule as you improve. It's crucial to complete the full course even if your symptoms improve earlier.

Fungal infections typically take longer to clear than bacterial infections, so patience is important. You might start noticing improvement within a few days, but complete healing can take several weeks. Your doctor will want to see you regularly during treatment to monitor your progress and adjust the medication if needed.

Never stop using natamycin early, even if your eye feels better. Stopping too soon can allow the infection to return, potentially in a more resistant form. If you're not seeing improvement after a week or if your symptoms worsen, contact your doctor promptly for reassessment.

What Are the Side Effects of Natamycin?

Most people tolerate natamycin well, but some side effects can occur. The most common side effects are mild and affect the eye directly where you apply the drops. These temporary effects usually improve as your body adjusts to the medication.

Here are the side effects you might experience, starting with the most common ones:

• Temporary stinging or burning when you first apply the drops
• Mild eye irritation or redness
• Blurred vision for a few minutes after application
• Increased tearing or watery eyes
• Feeling like something is in your eye
• Light sensitivity
• Mild swelling of the eyelid

These common side effects typically last only a few minutes after applying the drops and shouldn't interfere with your daily activities. However, if they persist or worsen, let your doctor know during your next visit.

Less common but more serious side effects can occur, though they're rare. Contact your doctor immediately if you experience severe eye pain that worsens, significant vision changes, signs of allergic reaction like facial swelling, or any discharge that increases rather than decreases with treatment.

Some people may develop increased sensitivity to the medication over time, leading to more pronounced irritation. This is uncommon but worth monitoring, especially if you notice your eyes becoming more uncomfortable rather than less so as treatment continues.

Who Should Not Take Natamycin?

Most people can safely use natamycin, but certain individuals should avoid it or use it with extra caution. The main concern is allergic reactions, which can occur in people sensitive to natamycin or similar antifungal medications. Your doctor will review your medical history before prescribing this medication.

People who should be cautious or avoid natamycin include those with known allergies to polyene antifungals, individuals with certain autoimmune conditions affecting the eyes, and those taking specific medications that might interact with fungal treatments. Pregnant and breastfeeding women should discuss the risks and benefits with their doctor.

If you have a history of severe allergic reactions to medications, make sure your doctor knows before starting natamycin. While serious allergic reactions are rare, they can occur and require immediate medical attention.

Children can generally use natamycin safely, but the dosing may need adjustment based on age and weight. Your doctor will determine if this medication is appropriate for pediatric patients on a case-by-case basis.

Natamycin Brand Names

Natamycin is available under the brand name Natacyn in the United States. This is the most commonly prescribed formulation and comes as a 5% suspension (eye drops). Some countries may have different brand names or formulations, but the active ingredient remains the same.

Generic versions of natamycin may be available in some areas, though they're less common than the brand-name version. Whether you receive brand-name or generic natamycin, the medication works the same way and has similar effectiveness.

Always use the specific product your doctor prescribes, as different formulations might have slight variations in concentration or inactive ingredients. If you need to switch between brands or formulations, discuss this with your doctor first.

Natamycin Alternatives

Several other antifungal medications can treat fungal eye infections, though natamycin is often the first choice. Alternatives include voriconazole, amphotericin B, and fluconazole, which may be used in different formulations or for specific types of fungal infections. Your doctor will choose the best option based on your specific infection and medical history.

Some alternatives are available as eye drops, while others might be given as injections or oral medications for more severe infections. The choice depends on factors like the type of fungus causing your infection, how deep the infection penetrates, and how well you respond to initial treatment.

In some cases, your doctor might combine natamycin with other antifungal medications or use it alongside other treatments like surgical intervention for severe infections. The goal is always to clear the infection while preserving your vision and eye health.

Is Natamycin Better Than Other Antifungal Eye Medications?

Natamycin is often considered the gold standard for treating fungal eye infections because of its proven effectiveness and safety profile. It penetrates well into corneal tissue and has been used successfully for decades. However, whether it's "better" depends on your specific type of infection and individual circumstances.

Compared to other antifungal eye medications, natamycin has the advantage of being specifically approved for ophthalmic use and having extensive research supporting its effectiveness. It's particularly effective against filamentous fungi, which are common causes of fungal keratitis.

Your doctor will consider factors like the type of fungus identified, the severity of your infection, your medical history, and how you respond to treatment when choosing between natamycin and alternatives. Sometimes, what works best for one person may not be ideal for another.

The most important factor is starting appropriate antifungal treatment promptly, regardless of which specific medication is chosen. Delayed treatment can lead to more serious complications, so trust your doctor's expertise in selecting the right medication for your situation.