Colistin (Polymyxin E) Eye Drops: Uses, Brands & Dosage

Colistin (Polymyxin E) is a powerful antibiotic used in eye drops or injections to treat severe, drug-resistant eye infections.

Drug class	Antibiotic (Polymyxin)
Type	Single
Forms	Fortified Eye Drop / IV
Common strength	Varies
Prescription status	Prescription (hospital use)

What Colistin (Polymyxin E) is used for

Colistin (Polymyxin E) is a strong antibiotic medicine primarily used to treat very serious eye infections that have not responded to other antibiotics. These infections are often caused by specific types of bacteria that are resistant to many common medicines. At Pristine Eye Hospitals, we use Colistin when other treatments might not be effective.

Multidrug-resistant (MDR) Keratitis: This is a severe infection of the cornea (the clear front part of your eye) that is resistant to multiple antibiotics.
Multidrug-resistant (MDR) Endophthalmitis: This is a very serious infection inside the eye, often affecting the vitreous (the jelly-like substance filling the eye) and retina, which can lead to significant vision loss if not treated aggressively.

Specifically, it is effective against certain types of bacteria like Pseudomonas and Acinetobacter that are known to cause difficult-to-treat infections.

How it works

Colistin (Polymyxin E) works by targeting the outer layer of the bacteria causing the infection. Think of bacteria as having a protective skin or wall. Colistin disrupts this outer layer, making it unstable and causing the bacteria to break down and die. This action helps to clear the infection from your eye.

How it’s used

Colistin (Polymyxin E) is a powerful medicine and is always administered under strict medical supervision in a hospital or clinic setting. It is never for self-use.

For Eye Drops:

When used as fortified eye drops, the medicine is specially prepared by the hospital pharmacy to a specific strength. You will be instructed on how to use these drops. Typically, for severe infections, these drops are given very frequently, often hourly, to ensure a high concentration of the medicine reaches the infected area. Your doctor or nurse will show you exactly how to instil the drops correctly. It is crucial to follow their instructions precisely regarding the frequency and number of drops.

For Intravenous (IV) Administration:

In some very severe cases, especially if the infection is deep inside the eye or widespread, Colistin may be given as an intravenous (IV) injection. This means the medicine is delivered directly into your bloodstream through a vein. The dosing for IV administration is carefully calculated by your doctor based on your specific condition and body weight, and it will be administered by trained medical staff according to a strict protocol.

It is very important to complete the full course of treatment as prescribed, even if your symptoms start to improve. Stopping the medicine too early can lead to the infection returning or becoming even more resistant to treatment.

Always follow your ophthalmologist’s exact instructions.

Brands in India

Hospital-prepared or not marketed as a retail brand in India.

Good to know

Prescription eye medicine — use only as directed by a qualified ophthalmologist. This page is for general education and is not a substitute for professional medical advice, diagnosis or a prescription. Do not self-medicate or reuse an old prescription. This is given only by specialists in a hospital or clinic setting and is never for self-use.

Precautions & side effects

Colistin (Polymyxin E) is a strong antibiotic and is used with careful consideration due to its potency. Here are some important precautions:

Reserved for Multidrug-Resistant Organisms: This medicine is specifically reserved for treating infections caused by bacteria that are resistant to many other antibiotics. This helps to ensure its effectiveness for the most challenging cases and prevents the development of further drug resistance.
Systemic Nephrotoxicity: When Colistin is given intravenously (into the bloodstream), there is a risk of affecting your kidneys (nephrotoxicity). Your doctor will closely monitor your kidney function through blood tests if you are receiving the IV form of this medicine. While the risk is lower with eye drops, your overall health will always be considered.
Hospital Use Only: Colistin is a prescription eye medicine and is only used as directed by a qualified ophthalmologist, typically within a hospital or specialist clinic setting. It is never for self-medication or for use outside of professional medical guidance.
No Self-Medication: Do not attempt to self-medicate or reuse an old prescription. This medicine requires specialist evaluation and preparation.
Allergies: Always inform your doctor if you have any known allergies to medicines, especially antibiotics.
Pregnancy and Breastfeeding: If you are pregnant, planning to become pregnant, or breastfeeding, discuss this with your doctor before starting any treatment.
Other Medications: Inform your doctor about all other medicines you are taking, including over-the-counter drugs, supplements, and herbal remedies, to avoid any potential interactions.

Your doctor will carefully weigh the benefits of using Colistin against any potential risks, especially given the severity of the infections it treats. Regular follow-up appointments are crucial to monitor your progress and manage any potential side effects.

Understanding Eye Infections Treated by Colistin

At Pristine Eye Hospitals, we understand that an eye infection can be concerning. Colistin (Polymyxin E) is a powerful medicine used for very specific and serious eye infections. The conditions it treats, such as keratitis and endophthalmitis, are not typical ‘pink eye’ infections. Keratitis is an inflammation or infection of the cornea, the clear, dome-shaped front surface of your eye that covers the iris and pupil. When this infection is severe and caused by bacteria resistant to many common antibiotics, it’s called multidrug-resistant (MDR) keratitis. This can be very serious and, if not treated effectively, can lead to scarring of the cornea and significant vision loss. Endophthalmitis is an even more severe infection that occurs inside the eye, affecting the vitreous (the jelly-like substance that fills the eye) and sometimes the retina. This condition is an ophthalmic emergency and requires immediate and aggressive treatment to preserve vision. The bacteria that cause these severe, resistant infections, like Pseudomonas and Acinetobacter, are particularly challenging to treat, which is why a potent antibiotic like Colistin is sometimes necessary. Our specialists at Pristine Eye Hospitals are highly experienced in diagnosing and managing these complex eye conditions, ensuring you receive the most appropriate and effective care.

Correct Use of Eye Drops and Ointments

While Colistin is typically administered by medical professionals or under very close supervision, understanding the general principles of using eye medicines correctly is always helpful. Proper technique ensures the medicine reaches your eye effectively and reduces the risk of contamination. Always wash your hands thoroughly with soap and water before touching your eyes or eye medicine. If you are instructed to instil drops yourself, tilt your head back or lie down. Gently pull down your lower eyelid to create a small pocket. Hold the dropper directly over your eye, being careful not to touch your eye, eyelid, or any other surface with the tip. Squeeze the bottle gently to release the prescribed number of drops into the pocket. Close your eye gently for a minute or two, without squeezing, to allow the medicine to absorb. If you need to use more than one type of eye drop, wait at least 5-10 minutes between different medications to prevent one from washing out the other. If you are using an eye ointment, apply a small ribbon of ointment into the same lower eyelid pocket. Close your eye and roll your eyeball around to spread the ointment. You might experience temporary blurred vision with ointments. Always use a clean tissue to blot any excess medicine from around your eye. Never share your eye medicine with anyone else, as this can spread infection.

Hygiene, Storage, and When to Seek Help

Maintaining good hygiene is paramount when dealing with eye infections. Always wash your hands before and after touching your eyes or applying eye medicine. Avoid rubbing your eyes, as this can worsen irritation or spread the infection. If you wear contact lenses, you will almost certainly be advised to stop wearing them during treatment for an eye infection. Always follow your doctor’s specific instructions regarding contact lens use. For storage, keep your eye medicine in a cool, dry place, away from direct sunlight and out of reach of children. Do not store eye drops in the refrigerator unless specifically instructed by your pharmacist or doctor. Check the expiry date on the medicine and discard any expired products. Fortified eye drops, like those containing Colistin, are specially prepared and have a limited shelf life; always adhere to the discard date provided by the hospital pharmacy. It is crucial to monitor your symptoms carefully. If your eye pain worsens, your vision decreases, you notice increased redness or discharge, or you develop any new or concerning symptoms, contact Pristine Eye Hospitals immediately. Do not wait for your next scheduled appointment. Early detection and intervention are key to managing eye infections effectively and preserving your vision. Remember, this page is for general education and is not a substitute for professional medical advice, diagnosis, or a prescription. Always consult with a qualified ophthalmologist for any eye concerns.

Frequently asked questions

What is Colistin (Polymyxin E) used for?

Colistin (Polymyxin E) is a powerful antibiotic used to treat very severe eye infections, specifically those caused by bacteria that are resistant to many other antibiotics. This includes serious infections of the cornea (keratitis) and inside the eye (endophthalmitis) caused by bacteria like Pseudomonas and Acinetobacter.

How does Colistin (Polymyxin E) work?

Colistin works by disrupting the outer protective layer of the bacteria. By damaging this outer membrane, it causes the bacteria to break down and die, helping to clear the infection from your eye.

What are the common Indian brands of Colistin (Polymyxin E)?

For systemic (IV) use, brands like Walcoli and Xylistin exist. However, for eye conditions, Colistin is typically used as a 'fortified topical hospital-prepared' eye drop. This means it is specially prepared by the hospital pharmacy for individual patient use and is not available as a standard retail eye drop brand.

How is Colistin (Polymyxin E) used for eye infections?

For eye infections, Colistin is typically used as fortified eye drops, which are often administered hourly for severe cases. In very serious situations, it may also be given intravenously (IV) as per medical protocol. It is always administered by specialists in a hospital or clinic setting and is never for self-use.

Do I need a prescription for Colistin (Polymyxin E)?

Yes, Colistin (Polymyxin E) is a prescription medicine and is strictly for hospital use. It is only administered under the direct supervision and prescription of a qualified ophthalmologist in a hospital or clinic setting. It is never for self-medication.

What are the key precautions to be aware of with Colistin (Polymyxin E)?

Colistin is reserved for multidrug-resistant organisms. When given systemically (IV), it can be nephrotoxic, meaning it can affect the kidneys, so kidney function is closely monitored. It is a prescription eye medicine for hospital use only and should never be used for self-medication. Always inform your doctor about any allergies or other medications you are taking.

References

Medically reviewed by Dr. C Jagadesh Reddy, Chief Surgeon: Cornea, Cataract and Refractive Surgery — last reviewed 2026-07-28.

This page is for general education only and is not a substitute for professional medical advice, diagnosis or treatment. Never self-medicate or reuse an old prescription. Always consult a qualified ophthalmologist before starting, changing or stopping any eye medicine.