Fortified Colistin Eye Drops: Uses, Brands & Dosage

Fortified Colistin is a special antibiotic eye drop used to treat severe eye infections, particularly those caused by certain resistant bacteria.

Drug class	Antibiotic (Compounded/Fortified)
Type	Single
Forms	Fortified Eye Drop
Common strength	0.19%
Prescription status	Prescription (hospital-prepared)

What Fortified Colistin is used for

Fortified Colistin eye drops are a powerful antibiotic medicine specifically used to treat very serious eye infections. These infections are often caused by bacteria that are difficult to treat with other antibiotics, making Fortified Colistin a crucial treatment option in such cases.

MDR gram-negative (Acinetobacter/Pseudomonas) keratitis: This refers to severe infections of the cornea (the clear front part of your eye) caused by specific types of bacteria called Acinetobacter or Pseudomonas. These bacteria are often ‘multi-drug resistant’ (MDR), meaning they do not respond to many common antibiotics. Fortified Colistin is used when these resistant bacteria are causing a serious infection like keratitis, which can threaten your eyesight if not treated effectively.

In simpler terms, if you have a very stubborn eye infection that other medicines haven’t been able to clear, especially one affecting the cornea, your eye specialist might prescribe Fortified Colistin.

How it works

Fortified Colistin eye drops work by delivering a very strong dose of an antibiotic called polymyxin directly to your eye. Polymyxins are a type of antibiotic known for their ability to combat certain difficult-to-treat bacteria, particularly the gram-negative types like Acinetobacter and Pseudomonas. These bacteria have a unique outer layer that many antibiotics struggle to penetrate. Polymyxins, however, are effective against these bacteria by disrupting their cell membranes, which are vital for their survival. By damaging these membranes, the bacteria can no longer function properly and are eventually killed, helping to clear the infection.

Because it’s a ‘fortified’ preparation, it means the medicine is made at a higher strength (0.19% in this case) than standard eye drops. This high strength is necessary to effectively fight off the very resistant and severe infections it is prescribed for. The direct application to the eye ensures that a concentrated amount of the antibiotic reaches the site of infection, providing a powerful local treatment.

How it’s used

Fortified Colistin eye drops are a powerful medicine and must be used exactly as prescribed by your ophthalmologist. The way you use these drops is very important for them to work effectively and to ensure your recovery.

Typically, when you first start treatment, these drops are given very frequently, often hourly. This frequent dosing ensures a continuous and high level of the antibiotic is present in your eye to fight the severe infection. As your eye starts to improve, your doctor will gradually reduce the frequency of the drops. This process is called ‘tapering’. It’s crucial not to stop using the drops or change the dosing schedule on your own, even if your eye feels better, unless specifically instructed by your doctor.

Here’s a general guide on how to correctly instil eye drops:

Wash your hands: Always wash your hands thoroughly with soap and water before touching your eyes or the eye drop bottle.
Prepare the bottle: Gently shake the bottle if instructed by your doctor or pharmacist. Make sure the tip of the dropper does not touch any surface, including your eye or fingers, to prevent contamination.
Position yourself: Tilt your head back or lie down.
Create a pocket: Gently pull down your lower eyelid with one finger to create a small pocket.
Instil the drop: Hold the dropper bottle above your eye. Look upwards and squeeze the bottle gently to release one drop into the pocket you created.
Close your eye: Close your eye gently for a minute or two. Do not blink excessively or squeeze your eye shut, as this can push the medicine out.
Press the tear duct: You may gently press your finger on the inner corner of your eye (near your nose) for a minute or two. This helps prevent the medicine from draining into your nose and throat too quickly.
Wipe excess: Gently wipe away any excess liquid around your eye with a clean tissue.
Wash hands again: Wash your hands again after applying the drops.

Remember, this medicine is hospital-prepared and will be given to you with specific instructions from your eye specialist. Follow those instructions precisely. If you miss a dose, apply it as soon as you remember, unless it’s almost time for your next dose. Do not double dose to make up for a missed one.

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

Fortified Colistin is a very important medicine, but it comes with specific precautions because of its nature and use. It’s vital to understand these to ensure safe and effective treatment.

Hospital-compounded: This medicine is not available as a standard, pre-packaged retail product. It is specially prepared (‘compounded’) in a hospital or clinic pharmacy. This means it is made fresh for your specific treatment and requires careful handling and storage as instructed by the hospital staff.
Last-line treatment: Fortified Colistin is considered a ‘last-line’ antibiotic. This means it is reserved for severe infections, particularly those that have not responded to other, more common antibiotics. It is used when other treatments have failed or are not expected to work due to the type of bacteria causing the infection. This approach helps preserve its effectiveness for when it is truly needed.
Prescription eye medicine: You absolutely need a prescription from a qualified ophthalmologist to obtain and use Fortified Colistin. It is never for self-medication.
Use only as directed: Always follow the exact instructions given by your eye specialist regarding the dosage, frequency, and duration of treatment. Do not alter the schedule or stop the medicine without consulting your doctor, even if your symptoms improve.
Not for self-use: This medicine is given only by specialists in a hospital or clinic setting and is never for self-use. You will receive it directly from the hospital or clinic pharmacy.
Storage: Store the eye drops as advised by the hospital pharmacy. They may require refrigeration or specific storage conditions due to being freshly compounded.
Contamination: Be extremely careful not to contaminate the dropper tip. Do not let it touch your eye, fingers, or any other surface. Contamination can introduce new germs into the eye, worsening the infection.
Allergies: Inform your doctor if you have any known allergies to antibiotics, especially polymyxins, or any other medications.
Other eye medicines: If you are using other eye drops or ointments, inform your doctor. They will advise you on the correct order and waiting time between different medications.
Warning: 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.

It is crucial to attend all follow-up appointments with your ophthalmologist so they can monitor your progress and adjust your treatment as needed. If you experience any new or worsening symptoms, or any unusual side effects, contact your doctor immediately.

Understanding Eye Infections and Keratitis

Our eyes are precious organs, and sometimes they can get infected. An eye infection occurs when harmful microorganisms like bacteria, viruses, or fungi invade any part of the eye. These infections can range from mild to very severe. One particularly serious type of eye infection is called keratitis. Keratitis is an inflammation or infection of the cornea, which is the clear, dome-shaped front surface of your eye. The cornea plays a crucial role in focusing light onto the retina, allowing us to see clearly. When the cornea gets infected, it can become cloudy, painful, and significantly impair vision. If left untreated, severe keratitis can lead to permanent vision loss or even require surgical intervention.

Some eye infections, especially keratitis, can be caused by very stubborn bacteria that are resistant to many common antibiotics. These are known as multi-drug resistant (MDR) bacteria. Two common types of MDR bacteria that can cause severe eye infections are Acinetobacter and Pseudomonas. When these resistant bacteria infect the cornea, a powerful and specific antibiotic like Fortified Colistin is often needed to effectively fight the infection and save your vision. It’s important to understand that such severe infections require immediate and expert medical attention from an ophthalmologist.

Correctly Using Your Eye Drops and Maintaining Hygiene

Using eye drops correctly is vital for the medicine to work as intended. Incorrect application can reduce the effectiveness of the medicine or even introduce more germs into your eye. Always start by washing your hands thoroughly with soap and water before touching your eyes or the eye drop bottle. This is the most important step to prevent contamination. When you open the bottle, be very careful not to let the tip of the dropper touch anything – not your fingers, not your eye, not any surface. The tip is sterile, and touching it can introduce bacteria into the medicine, which you would then put into your eye. After instilling the drop, close your eye gently for a minute or two. Avoid blinking rapidly or squeezing your eye shut, as this can push the medicine out of your eye before it has a chance to work. You can also gently press on the inner corner of your eye (near your nose) for a minute; this helps keep the medicine in your eye longer. Always wash your hands again after applying the drops.

Maintaining good hygiene is not just about applying drops; it’s also about preventing further infection. Never share your eye drops with anyone else, even if they have similar symptoms. Each bottle is for one person only. If you wear contact lenses, your doctor will almost certainly advise you to stop wearing them during an active eye infection. Follow this advice strictly. Always use clean tissues to wipe away any excess liquid around your eye. Avoid rubbing your eyes, especially with unwashed hands, as this can worsen the infection or spread it to the other eye. Proper hygiene, combined with correct medicine application, is your best defence against eye infections.

Storage, Follow-up, and When to Seek Help

Because Fortified Colistin is a hospital-prepared medicine, its storage instructions are very specific. You must store the eye drops exactly as advised by the hospital pharmacy. They may require refrigeration or have a limited shelf life once opened or prepared. Do not use the drops beyond the expiry date or the period specified by the hospital. Discard any remaining medicine safely as instructed by your healthcare provider.

Regular follow-up appointments with your ophthalmologist are absolutely critical when you are on Fortified Colistin. Your doctor needs to monitor how well the medicine is working, check for any side effects, and adjust the dosing schedule as your eye heals. Do not miss these appointments. If you experience any new symptoms such as increased pain, redness, swelling, discharge, blurred vision, or light sensitivity, contact your ophthalmologist immediately. These could be signs that the infection is not responding as expected or that you are developing a complication. Even if your eye feels better, do not stop the medicine without your doctor’s approval, as stopping too early can lead to the infection returning and becoming even harder to treat. Your doctor is your best guide throughout this treatment journey.

Frequently asked questions

What is Fortified Colistin used for?

Fortified Colistin is a special antibiotic eye drop used to treat severe eye infections, particularly those affecting the cornea (keratitis) and caused by multi-drug resistant bacteria like Acinetobacter and Pseudomonas. It's used when other common antibiotics are not effective.

How does Fortified Colistin work?

Fortified Colistin works by delivering a high-strength dose of a polymyxin antibiotic directly to the eye. This antibiotic targets and damages the cell membranes of specific resistant bacteria, effectively killing them and helping to clear the infection.

What are the common brands of Fortified Colistin in India?

Fortified Colistin is not available as a standard retail brand. It is a 'hospital-prepared' or 'compounded' medicine, meaning it is specially made by the hospital pharmacy for individual patients based on a doctor's prescription.

How should I use Fortified Colistin eye drops?

You must use Fortified Colistin exactly as prescribed by your ophthalmologist. Initially, it's often given hourly, and then the frequency is gradually reduced (tapered) as your eye improves. Always wash your hands before and after use, and be careful not to touch the dropper tip to prevent contamination.

Do I need a prescription for Fortified Colistin?

Yes, Fortified Colistin is a prescription eye medicine and must only be used under the direct supervision of a qualified ophthalmologist. It is never for self-medication and is given only by specialists in a hospital or clinic setting.

What are the key precautions I should take while using Fortified Colistin?

Key precautions include using it only as directed by your ophthalmologist, understanding that it is a hospital-compounded, last-line treatment for severe infections, and never self-medicating. Always ensure proper hygiene during application and follow all storage instructions from the hospital pharmacy. Attend all follow-up appointments.

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.