Trimethoprim + Polymyxin B (Eye Drop)

Trimethoprim + Polymyxin B is an antibiotic eye drop used to treat bacterial conjunctivitis.

Drug class	Antibiotic (Combination)
Type	Combination
Forms	Eye Drop
Common strength	0.1% + 10,000 IU/mL
Common Indian brands	Polytrim (abroad)
Prescription status	Prescription

What Trimethoprim + Polymyxin B is used for

Trimethoprim + Polymyxin B eye drops are prescribed to treat bacterial infections of the eye. Specifically, they are used for:

• Bacterial conjunctivitis

Bacterial conjunctivitis is a common eye infection that causes redness, irritation, and discharge from the eye. This medicine works against a wide range of bacteria, including both gram-positive and gram-negative types, which are common causes of such infections.

How it works

Trimethoprim + Polymyxin B is a combination antibiotic eye drop. It contains two different antibiotics, Trimethoprim and Polymyxin B, which work together to fight bacterial infections. Each antibiotic has a unique way of attacking bacteria, and when combined, they provide a more powerful and broad-spectrum effect against the infection. This dual action helps to kill the bacteria causing the conjunctivitis, leading to relief from symptoms and resolution of the infection.

How it’s used

Always use Trimethoprim + Polymyxin B eye drops exactly as prescribed by your ophthalmologist. The typical dosing involves:

• Instilling 1 drop into the affected eye(s) 4 to 6 times a day.

It is crucial to complete the full course of treatment, even if your symptoms improve sooner. Stopping the medication early can lead to the infection returning or becoming more difficult to treat.

Always follow your ophthalmologist’s exact instructions.

Brands available in India

• Polytrim (abroad)

Brand availability and pricing vary; confirm with your pharmacist.

Precautions & side effects

Before using Trimethoprim + Polymyxin B eye drops, please inform your ophthalmologist about any other medications you are taking, any allergies you have, or any other medical conditions. Key precautions include:

• This medicine is a prescription eye medicine. It must be used 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.
• Trimethoprim + Polymyxin B is considered a useful option for pediatric conjunctivitis.
• Please note that this medicine has limited availability in India and is not currently approved or routinely available here. It is included for reference. Ask your ophthalmologist about approved alternatives that are available in India.

Always consult your doctor if you experience any unusual symptoms or side effects while using this medication.

Understanding Bacterial Conjunctivitis

Bacterial conjunctivitis, often simply called ‘pink eye,’ is a common eye infection that affects the conjunctiva – the clear membrane that covers the white part of your eye and lines the inside of your eyelids. When this membrane gets infected by bacteria, it becomes inflamed, leading to a range of uncomfortable symptoms. You might notice your eyes appearing red or pink, feeling gritty or itchy, and producing a sticky discharge, especially in the mornings, which can sometimes make your eyelids stick together. Your eyes might also water more than usual, and you might experience mild sensitivity to light. While bacterial conjunctivitis can be bothersome, it is usually not serious and typically clears up with appropriate antibiotic treatment, like the one your doctor might prescribe. It’s important to remember that conjunctivitis can be contagious, so good hygiene practices are essential to prevent its spread to others.

Correctly Using Eye Drops and Ointments

Using eye drops or ointments correctly is vital for their effectiveness and to prevent contamination. Here’s a simple guide:

1. Wash Your Hands: Always start by thoroughly washing your hands with soap and water before touching your eyes or the eye drop bottle.
2. Prepare: If you wear contact lenses, remove them unless your doctor advises otherwise. Shake the bottle gently if instructed.
3. Position Yourself: Tilt your head back or lie down. Gently pull down your lower eyelid with one finger to create a small pocket.
4. Administer the Drop: Hold the dropper bottle upside down with your other hand, positioning it directly over your eye. Avoid touching your eye or eyelid with the tip of the dropper to prevent contamination. Squeeze the bottle gently to release one drop into the pocket you created.
5. Close Your Eye: Gently close your eye for a minute or two. Avoid blinking or squeezing your eye shut, as this can push the medicine out.
6. Apply Pressure (Optional but Recommended): Gently press your finger against the inner corner of your eye, near your nose, for about a minute. This helps prevent the medicine from draining into your tear duct and throat.
7. Clean Up: Wipe away any excess liquid around your eye with a clean tissue.
8. Wash Hands Again: Wash your hands again to remove any medication residue.

If you need to use more than one type of eye drop, wait at least 5-10 minutes between different medications to allow each one to be absorbed properly.

General Hygiene, Storage, and When to Seek Help

Maintaining good hygiene is paramount when dealing with eye infections and using eye medications. Always use a fresh, clean tissue to wipe your eyes, and avoid sharing towels, pillowcases, or eye makeup with others. Never touch the tip of the eye drop bottle to your eye or any other surface, as this can introduce bacteria into the bottle. Store your eye drops as directed on the packaging, usually at room temperature and away from direct sunlight. Always check the expiry date and discard any leftover medication once the treatment course is complete or after the recommended period (usually 28 days after opening, even if some medicine remains). Do not save old prescriptions for future use, as the infection might be different, or the medicine might be contaminated.

While Trimethoprim + Polymyxin B is generally effective for bacterial conjunctivitis, it’s crucial to know when to seek further medical attention. If your symptoms worsen, do not improve after a few days of treatment, or if you experience severe eye pain, sudden vision changes, or intense sensitivity to light, contact your ophthalmologist immediately. These could be signs of a more serious condition that requires different treatment. Remember, your ophthalmologist is the best person to guide you through your treatment and address any concerns you may have.

Frequently asked questions

What is Trimethoprim + Polymyxin B used for?

Trimethoprim + Polymyxin B eye drops are used to treat bacterial conjunctivitis, which is a bacterial infection of the eye that causes redness, irritation, and discharge.

How does Trimethoprim + Polymyxin B work?

It is a combination of two antibiotics, Trimethoprim and Polymyxin B. They work together with complementary mechanisms to kill a broad range of bacteria, including both gram-positive and gram-negative types, that cause eye infections.

What are the common Indian brands for Trimethoprim + Polymyxin B?

Trimethoprim + Polymyxin B is not currently approved or routinely available in India. While a brand called Polytrim exists abroad, it has limited Indian availability. Your ophthalmologist can advise you on approved alternatives available in India.

How should I use Trimethoprim + Polymyxin B eye drops?

You should use 1 drop in the affected eye(s) 4 to 6 times a day, or exactly as directed by your ophthalmologist. It's important to complete the full course of treatment.

Do I need a prescription for Trimethoprim + Polymyxin B?

Yes, Trimethoprim + Polymyxin B is a prescription eye medicine. It should only be used as directed by a qualified ophthalmologist.

What precautions should I take while using Trimethoprim + Polymyxin B?

Always use it as prescribed by your ophthalmologist. Do not self-medicate or reuse old prescriptions. It is a useful option for pediatric conjunctivitis. Be aware that it has limited availability in India, and your doctor can suggest alternatives. This information is for general education and not a substitute for professional medical advice.

References

1. Pink Eye (Conjunctivitis) – American Academy of Ophthalmology
2. Conjunctivitis – MedlinePlus
3. Learn about eye health – National Eye Institute (NIH)
4. Blindness and vision impairment – World Health Organization
5. StatPearls – NCBI Bookshelf

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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.