Polymyxin B And Trimethoprim Ophthalmic


Polymyxin B and trimethoprim ophthalmic combination is used to treat bacterial infections of the eye including conjunctivitis (pinkeye; infection of the membrane that covers the outside of the eyeball and the inside of the eyelid) or blepharoconjunctivitis (infection of the membrane that covers the outside of the eyeball and the inside and outer parts of the eyelid). Polymyxin B and trimethoprim are in a class of medications called antibiotics. They work by killing bacteria that cause infections.

Side Effects Of Polymyxin B And Trimethoprim Ophthalmic

Ophthalmic polymyxin B and trimethoprim may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • eye burning, redness, irritation, or stinging
  • eye tearing

Some side effects can be serious. If you experience any of these symptoms, call your doctor immediately:

  • rash
  • itching
  • eyelid swelling

Ophthalmic polymyxin B and trimethoprim may cause other side effects. Call your doctor if you have any unusual problems while using this medication.

Warnings & Precautions

Before using ophthalmic polymyxin B and trimethoprim:

  • tell your doctor and pharmacist if you are allergic to polymyxin B, trimethoprim, any other medications, or any of the ingredients in polymyxin B and trimethoprim ophthalmic solution. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had any medical condition.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while using ophthalmic polymyxin B and trimethoprim, call your doctor.
  • tell your doctor if you wear contact lenses. You should not wear contact lenses while you have symptoms of bacterial conjunctivitis or while you are using eye drops for treatment.
  • you should know that bacterial conjunctivitis spreads easily. Wash your hands often, especially after you touch your eyes. When your infection goes away, you should wash or replace any eye makeup, contact lenses, or other objects that touched your infected eye(s).

Dosage Of Polymyxin B And Trimethoprim

The combination of polymyxin B and trimethoprim comes as a solution (liquid) to instill in the eye. It is usually instilled once in the affected eye(s) every three hours (maximum of 6 doses in 24 hours) for 7 to 10 days. Use it at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Use ophthalmic polymyxin B and trimethoprim exactly as directed. Do not use more or less of it or use it more often than prescribed by your doctor.

After you instill polymyxin B and trimethoprim eye drops, be careful not to let the tip of the bottle touch your eye, fingers, face, or any surface. If the tip does touch another surface, bacteria may get into the eye drops. If you think your eye drops have become contaminated, call your doctor or pharmacist.

You should expect your symptoms to improve during your treatment. Call your doctor if your symptoms do not go away or get worse, or if you develop other problems with your eyes during your treatment.

Use ophthalmic polymyxin B and trimethoprim until you finish the prescription, even if you feel better. If you stop using ophthalmic polymyxin B and trimethoprim too soon, your infection may not be completely cured and the bacteria may become resistant to antibiotics.

To instill the eye drops, follow these steps:

  • Wash your hands thoroughly with soap and water.
  • While tilting your head back, pull down the lower lid of your eye with your index finger to form a pocket.
  • Hold the dropper (tip down) with the other hand, as close to the eye as possible without touching it.
  • Brace the remaining fingers of that hand against your face.
  • While looking up, gently squeeze the polymyxin B and trimethoprim dropper so that a single drop falls into the pocket made by the lower eyelid.
  • Remove your index finger from the lower eyelid.
  • Close your eye and tip your head down as though looking at the floor.
  • Place a finger on the tear duct and apply gentle pressure for 2-3 minutes.
  • Replace and tighten the cap on the dropper bottle. Do not wipe or rinse the dropper tip.
  • Wash your hands and if necessary your child’s hands after instillation to remove any medication.

Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.


Keep all appointments with your doctor.

Do not let anyone else use your medication. Ask your pharmacist any questions you have about refilling your prescription of polymyxin B and trimethoprim.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information on polymyxin B and trimethoprim has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.