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.
Trimethoprim eliminates bacteria that cause urinary tract infections. It is used in combination with other drugs to treat certain types of pneumonia. It also is used to treat traveler's diarrhea. Antibiotics will not work for colds, flu, or other viral infections.