Polymyxin B eye drops are used for seven to 10 days to treat bacterial conjunctivitis and blepharoconjunctivitis. This medication's use as a single agent has been discontinued. Instead, it is prescribed in combination with other antibiotics such as trimethoprim, explains Medscape.
Polymyxin B works by killing bacteria, while trimethoprim stops bacterial growth. Patients are typically prescribed one drop in each affected eye every three hours. Side effects of the eye drops include minor irritation around the area, burning, stinging, itching and blurry vision. The medication should only be used to treat bacterial eye infections, and it does not work on viruses or other microorganisms, explains Medscape.