Head-to-head comparisons of medication uses, side effects, warnings, and more.
Key takeaways
Polytrim (polymyxin B / trimethoprim) and Tobrex (tobramycin) are both antibiotics used to treat bacterial eye infections, but they belong to different classes and have some key differences. Polytrim is a combination of two antibiotics, polymyxin B and trimethoprim, which work together to kill bacteria by breaking their protective covering and stopping them from making folic acid. Tobrex, on the other hand, is an aminoglycoside antibiotic that kills bacteria by blocking their ability to make proteins and damaging their protective covering. Polytrim is typically used every 3 hours for 7 to 10 days, while Tobrex can be used as eye drops every 4 hours for mild infections or more frequently for severe infections, and also comes in an ointment form that requires fewer doses per day. Both medications can cause temporary eye irritation and swelling. Polytrim is available only as a generic, while Tobrex is available in both brand-name and generic versions. Neither medication should be used longer than prescribed to avoid new infections or resistance.
Polytrim (polymyxin B / trimethoprim)
Tobramycin (Tobrex)
Polytrim (polymyxin B / trimethoprim)
Tobramycin (Tobrex)
Summary of Polytrim vs. Tobrex
Summary for Antibiotic
Prescription only
Polytrim (polymyxin B / trimethoprim) is a combination antibiotic eye drop. It's used to treat mild-to-moderate bacterial eye infections, such as pink eye, in adults and children ages 2 months and older. The typical dose is 1 drop applied directly in the eye(s) every 3 hours for 7 to 10 days. Some of the more common side effects of this eye drop include symptoms of eye irritation, such as redness, stinging, and itching. Polytrim (polymyxin B / trimethoprim) is available as a lower-cost generic.
Summary for Aminoglycoside antibiotic
Prescription only
Tobramycin (Tobrex) is an antibiotic that's used to treat different types of bacterial eye infections. It can be used for people ages 2 months and older. Tobramycin (Tobrex) comes as an ophthalmic solution (eye drops) and eye ointment that are used multiple times per day. It's available in both brand-name and generic versions. The most common side effects include eyelid itching, eyelid swelling, and eye redness. Like with all antibiotics, you shouldn't stop treatment too early because your infection could come back or get harder to treat.
Indications of Polytrim vs. Tobrex
Indications for
•Mild-to-moderate infections on the eye and eyelid
Indications for
•Bacterial infections of the eye or eyelid
Pros and Cons of Polytrim vs. Tobrex
Pros and Const for Antibiotic
Pros
•Can treat a variety of eye infections in adults and children
•Available as a lower-cost generic
•Applied directly on the eyes, so it has less side effects than oral antibiotics
Cons
•Has to be used every 3 hours for at least a week
•Can cause temporary eye irritation after applying
•Can make your eyes more sensitive to light
Pros and Const for Aminoglycoside antibiotic
Pros
•Treats various bacterial eye and eyelid infections
•Ointment form requires fewer doses per day than most alternatives
•Eye drop form is available as a lower-cost generic
Cons
•Can cause temporary eye irritation
•Might require more frequent dosing throughout the day for severe infections
•Ointment form tends to be messy and harder to put in the eye