Head-to-head comparisons of medication uses, side effects, warnings, and more.
Key takeaways
Gentak (gentamicin) and Polytrim (polymyxin B/trimethoprim) are both prescription antibiotics used to treat bacterial eye infections, but they have some key differences. Gentak is an aminoglycoside antibiotic that works by blocking bacteria from making proteins needed for their protective covering, and it comes in both eye drop and ointment forms. Polytrim, on the other hand, is a combination of two antibiotics: polymyxin B, which breaks the bacteria's outer covering, and trimethoprim, which stops bacteria from making folic acid. Polytrim is only available as eye drops. Gentak is typically used every 4 hours or more frequently for severe infections, while Polytrim is used every 3 hours up to 6 times a day. Gentak can cause temporary eye irritation and blurry vision from the ointment, whereas Polytrim can cause eye irritation and increased sensitivity to light. Both medications are available in lower-cost generic forms and should be used exactly as prescribed to avoid new infections or resistance.
Gentamicin (Gentak)
Polytrim (polymyxin B / trimethoprim)
Gentamicin (Gentak)
Polytrim (polymyxin B / trimethoprim)
Summary of Gentamicin vs. Polytrim
Summary for Aminoglycoside antibiotic
Prescription only
Gentamicin (Gentak) is a popular, affordable antibiotic for treating different types of bacterial eye infections. It comes as an eye drop and an eye ointment.
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.
Indications of Gentamicin vs. Polytrim
Indications for
•Bacterial infections of the eye or eyelid
Indications for
•Mild-to-moderate infections on the eye and eyelid
Pros and Cons of Gentamicin vs. Polytrim
Pros and Const for Aminoglycoside antibiotic
Pros
•Treats various bacterial eye and eyelid infections
•The ointment form requires fewer doses per day compared to most alternatives.
•Available as a lower-cost, generic form
Cons
•The ointment form tends to be messy and harder to put in the eye.
•Can cause temporary eye irritation or burning
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