Polytrim (polymyxin B / trimethoprim): Basics, Side Effects & Reviews
Polytrim (polymyxin B / trimethoprim)

Polytrim (polymyxin B / trimethoprim)

Basics, Side Effects, Reviews & More

Polytrim (polymyxin B / trimethoprim) is a cheap and effective medication used for bacterial infections on the eyes and eyelids, but it must be used many times a day.






Not a controlled medication


Lower-cost generic available


Prescription only

Reviewed by:

Aileen Chu, PharmD, BCPS

Christina Aungst, PharmD

Last reviewed on:

December 4, 2020


What is Polytrim (polymyxin B / trimethoprim)?

How Polytrim (polymyxin B / trimethoprim) works

Polytrim (polymyxin B / trimethoprim) is a combination of two antibiotics that work together to kill bacteria. Polymixin B makes the bacteria's protective covering weaker, and trimethoprim prevents the bacteria from getting nutrients they need to survive.

What is Polytrim (polymyxin B / trimethoprim) used for?

  • Mild to moderate infections on the eye and eyelid, including pink eye

Polytrim (polymyxin B / trimethoprim) dosage forms

Typical dosing for Polytrim (polymyxin B / trimethoprim)

Put 1 drop in the affected eye(s) every 3 hours for 7 to 10 days. Do not use more than 6 doses per day.

Frequently asked questions about Polytrim (polymyxin B / trimethoprim)

Pros and cons of Polytrim (polymyxin B / trimethoprim)


Thumbs UpCheap and effective

Thumbs UpApplied directly where the infection is

Thumbs UpCauses fewer serious side effects than oral antibiotics


Thumbs DownHas to be used multiple times a day for at least a week

Thumbs DownCan cause temporary eye irritation after applying

Thumbs DownContact lenses not recommended while using

Pharmacist tips for Polytrim (polymyxin B / trimethoprim)

Capsule IconBe sure to use Polytrim (polymyxin B / trimethoprim) for the full amount of time your healthcare provider told you to, even if you start to feel better. Stopping Polytrim (polymyxin B / trimethoprim) too soon can cause your infection to come back and be harder to treat.

Capsule IconWash your hands before and after putting Polytrim (polymyxin B / trimethoprim) drops in your eyes. Don't touch the dropper tip with your eye, hands, or any other surface. This will help you avoid contaminating the solution.

Capsule IconDon't wear contacts while using Polytrim (polymyxin B / trimethoprim). It's usually best not to wear contacts while you have an eye infection, since this can affect how quickly your symptoms improve. Be sure to discard the contacts you were wearing before you started using Polytrim (polymyxin B / trimethoprim), as they most likely have bacteria on them. Wear new contacts once your infection is cleared up.

Capsule IconAfter placing a drop in your eye, close your eye and press one finger to the inner corner of your eye by the nose and press lightly for 1 minute. This helps make sure your eye absorbs the drop.

Capsule IconIf you are using Polytrim (polymyxin B / trimethoprim) at the same time as other eye medications, wait 5 minutes between each drop to give your eyes time to absorb each medication. If you are using an eye ointment at the same time as this medication, use Polytrim (polymyxin B / trimethoprim) first, wait 5 minutes, and then apply your eye ointment.

Capsule IconMild irritation from Polytrim (polymyxin B / trimethoprim) is typical and can happen with each dose, within 48 hours of using it, or at any time if you are using this medication for a long time.

Capsule IconKeep the bottle at room temperature for the drug to work properly. Do not put it in the fridge or freezer.

Prices for Polytrim (polymyxin B / trimethoprim) start at just $9.09 with a GoodRx coupon. They’re fast, easy-to-use and free!

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What are the side effects of Polytrim (polymyxin B / trimethoprim)?

With any medication, there are risks and benefits. Even if the medication is working, you may experience some unwanted side effects.

Warning Small Contact your doctor immediately if you experience any of the following:

  • Allergic reactions

Caution Small The following side effects may get better over time as your body gets used to the medication. Let your doctor know immediately if you continue to experience these symptoms or if they worsen over time.

Common side effects

  • Eye irritation - redness, burning, stinging, itching

Other side effects

  • Swollen eyelid(s)
  • Red eyes
  • Tearing

Source: DailyMed

The following side effects have also been reported:

Side effects that you should report to your doctor or health care professional as soon as possible:

  • burning, stinging, or swelling
  • change in vision or blurred vision that will not go away
  • eye pain
  • itching and redness
  • rash

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • temporary blurred vision after applying
  • temporary watering or stinging

What are the risks and warnings for Polytrim (polymyxin B / trimethoprim)?

Polytrim (polymyxin B / trimethoprim) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options

Only use in the eye

Polytrim (polymyxin B / trimethoprim) should only be put on the surface of the eye. Do not swallow it or use this as an injection.

Allergic reactions

Allergic reactions from Polytrim (polymyxin B / trimethoprim) are very rare. If you notice rash, redness, itching, or swelling around your eye or other parts of your face, stop using this medication and contact your provider.

Not for pink eye in newborns

Polytrim (polymyxin B / trimethoprim) is not FDA-approved for prevention or treatment of pink eye in newborn babies. Please ask your infant's provider about other options if this is a concern.

New infection

  • Risk factors: Using Polytrim (polymyxin B / trimethoprim) for too long

It's possible to get a new infection from fungi or bacteria that are resistant to Polytrim (polymyxin B / trimethoprim) after using this medication for a while. Do not use this medication longer than prescribed. Let your provider know if you notice symptoms of a new infection or if the original symptoms do not get better after using Polytrim (polymyxin B / trimethoprim).

No contact lenses

Don't wear contact lenses while using Polytrim (polymyxin B / trimethoprim) since it can affect how quickly your symptoms improve. Throw away the lenses you were wearing before you started using Polytrim (polymyxin B / trimethoprim), as they will most likely have bacteria on them. If you are still having symptoms of your infection after you have finished the prescription, do not start wearing contacts again yet. You might still have an infection.

How much does Polytrim (polymyxin B / trimethoprim) cost?

Polytrim (polymyxin B / trimethoprim) is available as a generic medication and may be significantly cheaper compared to the brand version. Unless there is a specific reason you need the brand, the generic medication will be a better value. For even more savings, use a GoodRx coupon and pay just a fraction of the retail price.

Lowest GoodRx Price
Polytrim (brand)


Lowest GoodRx Price
polymyxin B / trimethoprim (generic)


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Pricing based on most commonly-filled versions: 1 eye droppers (10ml) of polymyxin b/trimethoprim 10000units/1mg/ml

What are alternatives to Polytrim (polymyxin B / trimethoprim)?

There are a number of medications that your doctor can prescribe in place of Polytrim (polymyxin B / trimethoprim). Compare a few possible alternatives below.

Polytrim (polymyxin B / trimethoprim)
Drug Class:Antibiotic


lowest GoodRx price

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Drug Class:Macrolide antibiotic


lowest GoodRx price

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Ciloxan (ciprofloxacin)
Drug Class:Fluoroquinolone antibiotic


lowest GoodRx price

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What is the latest news about Polytrim (polymyxin B / trimethoprim)?

The Truth About Sulfa Allergies: Should You Avoid Other Drugs if You’re Allergic to Bactrim?
The Truth About Sulfa Allergies: Should You Avoid Other Drugs if You’re Allergic to Bactrim?

About 2% of the general population have had an allergic reaction to a “sulfa” antibiotic, most typically trimethoprim/sulfamethoxazole (TMP/SMX), also known as Bactrim or Septra. Pharmacists and physicians used to recommend staying away from all sulfa-containing medications if you’d had allergic reactions to Bactrim — but not anymore. Here’s what’s true and what’s not true ...

What You Need to Know About Medication Allergies
What You Need to Know About Medication Allergies

When you drop off your medications at a pharmacy you may notice that the technician, intern, or pharmacist who greets you and takes your prescriptions may also ask you for an updated list of your allergies. I have seen some patients annoyed by this life-saving question, while others seem to blow it off. Some of the remarks I have ...

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