What You Should Know About Bacitracin/Polymyxin B Side Effects

If your doctor prescribed Bacitracin/Polymyxin B ophthalmic ointment for a bacterial eye infection, you're probably wondering what side effects to expect. The good news: this medication has been used for decades, and most people tolerate it well. But like any antibiotic, it can cause reactions — and some of them need immediate medical attention.

This guide covers the common side effects, the serious ones you shouldn't ignore, and practical tips for managing them.

What Is Bacitracin/Polymyxin B?

Bacitracin/Polymyxin B is a combination antibiotic ointment that treats bacterial eye infections. It contains two active ingredients — Bacitracin Zinc and Polymyxin B Sulfate — that work together to kill bacteria. Bacitracin targets gram-positive bacteria, while Polymyxin B handles gram-negative bacteria, giving the combination broad-spectrum coverage.

You may know it by brand names like Polysporin Ophthalmic, AK-Poly-Bac, or Polycin. It's commonly prescribed for conditions like bacterial conjunctivitis (pink eye), blepharitis, and keratitis. For more details, see our complete guide on what Bacitracin/Polymyxin B is and how it works.

Common Side Effects

Most side effects of Bacitracin/Polymyxin B ophthalmic ointment are mild and temporary. They usually improve as your body adjusts to the medication or resolve once you finish the course of treatment.

• Temporary blurred vision — This is the most common side effect. Because it's an ointment, it creates a film over your eye that blurs your vision for several minutes after application. This is normal and expected.
• Mild stinging or burning — A brief stinging sensation when you first apply the ointment is common, especially if your eye is already irritated from the infection.
• Mild eye redness or itching — Some irritation at the application site can occur. This is usually mild and short-lived.
• Puffy eyelids — Minor swelling around the eyelids may happen, particularly in the first day or two of treatment.

These side effects usually don't require any special treatment and shouldn't cause alarm. If they persist beyond a few days or get noticeably worse, let your doctor know.

Serious Side Effects — When to Call Your Doctor

Serious side effects are uncommon with Bacitracin/Polymyxin B, but they can happen. Contact your doctor right away — or go to the emergency room — if you experience any of the following:

• Allergic reaction — Hives, difficulty breathing, swelling of your face, lips, tongue, or throat. This requires immediate emergency care. Bacitracin is a known allergen, and some people develop sensitization over time.
• Severe eye redness, swelling, or itching — A significant worsening of redness or swelling (beyond what your infection is causing) could signal an allergic reaction to the medication.
• Eye pain — Mild discomfort is one thing, but sharp or worsening eye pain could indicate a more serious problem.
• Vision changes — Beyond the expected temporary blur from the ointment itself, any persistent changes in your vision — clouding, floaters, light sensitivity — should be reported.
• White patches on your eyes — This could indicate a fungal superinfection or another complication that needs immediate evaluation.
• Increased discharge or crusting — If your eye discharge is getting worse rather than better after 2-3 days of treatment, the infection may not be responding to this antibiotic.
• Signs of a new infection — Antibiotics can sometimes allow opportunistic infections (like fungal infections) to develop. New or different symptoms during treatment warrant a call to your doctor.

Specific Populations

Some groups should take extra precautions with Bacitracin/Polymyxin B:

Pregnant or Breastfeeding

Bacitracin/Polymyxin B is classified as Pregnancy Category C, meaning it hasn't been well-studied in pregnant women. The good news is that topical and ophthalmic forms have minimal systemic absorption, so the risk is likely low. However, you should tell your doctor if you're pregnant or breastfeeding so they can weigh the benefits against any potential risks.

Children

While pediatricians commonly prescribe ophthalmic antibiotics for children with bacterial eye infections, the safety and effectiveness of Bacitracin/Polymyxin B ophthalmic ointment hasn't been fully established in patients under 18. Your child's doctor will determine if it's the right choice based on the specific situation.

Older Adults

No special dose adjustments are needed for older adults. Since the medication is applied topically with minimal systemic absorption, age-related kidney or liver changes typically aren't a concern.

People with Kidney Problems

Both Bacitracin and Polymyxin B can be nephrotoxic (harmful to the kidneys) when given systemically. With the ophthalmic ointment, systemic absorption is minimal — but if you have severe kidney disease and are using other nephrotoxic medications, mention it to your doctor.

How to Manage Common Side Effects

Here are practical tips for dealing with the most common side effects:

For Blurred Vision

• Apply the ointment at bedtime when possible — your vision won't matter while you sleep, and the ointment has more time to work.
• If you need to apply during the day, do it when you don't need to drive or do close-up work for 20-30 minutes.
• Don't rub your eyes after applying — let the ointment spread naturally.

For Stinging or Burning

• Make sure your hands are clean and the ointment tube tip doesn't touch your eye or any surface.
• The stinging typically lasts less than a minute. If it lasts significantly longer, note it for your doctor.
• A cool (not cold) clean compress on closed eyelids after application can help soothe irritation.

For Mild Swelling or Redness

• A cool compress for 5-10 minutes can reduce puffiness.
• Avoid touching or rubbing your eyes.
• Don't wear contact lenses during treatment.

General Tips

• Complete the full course of treatment (usually 7-10 days), even if your symptoms improve early. Stopping too soon can allow the infection to come back.
• Don't share your ointment with anyone else — even if they have similar symptoms.
• If you're using other eye medications, wait at least 5-10 minutes between applications, and use the ointment last (since it can block the absorption of eye drops).

Final Thoughts

Bacitracin/Polymyxin B ophthalmic ointment is generally well-tolerated, and most side effects are mild and temporary. Blurred vision and brief stinging are the most common — and both are expected with any eye ointment.

The key thing to watch for is signs of an allergic reaction (severe itching, swelling, difficulty breathing) or symptoms that get worse instead of better after a few days. If either happens, contact your doctor promptly.

If you're having trouble finding Bacitracin/Polymyxin B at your pharmacy due to the current shortage, Medfinder can help you locate pharmacies that have it in stock near you.