Antibiotic Eye Drops

If you think OTC eye drops are confusing, just wait until you dive into the world of topical antibiotics. There are roughly 1200 options, but only about 10 are useful. For this article, I’ll focus on antibacterial drops. As a comprehensive ophthalmologist, I rarely use antifungals, so it’s not reasonable to expect people in other fields to use them. Honestly, if you find yourself thinking “you know what, this could be a fungal infection of the eye,” please stop thinking and call an ophthalmologist. Antivirals are used a little more frequently than antifungals, but I’ll save the herpes discussion for another day.

A quick word on dosing: For drops, start with 1 drop every 4 hours while awake (between 4 and 6 drops per day). For ointment, 3 times per day is usually enough. Severe infections need more frequent dosing, but these patients should be seen by an eye doctor within 24 hours.

As always, I have no financial interest in any of these products, which is bullshit.

thick & goopy


Erythromycin ointment is one of the most useful topical antibiotics we have. It’s reasonably broad spectrum and really thick, so it acts as an effective lubricant. I love this option for young kids. Children tend to cry when you come at them with eye drops or ointment (adults cry too, but it’s much less sad). I prefer erythromycin because it won’t be washed out easily and it sticks around longer, requiring fewer applications. Some doctors and caregivers find drops easier to administer. Both are good options as long as the medication gets in the eye.


I use bacitracin ophthalmic for patients with an erythromycin allergy. The only reason this isn’t my default ophthalmic ointment is because bacitracin is a common NON-ophthalmic ointment and I don’t want patients to get the two mixed up. Regular bacitracin is not great for the eyes.

the workhorse

Polymyxin B Sulfate and Trimethoprim (Polytrim)

Cheap, broad spectrum, cheap, cool names, and did I mention, it’s also really cheap? I like Polytrim for uncomplicated corneal abrasions (no infection present). ALL corneal abrasions need to be covered with antibiotics. When you have an epithelial defect in the cornea, it’s an invitation for King Pseudomonas and his merry gang of pathogens to feast on your cornea. A topical antibiotic will help prevent that from happening. The only downside to Polytrim is that it’s bacteriostatic, which makes it less ideal in the setting of active infection, but as a preventive measure it’s perfect. You can also say “I’m sending you home with Polymyxin B Sulfate and Trimethoprim” in front of the patient and they will definitely think you know what you’re doing.

the swiss army knife

Neomycin/Polymyxin B/Dexamethasone (Maxitrol), Tobramycin/Dexamethasone (Tobradex)

These two medications are God’s gift to ophthalmologists. I love using this for flares of blepharitis, a disease which affects somewhere in the neighborhood of 600 billion people. It’s also great for infectious conjunctivitis, episcleritis, pingueculitis, and most other itises which affect the ocular surface. Adding a little steroid to an antibiotic helps hasten recovery and gets the patient feeling better, faster. Both of these medications exist in ointment and drop form. Although I am a huuuuuuge fan of these combo meds, I recommend against any non-ophthalmologist/optometrist from prescribing them. Steroid induced glaucoma is a common adverse effect with prolonged use of topical steroid. Let us make the decision to start Maxitrol or Tobradex, which I’m happy to do, I love them so much.

the old reliables

Second Generation Fluoroquinolones (Ciprofloxacin, Ofloxacin)

The second generation FQs are perfect when all you need is a little whiff of antibiotic to clear an infection. These drops have been around awhile and are my go-to for small peripheral corneal ulcers (90% of contact lens related corneal ulcers) or suspected bacterial conjunctivitis. I tend to go with Ofloxacin over Ciprofloxacin, but honestly I don’t have a good reason why. Ciprofloxacin has better pseudomonas coverage, but in general, if I think King Pseudomonas is involved, I’m going with a bigger gun.

Small, peripheral corneal ulcers can be treated initially with second generation FQs. Make sure to have the patient follow up with an eye doctor.

Small, peripheral corneal ulcers can be treated initially with second generation FQs. Make sure to have the patient follow up with an eye doctor.

the big guns

Fourth generation Fluoroquinolones (Gatifloxacin, Moxifloxacin)

Now we’re getting to the big boys. I use one of these when a patient comes in with a large, central ulcer that has the potential to result in permanent scarring or cause significant corneal thinning. As far as which 4th generation FQ to choose, I know what you’re thinking, Gatifloxacin all the way right? I don’t blame you. That name sounds like a machine gun designed to shoot 50 microliter aliquots of bacteria busting medication directly at the cornea. Unfortunately, Gatifloxacin isn’t always available at some commercial pharmacies, so I tend to go with Moxifloxacin, which is easier to find, and just as effective.

Pseudomonas is tricky. 4th gen FQs work fairly well, but there are enough reports of resistance to this class that it makes me nervous. If a patient strolls in with a large, central ulcer, terrible vision, and they’ve been sleeping in a hot tub while wearing contacts, I have to assume King Pseudomonas has planted his fat ass on the cornea. I’ll culture the ulcer, start Moxifloxacin hourly, and follow the patient daily until I see improvement. If I do not see improvement within 48 hours, I am quick to escalate to better anti-pseudomonas coverage.

This ulcer has King P written all over it. For an ulcer this severe, I’m going straight to fortified antibiotics, then tailoring therapy based on culture data.

This ulcer has King P written all over it. For an ulcer this severe, I’m going straight to fortified antibiotics, then tailoring therapy based on culture data.

Wait, so what about the 3rd generation FQs? Levofloxacin is a decent option, but the price jump from 2nd to 3rd generation is significant, so you might as well go with the 4th generation, which is similar to Levo in terms of cost.

the nuclear option

For vision or eye threatening bacterial infections of the cornea, fortified antibiotics are often necessary. “Fortified” means doubling or tripling the concentration of the antibiotic and typically requires access to a compounding pharmacy, so don’t try to hit up Walgreens for fortified antibiotics. In the absence of culture data to tailor treatment, you have to stay broad spectrum. Fortified tobramycin for gram negatives, including Pseudomonas and fortified vancomycin for gram positives. At this point, your average ophthalmologist (me) is trying to get this patient to a tertiary medical center with robust ophthalmology resources. Just talking about fortified antibiotics gives me horrifying flashbacks to nights spent culturing melting eyes in residency at 3 am.

topical antibiotics that will make your local ophthalmologist furrow their brow and say, “hmm…interesting”

Sulfacetamide (just use polytrim)

Gentamicin (only acceptable if you are trying to treat serratia, which you are not)

Finally, if you are not sure if you should start a patient with a red eye on a topical antibiotic, let us make the decision. Any ophthalmology private practice worth a damn should be able to get a patient in to be seen within 24 hours M-F. If it’s the weekend and you can’t find an ophthalmologist, either go to the nearest golf course and find one, or call us. These patients are pretty easy to triage over the phone. If you don’t have anybody you can talk to, err on the side of prescribing an antibiotic. At worst, the patient is on a drop that isn’t really doing anything for a few days. It’s not the end of the world.