Are topical antibiotic ointments sterile?

I noticed that the active and inactive ingredients in topical bacitracin zinc ointment and bacitracin zinc eye ointments are the same. The only difference that I can see is the eye ointment is marked as sterile. But woulden’t the topical ointment have to be sterile too since you are applying it to open wounds, and whatever bacteria, virus or fungus is inside it would infect the wound?

The tubes and bottles are sterile until you open them, and sterile enough if used properly. Eye drop bottles can transmit infection if you hold the bottle so it hits the eye. You want to wipe the tube with a piece of gauze rather than shoving it into the open wound.

Although active ingredients may be the same, not everything can be used in the eye — although some antibiotic ointments can.

The difference between your eye ointment and your topical ointment is, I presume, that the eye ointment is in single use containers. (If it isn’t I’d be interested to know). Pretty much all topical ointments are multi-use containers, so sterility would be lost once you open them and use them for the first time. For that reason there just isn’t any point in making them sterile. They’re made cleanly (I mean, really cleanly), they will contain antimicrobial preservatives (unless the formulation is intrinsically anti-microbial, such that further preservation is not required) and there will be low limits on acceptable contamination (which may be zero, but that’s not strictly the same thing as being sterile).

If your eye ointment is multi-use and sterile, then obviously that too loses it’s sterility once opened.

Generally things are not manufactured sterile unless they need to be. Sterilisation comes at a financial cost, and it’s a fairly extreme thing to do to a medicine; so while it may not actually harm the product, it certainly doesn’t do it any good (other than making it sterile, of course).


Eye ointment in a multi-use container is packaged in a container with a device in the applicator that resembles the ball in a ballpoint pen, and this makes the applicator one way only. I’m sure everyone has had toothpaste, hydrocortisone cream, etc. suck back into the tube after it came out? That can’t happen with one of these tubes.

Eye medicine comes in both drop and ointment form. The drops are multiple doses and only one drop is required. In medicine, there is a spectrum including sterile, clean and various amounts of contamination. An open bottle probably is less sterile than a sealed one, but if used properly should be clean and usable.

Is OTC topical bacitracin zinc ointment safe to use in the the eye?

I wouldn’t recommend it.

Indeed - it turns out that the USP monograph says:

Bacitracin Ophthalmic Ointment is a sterile preparation of Bacitracin in an anhydrous ointment base.

  • to my surprise. You live and learn.

So the Ophthalmic Ointment is manufactured sterile and evidently has a dosing device to minimise contamination in use (per NWH - above). It won’t stay sterile once the unit is broached, but there’s more in place to make it as clean as possible throughout use than there is for the regular ointment. And that comparison is a function of what is needed for the site of application.


You should follow the directions on the ointment. There is erythromycin ointment made for eyes, for example. I don’t know if it is different, but you don’t play around with your eyes. Unless recommended by the manufacturer, I wouldn’t use it.