Erythromycin ophthalmic ointment is typically prescribed for 5 to 7 days for bacterial eye infections, though your specific course depends on the type and severity of infection. The most important rule: use it for the full duration your prescriber specified, even if your eyes feel better within a few days.
Typical Treatment Length for Eye Infections
For bacterial conjunctivitis and other superficial eye infections, most prescriptions run 5 to 7 days. During that time, you’ll apply the ointment up to six times daily depending on how severe the infection is. Milder cases may only need two to three applications per day, while more aggressive infections call for the higher end of that range.
You should notice improvement within 2 to 3 days of starting treatment. If your symptoms haven’t changed at all by then, contact your prescriber. That could mean the infection isn’t bacterial (antibiotics won’t help a viral infection) or that the bacteria causing it don’t respond well to erythromycin.
Why You Should Finish the Full Course
It’s tempting to stop once the redness and discharge clear up, but finishing the entire prescription matters. Stopping early leaves surviving bacteria in the eye, and those survivors are the ones most likely to resist the antibiotic. That can lead to a rebound infection that’s harder to treat the second time around. Even if your eyes look and feel completely normal with a few days of ointment left, keep applying it on schedule.
Newborn Eye Prophylaxis Is Different
If your baby received erythromycin ointment at birth, the treatment course is much shorter. This is a single application, not an ongoing regimen. The CDC and the U.S. Preventive Services Task Force both recommend a one-time ribbon of ointment (about 1 centimeter) placed in each of the newborn’s eyes within 24 hours of delivery. The purpose is to prevent eye infections that can be passed during birth, particularly from gonorrhea and chlamydia. No repeat doses are needed.
How to Apply Each Dose
Each dose uses a small amount of ointment, roughly 1 centimeter (about a third of an inch) squeezed from the tube. To apply it, gently pull your lower eyelid down to create a small pocket between the lid and your eye. Lay the ribbon of ointment into that pocket without letting the tube tip touch your eye or eyelid. Then close your eye for a minute or two to let the ointment spread across the surface.
Your vision will blur temporarily after application. The ointment is greasy by design, which helps it stay on the eye longer than drops would, but it does coat the surface for several minutes. Plan around this, especially if you drive or do detailed work. Applying your last dose of the day at bedtime is a common approach since the blurriness won’t matter while you sleep.
Contact Lenses During Treatment
Don’t wear contact lenses while using erythromycin ointment. The greasy base of the ointment coats lenses, and wearing contacts during an active eye infection risks trapping bacteria against the cornea. Wait until you’ve completed the full course of treatment and your symptoms have fully resolved before putting lenses back in. If you wore contacts before the infection started, consider replacing them with a fresh pair, since bacteria can cling to lens surfaces and carrying cases.
Risks of Using It Too Long
Using erythromycin ointment beyond the prescribed duration carries its own problems. Prolonged antibiotic use in the eye can disrupt the normal balance of microorganisms on the eye’s surface, potentially allowing resistant bacteria or fungi to take hold. If your infection hasn’t cleared by the end of your prescribed course, the answer isn’t to keep using the same ointment longer. Go back to your prescriber for re-evaluation, as you may need a different antibiotic or a different diagnosis altogether.