Erythromycin ointment is applied to newborns’ eyes to prevent a serious eye infection called ophthalmia neonatorum, which can cause blindness in as little as 24 hours after birth. A thin strip of 0.5% erythromycin ophthalmic ointment is placed in both eyes shortly after delivery, and it is the only FDA-approved medication for this purpose in the United States.
What the Ointment Prevents
During a vaginal delivery, a baby’s eyes can come into contact with bacteria in the birth canal. Two infections pose the greatest threat: gonorrhea and chlamydia. Gonorrhea is the more dangerous of the two. A gonococcal eye infection can progress rapidly, causing corneal scarring, perforation of the eyeball, and permanent blindness. Chlamydial conjunctivitis tends to develop more slowly but can still damage a newborn’s eyes if untreated.
The ointment works as a safety net. Even when pregnant women are screened and treated for sexually transmitted infections during prenatal care, not every case is caught. Some infections are acquired late in pregnancy after testing, and some women receive limited or no prenatal care. Universal prophylaxis closes that gap by protecting every baby regardless of the mother’s known infection status.
How and When It’s Applied
The CDC recommends applying erythromycin ointment to both of a newborn’s eyes as soon as possible after birth, ideally in the delivery room and within 24 hours. A nurse or midwife gently pulls down each lower eyelid and places a thin ribbon of ointment along the inner surface. The process takes only a few seconds.
You’ll notice your baby’s vision looks temporarily blurry or their eyelids appear greasy afterward. This is normal and clears on its own. The ointment doesn’t need to be wiped away.
Side Effects Are Minimal
Because the ointment is applied topically to the eyes rather than taken by mouth, very little of the medication enters the bloodstream. The most common effect is temporary blurred vision, which resolves quickly. Mild eye irritation that wasn’t present before application is possible but rare. The ointment does not carry the gastrointestinal side effects associated with oral erythromycin in older infants or adults.
Why Erythromycin Replaced Silver Nitrate
Before erythromycin became the standard, hospitals used silver nitrate drops. Silver nitrate was effective and inexpensive, but it caused a noticeable chemical conjunctivitis: redness, swelling, and discharge that could alarm parents and temporarily impair the baby’s vision. It also had no effect against chlamydia. Silver nitrate is no longer manufactured in the United States, making erythromycin the default and only approved option.
Researchers have studied a dilute povidone-iodine solution as a potential alternative. Early evidence suggests it may be effective, but no povidone-iodine product has been approved for newborn eye prophylaxis in the U.S., and more studies are needed before it could replace erythromycin.
It’s Required by Law in Most States
Most U.S. states mandate newborn eye prophylaxis by law, a practice rooted in over a century of public health efforts to prevent infant blindness. The U.S. Preventive Services Task Force has found convincing evidence that erythromycin ointment prevents gonococcal eye infections in newborns and recommends its use for all babies. The CDC echoed this in 2021, recommending universal prophylaxis for every newborn.
Some parents question whether the treatment is necessary, particularly if the mother tested negative for gonorrhea and chlamydia during pregnancy. The rationale behind universal application is straightforward: screening can miss infections acquired after testing, false negatives occur, and the consequences of an untreated gonococcal eye infection are severe and irreversible. The treatment itself carries almost no risk, so the benefit-to-risk calculation strongly favors applying it to every baby.
What Parents Should Know
If you’re expecting a baby and wondering about the ointment you’ll see applied in the delivery room, here’s the practical picture: the application is quick, painless, and causes only temporary blurriness. It won’t interfere with skin-to-skin contact or breastfeeding. Your baby can still see you, just through a slightly greasy film that fades within minutes to hours.
In states where prophylaxis is legally required, hospitals generally cannot skip the treatment even at a parent’s request, though specific policies vary. If you have concerns, raising them with your obstetrician or midwife before delivery gives you time to understand the requirements where you live and what, if any, alternatives or exemptions exist.