Erythromycin ophthalmic ointment is an antibiotic applied directly to the eye to treat bacterial eye infections. It’s also the standard medication given to newborns shortly after birth to prevent serious eye infections. Available as a 0.5% ointment, it works by stopping bacteria from growing on the surface of the eye and the tissue lining the eyelids.
Bacterial Eye Infections in Adults and Children
The most common reason erythromycin ophthalmic ointment is prescribed is bacterial conjunctivitis, often called pink eye. This type of pink eye causes redness, swelling, and a thick discharge that may crust over the eyelids overnight. Erythromycin targets many of the same bacteria that penicillin does, making it effective against a range of common bacterial strains that infect the eye’s surface.
Beyond conjunctivitis, the ointment treats other superficial eye infections, including bacterial infections of the cornea and eyelid margins. It’s sometimes used alongside other medications when a more complex infection requires broader coverage. However, some strains of bacteria have developed resistance to erythromycin, so your prescriber may switch to a different antibiotic if the infection doesn’t improve within a few days.
Newborn Eye Prophylaxis
If you recently had a baby and noticed a nurse applying ointment to your newborn’s eyes, that was almost certainly erythromycin. The CDC recommends erythromycin 0.5% ophthalmic ointment as a single application in both eyes as soon as possible after delivery. This is done for virtually all newborns in the United States, regardless of whether the birth was vaginal or cesarean.
The purpose is to prevent a condition called ophthalmia neonatorum, a serious eye infection that newborns can develop from bacteria encountered during delivery. Two bacteria are of particular concern: the organisms responsible for gonorrhea and chlamydia. Even if the mother has tested negative for these infections, prophylaxis is given as a safety measure because untreated neonatal eye infections can cause permanent vision damage. If the ointment isn’t applied in the delivery room, guidelines call for it to be given within 24 hours of birth. A fresh, unopened tube is used for each infant to avoid any risk of contamination.
How to Apply the Ointment
For treating an active eye infection, the typical application involves squeezing a ribbon of ointment about 1 centimeter long (roughly the width of a fingertip) directly into the lower eyelid. You do this by gently pulling the lower lid down to create a small pocket, then laying the ribbon of ointment along the inside of that pocket. After releasing the lid, close your eye gently for a moment to let the ointment spread across the surface.
The frequency depends on how severe the infection is. For superficial infections, the ointment may be applied up to six times daily. Your vision will blur temporarily after each application because the ointment is thick and greasy. This is normal and clears as the ointment absorbs. Avoid touching the tip of the tube to your eye, fingers, or any other surface, since this can introduce new bacteria into the tube.
What to Expect During Treatment
Because the ointment sits on the eye’s surface rather than absorbing instantly like drops, it provides longer contact time with the infected tissue. That’s an advantage for fighting infection, but it does mean a few minutes of blurred vision after each dose. Many people find it easiest to apply the ointment right before bed, when the blur won’t interfere with daily activities. If your prescription calls for multiple daily applications, plan around tasks that require sharp vision, like driving.
Most bacterial eye infections improve noticeably within two to three days of starting treatment. Even once your eye feels better, finish the full course prescribed to reduce the chance of the infection returning or bacteria becoming resistant. If you see no improvement after several days, or if the redness and discharge worsen, contact your prescriber. The infection may involve a resistant strain that needs a different antibiotic.
Side Effects
Erythromycin ophthalmic ointment is generally well tolerated. The most common complaint is temporary blurred vision from the ointment’s greasy base. Some people notice mild stinging or irritation when applying it. Allergic reactions are rare but possible. If you develop increasing redness, swelling, or itching that seems worse than the original infection, stop using the ointment and contact your prescriber, as this could signal a sensitivity to erythromycin.
Storage and Handling
Store the tube at room temperature, between 68°F and 77°F. Keep it away from excessive heat and do not let it freeze, as either extreme can break down the medication. Always replace the cap tightly after each use. If the ointment changes color or texture, discard it and get a replacement.