Babies get pink eye through several routes depending on their age: newborns most commonly pick it up during birth from infections in the mother’s birth canal, while older infants catch it the same way adults do, through contact with contaminated hands, respiratory droplets, or allergens. The specific cause matters because some forms are harmless and clear on their own, while others need prompt treatment to protect your baby’s vision.
Pink Eye Passed During Birth
The birth canal is the most significant source of pink eye in newborns. Two sexually transmitted infections pose the greatest risk: chlamydia and gonorrhea. Both can transfer to a baby’s eyes during vaginal delivery. Vertical transmission rates are high when a mother’s infection is untreated: over 30% for gonorrhea and up to 50% for chlamydia. Among babies born to mothers with gonorrhea specifically, up to 48% develop eye infection.
These two infections behave differently once they take hold. Gonorrhea-related pink eye appears fast, usually between days 2 and 5 after birth, with heavy, pus-like discharge. Chlamydial conjunctivitis shows up later, typically 5 to 14 days after birth, and can affect one or both eyes. Left untreated, either infection can progress to corneal scarring and permanent blindness. Gonorrhea can, in rare cases, spread beyond the eye to cause meningitis or bloodstream infection.
Other bacteria picked up during delivery, including staph and strep species, can also cause newborn pink eye, generally appearing between days 2 and 7. This is why prenatal screening for sexually transmitted infections is a routine part of pregnancy care.
Irritation From Hospital Eye Drops
Nearly all hospitals in the United States apply antibiotic eye drops (typically erythromycin) to newborns shortly after birth to prevent bacterial eye infections. These drops themselves can cause a mild chemical irritation that looks like pink eye: slightly red eyes with some eyelid swelling. This reaction is not an infection. It clears up on its own within 24 to 36 hours and doesn’t need treatment.
Viral Pink Eye in Older Babies
Once babies are past the newborn stage, viral conjunctivitis becomes the most common type. The vast majority of cases are caused by adenoviruses, the same family of viruses responsible for many colds. Babies catch these viruses through direct contact with an infected person’s tears, nasal secretions, or contaminated surfaces like toys, burp cloths, and hands.
Viral pink eye typically starts suddenly in one eye and spreads to the other within 24 to 48 hours. The hallmark is watery (not thick or goopy) discharge, along with redness and a general look of discomfort. It’s highly contagious. Babies can spread the virus to others for 10 to 14 days from when symptoms first appear, which is why it tears through daycare settings so quickly. There’s no antibiotic that treats it since it’s viral, so it resolves on its own, though keeping the eye clean with a warm, damp cloth helps with comfort.
Bacterial Pink Eye From Everyday Contact
Beyond the newborn period, babies can also develop bacterial pink eye from common bacteria that live on skin and in the respiratory tract. This happens when a baby rubs their eyes with unwashed hands, when a caregiver touches the baby’s face without clean hands, or when bacteria spread from an ear infection or sinus infection to the eye. Bacterial pink eye tends to produce thicker, yellowish or greenish discharge that can crust the eyelids shut after sleep. Unlike viral cases, bacterial pink eye responds to antibiotic eye drops.
Allergic Pink Eye
Allergic conjunctivitis is less common in very young babies but becomes more relevant as infants grow and develop sensitivities to environmental triggers. House dust mites, pet dander (especially from cats and dogs), mold spores, and pollen are the most frequent culprits. The allergens trigger an immune response that makes the eyes red, watery, and itchy. Both eyes are almost always affected at the same time, which helps distinguish allergic pink eye from infectious types. Reducing exposure to the trigger is the primary way to manage it.
Blocked Tear Ducts: A Common Lookalike
About 5% of infants are born with a partially blocked tear duct, and this condition closely mimics pink eye. The blockage traps tears, creating a warm, moist environment where normal skin bacteria can multiply. The result is watery eyes, crusty discharge, and sometimes mild swelling, all of which look a lot like conjunctivitis.
The key difference is that a blocked tear duct doesn’t cause the redness and inflammation of the eye’s surface that true pink eye does. The white part of the eye stays white, and the discharge comes from the inner corner near the nose rather than coating the entire eye. A blocked tear duct can, however, lead to secondary infections if bacteria build up enough, so it’s worth having your pediatrician confirm which one you’re dealing with.
Signs That Need Urgent Attention
Most pink eye in babies is uncomfortable but not dangerous. However, certain symptoms signal something more serious. Eye pain (in a baby, this looks like inconsolable crying that worsens when the eye area is touched), extreme swelling of the eyelids, cloudiness over the colored part of the eye, or any change in how the baby responds to light all warrant prompt medical evaluation. Pink eye can occasionally cause inflammation of the cornea, the clear front layer of the eye, which affects vision. Newborns under 28 days old with any eye discharge should be seen quickly, since the infections acquired during birth carry the highest risk of complications.