The two most common causes of tearing in one eye in babies are conjunctivitis and congenital tear duct obstruction, and it is important to pay attention to the details of how to distinguish between these two diseases. Conjunctivitis is usually after birth, the eyes are normally not tearing, only the last few days of tearing symptoms, usually accompanied by more eye droppings, only need to point anti-inflammatory eye drops, such as Tobias drops can be treated. If the tearing started after the child was born and has continued until now, it is likely to be a congenital tear duct obstruction. You need to go to the hospital for tear duct unblocking in time. So pay attention to distinguish the specific symptoms of the child and then do the analysis and treatment.