The causes of runny nose in newborns are mainly divided into the following categories: first of all, caused by cold, which is very common. If the child is infected with rhinovirus or influenza virus after getting cold, there will be acute upper respiratory tract infection, there will be runny nose, cough and fever, which is the most common acute upper respiratory tract infection. You can give your child to drink more warm water appropriately, and the runny nose will be slowly relieved within a week. Secondly, it is caused by neonatal rhinitis, in which the child has runny nose for a longer period of time and has no other special symptoms, such as no other complications like fever and cough. In this case, the child can be given appropriate antihistamine drugs, such as cetirizine syrup, to treat the runny nose symptomatically. You can use cotton swabs dipped in water to clean the child’s nasal cavity, thus effectively relieving the symptoms of runny nose.