Background: The similarity in the mechanism of action between paracetamol and ibuprofen can cause similar side effects. However, in preterm neonates with feeding intolerance, intravenous (IV) paracetamol has replaced oral ibuprofen. Therefore, a comparison of the effectiveness and side effects is essential. Methods: In this retrospective cohort study, the data of 118 preterm infants with a definite diagnosis of patent ductus arteriosus (PDA), including 59 patients who received oral ibuprofen and...