Key Message Pediatric chronic cough often involves eosinophilic inflammation; however, objective measurements are not routinely used in treatment decisions. Accurate biomarkers of eosinophil activity, such as eosinophil-derived neurotoxin (EDN) and cationic proteins (ECP), should be used. EDN, which overcomes the shortcomings of ECP, recently received approval for use in Korean healthcare settings. EDN and ECP can play a role in treatment period and drug selection decisions.