For a child presenting with cough and a normal physical examination, what is the most common cause of chronic cough?

A chronic cough in children with an otherwise normal physical examination can have several potential causes, but the most common is asthma. Asthma is characterized by chronic airway inflammation and hyperreactivity, which can lead to episodes of coughing, particularly at night or during physical exertion. Many children with asthma may not exhibit wheezing or other physical signs during periods of symptom-free intervals, making it difficult to diagnose based solely on a physical examination.

In the context of chronic cough, asthma often presents as a recurrent or persistent cough that is notably dry and can be triggered by allergens or respiratory infections. Its prevalence in the pediatric population also supports its classification as a common cause of chronic cough in children. This aligns with the understanding of the condition's pathophysiology, as well as epidemiological data indicating asthma is one of the leading causes of chronic cough in the pediatric demographic.

Other conditions such as post-nasal drip, gastroesophageal reflux disease, and protracted bacterial bronchitis are indeed also causes of chronic cough but are less commonly identified in children with a normal physical examination compared to asthma. For instance, post-nasal drip might cause cough but is generally accompanied by other signs of upper respiratory tract involvement, which may not be present in a simply cough without