Table 2.

Major aetiological causes of chronic cough in children^* and examples.

1	Post-infectious: typically shows spontaneous resolution over time
2	Airway infections (protracted/recurrent/persistent): Protracted bacterial bronchitis, chronic suppurative lung disease, bronchiectasis, cystic fibrosis, immune deficiency/ciliary dyskinesia, alpha-1 antitrypsin deficiency, other chronic infections e.g., tuberculosis and atypical mycobacteria
3	Airway anomaly: Primary or secondary tracheobronchomalacia, congenital airway and pulmonary malformation
4	Airway inflammation: Asthma, eosinophilic bronchitis, environmental pollutants
5	Airway aspiration: Primary airway aspiration, secondary aspiration owing to gastroesophageal reflux, foreign body aspiration
6	Upper airway associations: Rhinitis, sinusitis
7	Tic and somatic syndrome
8	Extra-pulmonary: Drug-induced, cardiac, vagal nerve branches stimulation (e.g., Arnold's ear reflex)
9	Other specific diseases associated with chronic cough: Interstitial lung disease or tumors

^*Some overlap, for example, chronic cough related to primary ciliary dyskinesia can be both infection and inflammation.