Coughing is an important defensive reflex that protects from aspiration of foreign materials, and enhances clearance of secretions and particulates from the airways. Healthy children may cough on a daily basis; one study documented an average of 11 cough episodes every 24 hours . However, a cough may also be the presenting symptom of a serious underlying pulmonary or extrapulmonary disease. The causes of chronic cough in children are quite different from that of adults, so evaluation and management of children should not be based on adult protocols. Adolescents 15 years and older may be evaluated using guidelines for adults . (See "Evaluation of subacute and chronic cough in adults".)
The differential diagnosis of chronic cough in children includes subacute and chronic infections (eg, bacterial bronchitis, pertussis, mycoplasma, and tuberculosis), foreign body aspiration, and cough-dominant asthma (table 1) . Gastroesophageal reflux, upper airway cough syndrome (formerly known as postnasal drip syndrome), and sinusitis are sometimes implicated because of associations with chronic cough in adults, but their role in causing chronic cough in children is controversial . Less common disorders must be excluded if the cough is unusually severe and/or frequent, or when there is evidence of failure to thrive, growth retardation, purulent sputum, exertional dyspnea, hypoxemia, chest pain, or hemoptysis. (See "Causes of chronic cough in children".)
An approach to the diagnosis and management of chronic cough in children is presented here. Approaches to wheezing and stridor in children are presented separately. (See "Approach to wheezing in children" and "Wheezing illnesses other than asthma in children" and "Assessment of stridor in children".)
Epidemiologic studies of cough in children have been hampered by the variable definitions used for defining chronicity, the presence of other concomitant symptoms (eg, wheezing), the lack of widely accepted objective clinical endpoints to measure cough severity, and the tendency for cough to resolve spontaneously [4,5].
Despite these limitations, chronic cough appears to be common, with an estimated prevalence of 5 to 7 percent in preschoolers, and 12 to 15 percent in older children [6,7]. Cough is more common among boys than girls up to 11 years of age , and may be less common in developing countries than in affluent countries .