Cough and asthma.

Cough is a common symptom in office practice. Though troublesome, it serves to maintain normal function of respiratory tract. Chronic or recurrent cough may be caused by variety of diseases, asthma being the most common amongst them. Cough, wheeze and breathlessness are classical features of asthma syndrome. Many diseases may lead to this syndrome. Asthmatic children present with cough of variable intensities and patterns. At times, wheeze and breathlessness may not be clinically apparent. It was well known that all that wheezes is not asthma but now it is well understood that every asthmatic child does not wheeze. In an acute attack of asthma, cough often starts at the end of wheezing episode. It leads to expulsion of thick, stringy mucus often in the form of casts. Though cough is a minor symptom during acute attack, it ensures removal of secretions and avoid complications. Cough is a prominent symptom in persistent asthma especially between acute exacerbations. Episodic nocturnal cough may be the only symptom of chronic asthma. Children with cough variant asthma do not wheeze. It is postulated that they have milder degree of airway hyperresponsiveness and higher wheezing threshold. However, they show all the characteristics of asthma on laboratory tests. Cough represents bronchial hyperresponsiveness and is not a measure of asthma. Hence it may be caused by many diverse etiologies such as gastroesophageal reflux, enlarged adenoids, sinusitis or tropical eosinophilia. Cough in such conditions mimicks asthma and relevant tests may be necessary for proper diagnosis.