A high-velocity expulsion of gas from the airways that serves to clear them of mucus, cellular and microbial debris, or foreign bodies. An absence or inability to cough can lead to recurrent pneumonia. Cough can be acute (<2 weeks), subacute/protracted (2 to 4 weeks), or chronic (>4 weeks).


  • Cough is the most common symptom presenting to primary care physicians in the United States and worldwide.
  • Chronic cough accounts for up to 38% of pulmonary outpatient visits.
  • Healthy children can have a nonpathologic cough.
  • School-age children typically experience up to 10 instances of cough per day.


  • Cough results from a complex reflex phenomenon initiated by cough receptors that is mediated through the brainstem.
  • The receptors are located in the respiratory tract from the larynx to the segmental bronchi, paranasal sinuses, external auditory canal, and stomach and are triggered by thermal, chemical, mechanical, or inflammatory stimuli.
  • Cough is generally reflexive but may sometimes be voluntarily initiated or suppressed.

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