Chest | Pulmonology | Cough (Symptom)
A cough is a reflex action that occurs as an attempt to clear the airways of mucus, sputum, a foreign body, or any other irritants or blockages. The cough reflex consists of three phases: an inhalation, a forced exhalation against a closed glottis, and a violent release of air from the lungs following opening of the glottis, usually accompanied by a distinctive sound. A cough is productive when it brings up mucus or sputum and unproductive, or dry, when it does not.
A cough can be acute if it is present less than three weeks, subacute if it is present between three and eight weeks, and chronic when lasting longer than eight weeks. Coughing can happen voluntarily as well as involuntarily.
Many coughs are due to irritation of the airways by dust, smoke, or a viral infection of the upper respiratory tract. The most common causes of an acute cough include: the common cold; acute sinusitis; pertussis (whooping cough); chronic obstructive pulmonary disease (COPD) exacerbations; allergic rhinitis; non-allergic rhinitis.
For a cough that has lasted for between 3 and 8 weeks, the most common causes are: post-infectious cough; acute sinusitis; asthma. The most common causes of a chronic cough include: post-nasal drip (phlegm draining from the back of the nose into the throat); asthma (and cough-variant asthma); gastroesophageal reflux disease (GERD); eosinophilic bronchitis; medication induced (ACE inhibitors); smoking. Cough is a symptom so specific treatment is directed at the underlying disorder.