Cough

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Template:SignSymptom infobox | }} A cough is a sudden, often repetitive, spasmodic contraction of the thoracic cavity, resulting in violent release of air from the lungs, and usually accompanied by a distinctive sound. Coughing is an action the body takes to get rid of substances that are irritating the air passages. A cough is usually initiated to clear a buildup of phlegm in the trachea; air may move through this passage at up to 480 km/h (300 mph) during a contraction. Coughing can also be triggered by a bolus of food going down the trachea instead of the esophagus, due to a failure of the epiglottis, although this may result in choking instead. Frequent or chronic coughing usually indicates the presence of a disease. Provided the patient is a non-smoker and has a normal chest X-ray, the cause of chronic cough in 93% of all patients is due to asthma, reflux (heartburn) or post-nasal drip. Other causes of chronic cough include chronic bronchitis and medications such as ACE inhibitors. Coughing can happen voluntarily as well as involuntarily.

1 Cause
2 Complications
3 Treatment
4 See also
5 External links

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Cause

The physiological action of coughing is responsible in part to the vagus nerve, which runs through the lungs to the brain. The vagus nerve is activated when capsaicin is released, which stimulates the sensory nerve endings. Centrally acting cough suppressants, such as codeine and dextromethorphan, reduce the urge to cough by inhibiting the capsaicin-induced sensory nerve by depolarization of the vagus nerve.

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Complications

In severe cases, prolonged coughing can cause fatigue fractures of lower ribs and costochondritis, an inflammation of the connective tissue between the breastbone and the ribs. It can also lead to fainting spells when coughs are prolonged and forceful. In certain cases, it can even lead to abdominal or pelvic hernias.

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Treatment

Coughs can be treated with cough medicines. Dry coughs are treated with cough suppressants (antitussives) that suppress the body's urge to cough, while productive coughs (coughs that produce phlegm) are treated with expectorants that loosen mucus from the respiratory tract.

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