Coughing is the body's reflexive response when something irritates the lungs or air passages (including the nasopharynx, oral parts, throat, larynx and upper esophagus). This reflex causes the relevant body part to forcibly expel the irritation or unwanted particles from the air passages.

• Common causes of chronic cough include:
• Chronic infections such as sinusitis, tonsillitis, pharyngitis, laryngitis, bronchitis, chest infections and dental infections, where sticky mucous and inflammation of the throat irritate the air passages. The sticky mucous may also be inhaled into the lungs. Coughing is the reflex to expel this mucous.
• Smoking (which may constantly irritate the air passages)
• Cancer of the throat, oral cavity, lungs or esophagus.
• Medication - certain antihypertensive medication such as Ace inhibitors (note, in particular, medication with names ending with "pril")
• Allergy - allergic rhinitis, throat allergy, cough variant asthma and asthma
• Laryngopharyngeal Reflux (LPR)