There are many causes of cough. While cough is sometimes just a minor annoyance, it can warn of a more serious problem. Cough can be a symptom of a disease or of a problem, such as a peanut stuck in the airway.
Cough spreads colds and other infections from one person to another.
Occasionally, in certain persons with heart trouble, cough can be lifesaving by helping restore normal beating in a heart experiencing abnormal beating or rhythm. A cough probably begins with irritation of nerves in the respiratory tract. The irritation may come from a plug of mucus in the airway, for example, or from exposure to a chemical aerosol such as hair spray, or postnasal drip, or from a number of other causes. Mucus that is abnormally thick and sticky can be difficult to remove from airways by coughing. Bronchial tubes that are abnormally narrowed and obstructed.