A cough is your body's way of responding when something irritates your throat or airways. An irritant stimulates nerves that send a message to your brain. The brain then tells muscles in your chest and abdomen to push air out of your lungs to force out the irritant.
An occasional cough is normal and healthy. A cough that persists for several weeks or one that brings up discolored or bloody mucus may indicate a condition that needs medical attention.
At times, coughing can be very forceful — the velocity of air from a vigorous cough can approach 500 miles an hour. Prolonged, vigorous coughing is exhausting and can cause sleeplessness, headaches, urinary incontinence and even broken ribs.