Cough

A cough is a sudden expulsion of air through the large breathing passages which can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following 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. Coughing into one's elbow or toward the ground—rather than forward at breathing height—can reduce the spread of infectious droplets in the air.

Croup ( ), also known as croupy cough, is a type of respiratory infection that is usually caused by a virus. The infection leads to swelling inside the trachea, which interferes with normal breathing and produces the classic symptoms of "barking/brassy" cough, inspiratory stridor, and a hoarse voice. Fever and runny nose may also be present. These symptoms may be mild, moderate, or severe. It often starts or is worse at night and normally lasts one to two days.