Is it possible that non-productive cough turns to productive cough?
Yes. For example, in the case of a common cold or flu, there are often two phases: At first a non-productive (dry) or less productive cough that later turns more and more into a productive cough. When viruses invade the airways, the lining of the respiratory tract may be attacked and impaired. The normal secretion of mucus changes: mucus becomes stickier and adheres in the airways. This phlegm cannot be expelled, and coughing is experienced as very troublesome and exhausting. As the cold progresses, usually more mucus is produced and the cough becomes productive. It is then possible to expel the phlegm by coughing.
