A typical course of COPD might proceed as follows. For a period of about 10 years after cigarette smoking begins, symptoms are usually not very noticeable. After this, the patient generally starts developing a chronic cough with the production of a small amount of sputum. It is unusual to develop shortness of breath during exertion below the age of 40, after which it becomes more common and may be well developed by the age of 50. However, although all COPD patients have these symptoms, not all cigarette smokers develop a notable cough and sputum production, or shortness of breath.
Most patients with COPD have some degree of reversible airways obstruction. It is therefore likely that, at first, treatment will lead to some improvement or stability in lung function. But as COPD progresses, almost all signs and symptoms except cough and sputum production tend to show a gradual worsening. This trend can show fluctuations, but over the course of 4 or 5 years, a slow deterioration becomes evident.
Repeated bouts of increased cough and sputum production disable most patients and recovery from coughing attacks may take a long time. Patients with severe lung damage sleep in a semi-sitting position because they are unable to breathe when they lie down. They often complain that they awaken during the night feeling "choked-up," and they need to sit up to cough.
Survival of patients with COPD is closely related to the level of their lung function when they are diagnosed and the rate at which they lose this function. Overall, the median survival is about 10 years for patients with COPD who have lost approximately two-thirds of their normally expected lung function at diagnosis.