The most common symptoms of chronic obstructive pulmonary disease (COPD) are persistent cough, shortness of breath, feeling like you can't breathe, and excess mucus or phlegm. However, the symptoms can vary, depending on the amount of lung damage. The severity of COPD is divided into five stages, ranging from "at risk" to "very severe." COPD is usually caused by smoking, but other airborne irritants and factors can cause COPD as well.

COPD is a serious and potentially life-threatening illness: It is responsible for more than 130,000 deaths in the U.S. each year. There is no cure for COPD, and the lung damage that results in COPD cannot be reversed, so it is very important to identify the symptoms of COPD early on. However, COPD symptoms may be dismissed as "smoker's cough" or as a normal sign of aging. Symptoms may also be confused with asthma, but they are separate conditions (although some people can have both asthma and COPD).