Chronic bronchitis is a chronic inflammation of the bronchi (medium-size airways) in the lungs. It is generally considered one of the two forms of chronic obstructive pulmonary disease (COPD). It is defined clinically as a persistent cough that produces sputum (phlegm) and mucus, for at least three months per year in two consecutive years.
Bronchitis may be indicated by a cough (also known as a productive cough, i.e. one that produces sputum), shortness of breath (dyspnea) and wheezing. Occasionally chest pains, fever, and fatigue or malaise may also occur. Mucus is often green or yellowish green and also may be orange or pink, depending on the pathogen causing the inflammation.
Tobacco smoking is the most common cause. Pneumoconiosis and long-term fume inhalation are other causes. Allergies can also cause mucus hypersecretion, thus leading to symptoms similar to asthma or bronchitis.