Bronchitis. Bronchitis usually starts with a cold caused by a virus. In bronchitis, due to the weakened immunity, some of your own bacteria get down into your airways to the lung and produce heavy mucous which eventually turn purulent (yellow, gray, or green). The main symptoms are heavy cough and production of this thick sputum. There is usually no fever. There may be chest tightness or wheezing.
Different types... There are basically 2 different types of bronchitis: acute and chronic. Acute bronchitis usually consists of cough productive of discolored sputum, fever as well as upper respiratory tract symptoms and body aches. It usually has a sudden onset and completely resolves in a few days but may need antibiotics. Chronic bronchitis, a form of copd, consists of cough w/ sputum and is not cured.