Bronchitis is a condition in which the bronchial tubes, the tubes that carry air to your lungs, become inflamed. (For more information on the bronchial tubes and the airways. People who have bronchitis often have a cough that brings up mucus. Mucus is a slimy substance made by the lining of the bronchial tubes. Bronchitis also may cause wheezing (a whistling or squeaky sound when you breathe), chest pain or discomfort, a low fever, and shortness of breath. There are two main types of bronchitis: acute (short term) and chronic (ongoing).