Bronchitis is an inflammation of the bronchial tubes, the airways that carry air to your lungs. It causes a cough that often brings up mucus, as well as shortness of breath, wheezing, and chest tightness. There are two main types of bronchitis: acute and chronic.

The same viruses that cause colds and the flu often cause acute bronchitis. These viruses spread through the air when people cough, or through physical contact (for example, on unwashed hands). Being exposed to tobacco smoke, air pollution, dusts, vapors, and fumes can also cause acute bronchitis. Bacteria can also cause acute bronchitis, but not as often as viruses.