A lower respiratory inflammation affecting the windpipe (trachea) and bronchial tubes.

Bronchitis can be caused by viruses, bacteria, or allergies, and it occurs in both acute and chronic forms, the former usually caused by a virus and the latter by allergies. Acute bronchitis often accompanies upper respiratory tract infections associated with cold viruses that spread to the bronchial tubes, causing inflammation and producing excess secretions. More rarely, bronchitis may be associated with Bordetella pertussis (whooping cough) or mycoplasma (parasitic) infections. In some cases, the larynx, or voice box, is also affected, a condition known as laryngotracheobronchitis.

Acute bronchitis is a common childhood disease, especially before the age of four. It occurs more often in boys than girls and is most prevalent in wintertime. Generally, it is preceded by the upper respiratory symptoms of a cold, including a runny nose, sneezing, congestion, and a low fever. Bronchitis begins with...