Acute bronchitis is an inflammation of the air passages in the lungs that is usually caused by a viral infection such as a cold or the flu. It causes coughing and other breathing problems that typically last around two weeks. While it is usually not a serious illness, it can sometimes be caused by bacterial infections or pollution. Diagnosis involves examining symptoms and listening to the lungs for abnormal sounds. Treatment focuses on relieving symptoms through rest, fluids, medication, and avoiding irritants. Complications are rare in otherwise healthy children.