Bronchitis happens when the tubes that carry oxygen to your lungs become inflamed or swollen. It can happen chronically, where the symptoms are reoccurring or never go away, or it can be acute, where symptoms go away in a few weeks. Acute bronchitis is contagious because it is caused by a bacteria or virus. Chronic bronchitis, however, is not because a specific lung irritant normally causes it. If you think you are experiencing bronchitis or ...