Here's what causes bronchitis, how the illness usually spreads and how you can treat symptoms if it affects you or a loved one. Start the day smarter. Get all the news you need in your inbox each ...

Bronchitis is a respiratory illness that occurs when the airways leading into your lungs get irritated, Nagata explains, which leads to the swelling and mucus buildup that causes difficulty breathing.

Understanding the different types of bronchitis can also be helpful in understanding when the illness is and isn't contagious. Chronic bronchitis caused by environmental irritants, for instance ...