Acute bronchitis is usually not serious. It is very common and is usually mild enough to be treated at home. However, sometimes acute bronchitis develops into a more serious condition, such as pneumonia, especially in people with other health issues. Though this is rare, you should contact your doctor right away if your symptoms get worse. You should also talk to your doctor if you have repeated bouts of acute bronchitis, as this might be a sign that you are developing a more serious condition known as chronic bronchitis. Chronic bronchitis is a serious, long-term illness caused by damage to the bronchial tubes, which are the airways that connect your windpipe (trachea) and your lungs.