Bronchitis is an inflammation of the airways in the lungs called the bronchi. It can be acute (short-term) or chronic (long-lasting). Acute bronchitis is often caused by viruses and leads to coughing and excess mucus production. Chronic bronchitis is usually caused by cigarette smoking and long-term damage to the lungs. Symptoms include coughing, mucus production, wheezing, and shortness of breath. Preventive measures include avoiding tobacco smoke, getting flu shots, and reducing mucus-producing foods.