Bronchitis is an inflammation of the bronchi, which are the main passageways in her lungs. Inflammation is caused by by virus, bacteria, allergies, or autoimmune diseases. Bronchitis is characterized by prolonged, excessive coughing. Acute bronchitis is a one-time condition that lasts for several weeks, while chronic bronchitis is an ongoing condition that lasts at least several months or longer. While there are roughly 10–12 million visits to medical professionals every year for bronchitis, most cases turn out to be acute bronchitis, which can be treated at home and usually clears up on its own with proper care.