Bronchitis is a lower respiratory tract disease in which the mucus membranes of the bronchi — tiny airways which link the trachea and lungs — become inflamed due to infection or injury. There are two types of bronchitis, known as acute and chronic bronchitis, each with a specific pattern of causes and symptoms. Common signs and symptoms of both types of bronchitis include coughing and difficulty breathing; other symptoms of bronchitis differ depending upon whether the condition is acute or chronic.
Bronchitis is often caused by bacterial or viral infection, and such cases are more common during the winter months. Bacteria which cause bronchitis include Mycoplasma pneumoniae, and viruses such as influenza A and B can also cause bronchitis. When bacteria and viruses cause bronchitis, the condition often develops alongside an upper respiratory tract infection such as a cold or influenza.
In most cases, acute bronchitis is caused by a viral or bacterial infection. Symptoms of acute bronchitis include wet coughing which produces mucus, as well as a runny nose and sore throat, congested nasal passages, and fever. These symptoms of bronchitis develop as a result of the body’s efforts to eliminate the invading pathogen and eliminate the mucus that builds up in the lungs. Decongestants, non-steroidal anti-inflammatory drugs, and expectorants are commonly used to treat acute symptoms of bronchitis.
Not all cases of bronchitis are caused by infectious organisms. Some cases can be caused by inhalation of dust, fumes, and chemicals which irritate the respiratory tract and lead to inflammation. Inhalation of irritants such as chemicals and tobacco smoke are more likely to cause chronic rather than acute bronchitis.
Symptoms of chronic bronchitis differ significantly from those of acute bronchitis. In chronic disease, the symptoms of bronchitis include coughing, wheezing, and difficulty breathing, without the nasal congestion and fever caused by the acute form. These symptoms are exacerbated on exertion. Many people with chronic bronchitis find their cough is worse in the morning, with mucus that appears green or yellow in color. If enough damage is done to the lungs, blood may be coughed up along with the mucus.
Most symptoms of chronic bronchitis are the result of damage to delicate lung tissue. As the bronchi suffer repeated bouts of damage, they become chronically inflamed and swollen, causing cells to produce more mucus. As a result of increased mucus production and swelling, the airways become blocked, making breathing more difficult. These symptoms of bronchitis can be treated with corticosteroids and bronchodilators, which reduce inflammation and widen the bronchi, making breathing easier.