Cause of a Chronic Cough

Chronic cough may be caused by a bacterial or viral infection, the result of an irritant in the lungs or airway due to allergies or sinuses draining into the throat. Cancer and diseases that scar lung tissue can also cause a chronic cough that is accompanied by other symptoms. Always consult with a doctor if a cough lasts longer than three weeks.

Lung Cancer

• Chronic cough commonly occurs in smokers and former smokers, though it doesn't always signal lung cancer. Smokers may ignore a chronic cough because they have been told that it is to be expected, but if it is accompanied by coughing up blood, inability to swallow, appetite loss, weight loss with no apparent cause, or severe fatigue, contact your doctor immediately.

Respiratory Tract Infection

• A bacterial or viral infection in the lungs can cause coughing as a way of trying to clear the lungs of mucus. Illnesses such as bronchitis, pneumonia, the common cold and whooping cough can all result in a chronic cough, as can a viral infection in the upper respiratory tract.

Pulmonary Fibrosis

• Pulmonary fibrosis is a disease that causes lung tissue to scar. As more of the lung becomes scarred, less oxygen is able to get into the lungs, which can lead to a chronic cough that doesn't produce mucus, known as a dry cough.

Pleurisy

• Pleurisy occurs when the pleurae, the membranes surrounding the lung, become inflamed. Wet pleurisy occurs when fluid leaks into the pleural cavity, which is the space between the membrane and lungs. When there is no fluid leakage, it's called dry pleurisy. Either condition can lead to a dry cough, which is considered chronic when it takes longer than three weeks to stop.

Asthma

• Coughing is a common symptom of asthma, as are tightness in the chest, shortness of breath, chest pain or pressure, and wheezing. An asthma-related cough is classified as chronic because asthma lasts throughout an individual's lifetime.