Cough is a common symptom of respiratory illness experienced by most people. The majority of them are related to acute infections of the respiratory tract and recover after treatment such as anti-infection or even self-bought cough medicines. Some people, however, do not respond to various treatments, significantly affecting their lives and work. In addition to some serious diseases causing cough such as lung cancer, there are also some specific causes of persistent cough that require further examination to clarify the diagnosis and give the correct treatment to shorten the course of the disease and avoid irreversible consequences. Lung cancer is one of the most common malignant tumors and is the cancer that causes the most deaths. Lung cancer is often associated with long-term heavy smoking, chronic bronchitis, family history of cancer and work in factories and mines, and is often associated with blood in sputum, vague chest pain and weight loss during persistent cough. When a patient has a persistent cough that does not resolve and has any of the above conditions, a prompt chest X-ray or CT examination is required. When the cough has been present for more than 8 weeks and there are no obvious abnormalities on chest CT examinations, etc., the cough is clinically referred to as chronic cough (slow cough). The common causes of chronic cough are mainly cough variant asthma, upper airway cough syndrome, post-infectious cough, and gastroesophageal reflux disease. Rare causes include eosinophilic bronchitis, tracheal tumors, tracheobronchial endotracheal tuberculosis, and tracheal amyloidosis. Certain medications such as angiotensin-converting enzyme inhibitors anti-hypertensive drugs can also cause a persistent cough that is relieved when the medication is discontinued. Cough variant asthma is a specific type of asthma with cough as the main symptom, often waking up at night or in the early hours of the morning with a pronounced throat tingling and breathlessness. Cough variant asthma requires prompt and standardized treatment according to typical asthma, otherwise it can develop into typical asthma and cause chronic obstructive pulmonary disease and respiratory failure, which can seriously affect quality of life and shorten life expectancy. Upper airway cough syndrome is a clinical syndrome of chronic rhinitis and pharyngitis with chronic cough. The pathogenesis is unclear and is mainly related to chronic inflammatory stimulation of the upper airway and leakage of secretions into the lower airway, often manifested as recalcitrant cough at night and morning cough. These patients often have no obvious abnormal chest effects, and the mucosa of the throat often has chronic inflammatory changes, typically manifesting as rough cobblestone-like changes in the mucosa. Cough is another common cause after acute upper respiratory tract infections, some of which are also associated with asthma-like manifestations, including respiratory hyperresponsiveness. However, this respiratory hyperresponsiveness grams to recover gradually, unlike asthma. Gastroesophageal reflux disease is a common disorder of the GI tract and patients often experience, acidity and heartburn. Some patients may not have any GI discomfort and first present with a persistent nocturnal cough. Gastroscopy and pH measurement of the lower esophagus can clarify the diagnosis, and the cough can be relieved after suppressing gastric acid and reducing esophageal reflux. However, the condition is prone to recurrence. Other rare causes of persistent cough can be clearly diagnosed with further tests. Most coughs can be treated by targeting the cause with satisfactory results. Therefore, if you have a cough that does not resolve, you need to see a specialist for a standard examination and treatment. In addition, air pollution can aggravate coughs from any of the above causes; smoking is another important cause of cough aggravation. For your own health and the health of all people, you need to promote healthy living habits and awareness of self-protection, as well as a big picture view of protecting the environment.