Coughing is a protective respiratory reflex action of the body, through which secretions in the respiratory tract or foreign bodies entering the airway can be effectively removed. However, coughing can be harmful, as it can lead to sore throat, hoarseness, respiratory muscle pain and even respiratory bleeding. Prolonged, frequent and violent coughing can seriously affect people’s daily work and rest. Cough is a non-specific symptom of many diseases, and a detailed history must be taken to confirm the clinical diagnosis. 1. Ask the patient patiently about the nature of the cough. A cough without sputum or with very little sputum is called a dry cough. A dry or irritating cough is commonly associated with acute or chronic pharyngitis, laryngeal cancer, the early stages of acute bronchitis, tracheal compression, bronchial foreign bodies, bronchial tumors, pleural disease, primary pulmonary hypertension, and mitral stenosis. Cough with sputum is called wet cough and is commonly associated with chronic bronchitis, bronchiectasis, pneumonia, lung abscess and cavitary tuberculosis. 2. What is the timing and pattern of coughing? Sudden cough is often caused by inhalation of irritating gases or foreign bodies, lymph nodes or tumors compressing the trachea or bronchial bifurcation. Episodic cough can be seen in whooping cough, endobronchial tuberculosis and bronchial asthma (cough variant asthma) with cough as the main symptom. Long-term chronic cough is most often seen in chronic bronchitis, bronchiectasis, lung abscess and tuberculosis. Nocturnal cough is commonly seen in patients with left heart failure and tuberculosis. The cause of nocturnal cough may be related to increased pulmonary stasis and increased vagal excitability at night. 3. What is the tone of the cough? The timbre of a cough refers to the characteristics of the cough sound. The following are generally seen clinically: (1) hoarse cough, mostly due to inflammation of the vocal cords or tumor compression of the recurrent laryngeal nerve; (2) cockle-like cough, manifested as continuous paroxysmal cough with high-pitched inspiratory echo, mostly seen in whooping cough, eccrine, laryngeal disorders or tracheal compression; (3) metallic cough, commonly due to mediastinal tumor, aortic aneurysm or bronchial cancer directly compressing the trachea; (4) cough sound Low or feeble cough sounds are seen in severe emphysema, vocal cord paralysis and extremely debilitated individuals. In addition to a detailed medical history, a thorough physical examination should be performed, including chest X-ray or CT, airway reactivity measurement, pulmonary function plus bronchodilatation test, electrocardiogram, electronic bronchoscopy, cranial CT and some special tests to exclude other diseases that can cause chronic and persistent cough. Cough variant asthma, COPD, chronic bronchitis, cough induced by gastroesophageal reflux, recurrent respiratory infections, classic asthma, posterior nasal drip syndrome, endobronchial tuberculosis and cough induced by angiotensin converting enzyme inhibitors are common causes of chronic cough and need to be carefully differentiated during diagnosis. In addition, cerebral embolism, chronic cardiac insufficiency, esophageal hiatal hernia, hypertension, airway inflammation, swellings, foreign bodies, as well as smoke irritation, emotional instability and anxiety, and dry air at night with open mouth breathing can all cause chronic cough. 4. How should cough be treated? The guidelines for the diagnosis and treatment of cough suggest six principles for the empirical treatment of cough: (1) First, treat the common causes of chronic cough. Domestic and international studies have shown that the common causes of chronic cough are cough variant asthma (CVA), postnasal drip syndrome (PNDS) or upper airway cough syndrome (UACS), eosinophilic bronchitis (EB) and gastroesophageal reflux cough (GERC). (2) The etiology of chronic cough is inferred from the medical history. If the patient mainly presents with nocturnal irritant cough, the patient can be treated first as CVA; if the cough is accompanied by significant acid reflux, belching and heartburn, the treatment of GERC is considered; if the cough persists secondary to a cold, the patient can be treated as post-infectious cough. Those with a history of nasopharyngeal disease, cough with runny nose, nasal congestion, nasal itch, frequent throat clearing, and postnasal drip influenza may be treated first as UACS or PNDS. (3) Empirical treatment with compound preparations that have to cover a wide range and are moderately priced is recommended, such as memin pseudo-lax solution and compound methonamine, which are useful for UACS or PNDS, allergic cough, and post-infectious cough. Those suspected of CVA and EB can be treated with oral hormone therapy for 3~5d first, and then switch to inhaled glucocorticoids or combined β2 agonists after the symptoms are relieved. (4) Those with cough, coughing up pus sputum or runny nose can be treated with antibiotics. Most chronic coughs have an etiology unrelated to infection, and the abuse of antibiotics should be avoided during empirical treatment. (5) Empirical treatment for UACS or PNDS, CVA, and EB is often 1 to 2 weeks, and at least 2 to 4 weeks for GERC. Oral glucocorticoids are usually given for no more than 1 week. Those who are effectively treated empirically continue with a standardized treatment protocol for the appropriate cough etiology. (6) Finally, it is worth noting that empirical treatment must be guided by the etiologic diagnosis and understanding of the local distribution of chronic cough etiology to prevent going down the old path of “chronic cough – chronic bronchitis or pharyngitis – antibiotics plus cough suppressants”. If empirical treatment is ineffective, the cause should be clarified in a timely manner by relevant examinations at a qualified hospital to avoid delays in some important diseases.