1. Common causes and treatments of chronic cough Chronic cough is a common clinical problem and is the most common symptom seen in respiratory medicine. China’s cough diagnosis and treatment guidelines classify cough into acute cough, subacute cough and chronic cough according to the duration of cough, and chronic cough refers to cough for more than 8 weeks, with cough as the only symptom, ineffective treatment with antibiotics and no abnormal findings on routine chest X-ray, i.e. chronic cough of unknown origin cough. There are many clinical causes of unexplained chronic cough, and the following are common: upper airway cough syndrome, cough variant asthma, non-asthmatic eosinophilic bronchitis, gastroesophageal reflux, etc. Most of the relevant tests such as history taking, lung function test, bronchial excitation test, allergen test, induced sputum test, 24h esophageal PH test, etc. can clarify the etiological diagnosis and give the corresponding etiological Treatment and symptomatic therapy can significantly improve cough symptoms. For primary care hospitals that do not have the conditions to perform relevant tests, sometimes a suspicious diagnosis can be made based on the characteristics of the medical history and diagnostic treatment can be given, and the diagnosis can be disproved if the symptoms improve significantly after treatment. For chronic cough due to UACS, CVA, and NAEB, the onset of which is related to chronic inflammation of the airways, anti-inflammatory therapy targeting airway inflammation can be given, including inhaled glucocorticoids, short-term oral glucocorticoids, and leukotriene modulators; for UACS, antihistamines, decongestants, and nasal hormones should still be given; for GERD, acid-control agents should be given. If the symptoms do not improve with diagnostic treatment, the original diagnosis should be considered wrong and further examinations, including chest CT and fibrinoscopy, should be performed in time to clarify the etiological diagnosis. 2. Cough variant asthma accounts for only 25% of chronic coughs In the past, chronic coughs commonly found in clinical settings were often misdiagnosed as chronic bronchial, bronchitis, pharyngitis, etc., and given large amounts of antibiotic treatment or only general cough suppressants, resulting in coughs that could not be relieved and patients repeatedly seeking medical attention, making coughs persistent and a headache for both patients and physicians. Since the publication of the first guidelines for the diagnosis and treatment of chronic cough in the United States in 1998, there has been a significant improvement in the global understanding and treatment of chronic cough. Nowadays, clinicians have realized that chronic cough is not always the common chronic bronchitis, bronchitis, pharyngitis, etc. Many etiologies can cause chronic cough, and treatment for the etiology can bring the cough under control. This treatment has indeed brought the cough under control in some patients. However, CVA accounts for only about 25% of the causes of chronic cough, and not all chronic coughs of unknown origin are CVA. In the above case, if the patient was suspected of having CVA in an external hospital and had ineffective inhaled glucocorticoids or even oral hormones, she should not still be limited to the original diagnosis and should undergo further relevant investigations as soon as possible to clarify the etiologic diagnosis to avoid delaying her condition. In this patient, due to repeated oral prednisone, there were foci of intrapulmonary tuberculosis, but no abnormal findings were found in the chest radiograph at the beginning of the disease. When multiple etiologies coexist, multiple etiologies should be treated simultaneously. Chronic cough can have a single etiology or two or three etiologies at the same time, making clinical diagnosis and treatment of the etiology more complex and difficult. According to a foreign survey, about 16% of chronic coughs are caused by two causes and about 1% by three causes at the same time, commonly UACS, CVA and GERD can co-exist in one patient and together cause the cough. In this group of patients, antihistamines or nasal hormones should be given to treat UACS, and inhaled hormones should be given to treat CVA, and acid suppressants should be given to GERD. The cough was characterized by dry cough, obvious at night, easy to cough when smelling irritating odor or cold air, accompanied by nasal congestion, runny nose and sneezing, and a positive bronchial excitation test, which led to the diagnosis of UACS and CVA. The patient’s symptoms did not improve significantly and he still had a severe cough. At another follow-up visit, the patient’s medical history was taken carefully and it was found that the patient had acid reflux and belching, and the presence of GERD was suspected. Therefore, clinically, for chronic cough with multiple etiologies coexisting, multiple etiologies should be treated simultaneously. 4. Effects of chronic cough on patients Chronic cough that does not heal over a long period of time can have a great impact on the patient’s mind and body. Cough can lead to general malaise, fatigue, insomnia, muscle pain, hoarseness, vomiting, urinary incontinence, and violent coughing can also lead to rib fractures and fainting, as well as fear of malignant tumors due to coughing. Therefore, in addition to emphasizing the treatment of the cause of the cough, appropriate symptomatic treatment should be given. 5. Chronic cough is easily misdiagnosed and has rare causes In addition to the common causes mentioned above, chronic cough should also take into account rare causes and cases that are easily misdiagnosed or missed, such as the above example of endobronchial tuberculosis, which is not uncommon in China. However, on close auscultation, a limited croup in the left upper lung is found, which is not consistent with CVA or typical asthma, and inhaled hormone therapy for asthma is ineffective, even oral hormone is ineffective. Therefore, in clinical practice, careful chest auscultation is very important in chronic cough and can sometimes reveal clues to the diagnosis. In addition, do not give oral hormones in undiagnosed cases to avoid delaying the diagnosis or even leading to exacerbation of the disease. The case cited in this article is a typical case of tuberculosis spreading to the lungs due to the lack of timely anti-tuberculosis treatment for endobronchial tuberculosis and repeated oral hormone administration. Other cases, such as benign and malignant endobronchial occlusions, may also be associated with cough only, with no abnormal findings on chest radiograph. There are also clinical cases of chronic cough due to smoking that are often overlooked by physicians and patients. Therefore, patients with smoking cough should first be actively advised to quit smoking while undergoing routine investigations and targeted treatment.