Whether a cough is contagious or not depends on what causes the cough. Common causes of cough include upper respiratory tract infection, acute chronic bronchitis, chronic obstructive pulmonary disease, lung tumors, tuberculosis, and laryngeal tuberculosis. Most causes of cough are not contagious, such as bronchitis, chronic obstructive pulmonary disease, and lung tumors; however, a few causes may appear to spread disease, i.e., tuberculosis, influenza, etc. Respiratory infections caused by tuberculosis, laryngeal tuberculosis and other branching bacilli are more contagious if the patient has obvious cough symptoms, and the sputum may carry a large number of tuberculosis bacteria, leading to the spread of tuberculosis; if the patient has a persistent cough with symptoms such as low fever, night sweats and hoarseness, attention needs to be paid to the screening of tuberculosis and laryngeal tuberculosis, early isolation and specialist hospital consultation. Influenza is a respiratory infection caused by influenza virus infection with mild respiratory symptoms and severe systemic symptoms. If a patient develops a mild cough during the epidemic season but has obvious symptoms such as headache, generalized aches and pains, and persistent high fever, active screening is required. Influenza is a respiratory transmitted disease, so coughing can lead to the spread of influenza virus epidemics, and once a suspected case is detected, early isolation is required, along with timely antiviral treatment with drugs such as oseltamivir. Therefore, whether a cough is contagious or not is mainly related to the cause of the cough. If the cough is due to an infectious disease and the cough can lead to the spread of droplets, then the risk of infection is high and prompt isolation and specialist consultation is needed.