Dry cough for more than two weeks should be alert to lung cancer, chronic pharyngitis, chronic bronchitis, tuberculosis and other diseases. 1. Lung cancer: the cause of lung cancer is still unclear, which may be related to smoking, occupational carcinogenic factors, air pollution, heredity and genes. Early symptoms of lung cancer are often irritating dry cough with no or little sputum, which can be aggravated when the tumor causes bronchial stenosis. When the tumor grows into the lumen, there may be intermittent or persistent sputum with blood. 2. Chronic pharyngitis: the cause of this disease is more complicated, and it is considered to be related to occupation, environment, bacteria, pharyngeal reflux and other factors. Patients often have dry throat, sore throat, dry cough and other symptoms, and some patients may also be accompanied by foreign body sensation in the throat. 3. Chronic bronchitis: the cause of the disease is still unclear, may be related to smoking, air pollution, exposure to chemical substances and other factors. Generally, patients with chronic bronchitis often have symptoms of coughing and coughing up sputum, which can also be manifested as chronic dry cough with a longer duration of illness. Some patients may also have symptoms such as wheezing. 4. Tuberculosis: usually due to Mycobacterium tuberculosis infection, and is associated with poor nutrition, poor hygiene, low immunity and other factors. Coughing, coughing up sputum for more than two weeks or blood in sputum are the common suspicious symptoms of tuberculosis. When the cough is mild, it is mainly a dry cough or a small amount of mucus sputum. Dry cough for more than two weeks can also be caused by other diseases, it is recommended that the patient seek medical attention in a timely manner to clarify the cause of the disease and then actively treat it, so as not to delay the condition.