There are many reasons why the elderly always cough, commonly due to chronic bronchitis, lung infection, lung cancer and so on. 1. Chronic bronchitis: Elderly patients with a long history of smoking have chronic non-specific inflammation of the trachea and bronchus, which may be caused by the increase of mucus vesicles accompanied by glandular ducts dilatation, resulting in mucosal epithelial cilia adhesion to stimulate the wall of the tubes and cause coughing. 2. Lung infection: due to the low resistance of the elderly, it is easy to be invaded by foreign pathogens, so that the mucous membrane of the lungs appears to be edematous, and the exudation of inflammatory secretion will stimulate the mucous membrane of the bronchial tubes, which will cause reflexive coughing. 3. Lung cancer: it is more likely to be seen in the elderly. Lung cancer invades the tracheobronchus or mediastinum, causing irritation in the area, which is manifested as persistent irritating cough. Total cough in the elderly may also be caused by other factors, such as gastroesophageal reflux disease, cough variant asthma, upper airway cough syndrome, pulmonary fibrosis, etc. It is recommended that the patients should go to the hospital in time to clarify the cause of the disease, and take treatments under the guidance of doctors to avoid aggravation of the disease.