Cough with blood is called blood in sputum, which has various causes, such as lung tumor, tuberculosis, bronchial dilatation and so on. 1. Lung tumor: it is common in central lung cancer, which may come from tumor rupture and blood leakage or capillary rupture and bleeding, mostly with blood in sputum or intermittent bloody sputum, hemoptysis is rare. It may also be accompanied by emaciation, chest pain, dyspnea and other manifestations. 2. Tuberculosis: The invasion of tuberculosis foci increases the permeability of alveolar capillaries, causing blood in sputum. At the same time, it may be accompanied by low fever, night sweats and other manifestations. 3. Bronchial dilatation: most of the hemoptysis symptoms of bronchial dilatation will appear repeatedly and continuously, can be blood in sputum or hemoptysis, some bronchial dilatation with hemoptysis as the only symptom, but also accompanied by chronic cough, cough, wheezing and other manifestations. There are many reasons for coughing up blood, coughing up blood, it is recommended to go to the hospital in time to find out the cause of the disease, under the guidance of the doctor for standardized treatment, so as not to delay the condition.