After a cough, some people spit out sputum with blood or blood spots, or full blood sputum, which inevitably causes panic and fear. This is bleeding from the respiratory tract and lungs below the larynx that is coughing out through the mouth, which is medically known as hemoptysis. The causes of hemoptysis are many and can be broadly classified into three categories: respiratory diseases, lung diseases and heart diseases. Among the respiratory diseases, the main ones that cause hemoptysis are bronchiectasis, chronic bronchitis and lung cancer. Lung diseases are mainly lung infections, such as tuberculosis, pneumonia, and lung abscess. Among them, pulmonary tuberculosis is one of the most common causes of hemoptysis. Heart diseases such as mitral valve stenosis, atrial septal defect, and patent ductus arteriosus can also lead to hemoptysis. Thus, the causes of hemoptysis are complex, and patients should pay sufficient attention to them and visit the hospital in time to get the correct diagnosis and effective treatment. 1. Once hemoptysis occurs, especially when the amount of hemoptysis is large, the patient should immediately go to a nearby hospital; 2. Avoid mental tension and mood swings to avoid aggravation of hemoptysis, rebleeding or recurrence of the disease; 3. Pay attention to keeping quiet and bed rest. When the amount of hemoptysis is large, the patient should choose to lie on the side toward the diseased lung so as to ensure normal ventilation of the healthy lung; 4. The patient can cough gently to cough out the blood clots deposited in the trachea. However, violent coughing should be avoided as much as possible, and appropriate cough suppressant and sedative medications can be taken if necessary. However, the elderly, weak and lung-incompetent should use these drugs with caution to prevent choking; 5. Otherwise, in order to hold the cough, the blood clot may block the trachea and cause asphyxia; 6. Hot and scalding drinks and foods may cause the blood vessels at the bleeding site to dilate, resulting in increased bleeding. Therefore, special attention should be given in daily life.