Patients with blood inside the cough are mainly considered to have the following aspects: 1. Patients can cough violently due to various etiologies, causing damage to the tracheal mucosa and thus appearing with blood in the sputum. 2. It can be seen in some patients with lung infections, such as in patients with tuberculosis, pneumonia and lung abscess, which can be accompanied by blood in the sputum. 3. When bronchial dilatation is acutely aggravated, some patients can also often appear with 4. For patients with long-term cough with blood in the sputum, especially long-term smokers, attention should be paid to the exclusion of bronchial lung cancer. 5. Some patients with severe pharyngitis can also have cough with blood in the sputum. In conclusion, blood in the sputum when coughing is mostly caused by bronchial and pulmonary diseases. Patients should improve relevant examinations early, especially lung CT and bronchoscopy, in order to clarify their causes.