The yellow sputum with blood may be a result of a violent cough, causing the rupture of small blood vessels and coughing up blood. Yellow sputum suggests infection of the lungs, and the common causative agents are Streptococcus pneumoniae, Staphylococcus aureus, and Pseudomonas aeruginosa. The most common disease of coughing up yellow sputum with blood is bronchiectasis, which can be manifested as repeated yellow sputum, and because of the abnormal capillary network in the lungs, the bronchial accompanying blood vessels are highly susceptible to rupture, leading to repeated hemoptysis or even hemoptysis, which may be life-threatening or even asphyxiating. In addition, if the infection in the lung is combined with the rupture of small blood vessels in the nose and mouth, blood in sputum may also occur. Therefore, if you have yellow sputum with blood, you need to go to the hospital for a chest X-ray or chest CT examination and, if necessary, a visit to the department of quintessential medicine or stomatology to clarify the cause.