The most common cause of coughing up blood is infectious diseases of the respiratory system, such as colds, acute pharyngitis, acute tracheitis and bronchitis, and severe coughing caused by lung infections, which may destroy capillaries and cause bleeding, along with symptoms such as weakness, loss of appetite, and general malaise. Bronchiectasis may also cause coughing and blood in the sputum, and may generally cause life-threatening hemoptysis, so prompt medical attention is needed, often accompanied by coughing and coughing up yellow pus sputum. Tuberculosis can also be seen as coughing and blood in sputum, usually accompanied by low fever in the afternoon, hot flashes, night sweats, weight loss, fatigue and other symptoms, and can also be seen in malignant tumors of the lung, coughing and hemoptysis, commonly seen in people over 40 years of age who smoke, often accompanied by weight loss, fatigue, coughing, wheezing, chest tightness and so on. Coughing and bleeding can also be seen in the oral cavity. Bleeding in the oral cavity, such as gingivitis and bleeding gums, will be coughed out through coughing, and will also be accompanied by localized swelling of the gums, pain, bad breath, etc. Of course, there is also nasal bleeding, which can be caused by various reasons, such as nasal bleeding flowing backwards into the mouth and pharynx, and can be coughed out by coughing.