Coughing up blood in colds may be caused by rupture of capillaries in the respiratory tract, and the possibility of coughing up blood caused by other diseases, such as tuberculosis, lung cancer, etc. should also be considered. 1. Respiratory capillary rupture: cold itself belongs to a very common disease, the disease will lead to the mucous membrane of the respiratory tract congestion and edema of the pathological manifestations, and in the case of severe coughing, the patient may be due to the rupture of the respiratory capillaries and coughing up blood, the general amount of blood is relatively small, or will only appear in the sputum with the condition of the blood. 2. Other diseases: Coughing up blood in patients with colds does not exclude the possibility of other comorbidities, such as tuberculosis, lung cancer, bronchodilatation and other respiratory diseases; there may be other organ lesions, such as congestive heart failure. Coughing up blood with a cold may also be due to other causes, and you should go to the hospital in time.