Coughing up black sputum with a cold may be associated with respiratory infections, pharyngitis, smoking or environmental irritants. 1. Respiratory tract infections, the most common cause, affected by viral infections, trachea and bronchial mucosa can be ruptured bleeding. If the bleeding is not coughed up immediately, it turns black for a long time, and is subsequently discharged along with sputum, which is manifested as black sputum. 2. Pharyngitis, inflammation in the throat can also cause bleeding, and the blood is discharged with the sputum, similar symptoms can also occur. 3. Smoking or environmental stimulation, smoking can lead to bronchial walls attached to tobacco substances, usually black, can cause black sputum symptoms; in a more polluted environment can also lead to similar performance. It is recommended to consult a doctor in time to clarify the cause of the disease, and at the same time, follow the doctor’s instructions for treatment.