Dark yellow sputum may be associated with lung infections, upper respiratory tract infections, lung abscesses, bronchiectasis, etc. It is recommended to go to the hospital for early diagnosis and treatment, and follow the doctor’s instructions for medication. Sputum is the liquid produced by the irritation of the respiratory tract, normal sputum is colorless, such as the occurrence of the above diseases can appear dark yellow sputum, in order to clarify the pathogenic bacteria need to be sent to the culture, and then based on the culture results to guide the treatment. 1. Pneumonia: fever, cough, sputum and other symptoms can occur, sputum can be yellow, red, green, serious cases can appear systemic inflammatory reaction, such as shortness of breath, high fever, heart rate increases, fatigue, drowsiness, etc., need to go to the hospital in a timely manner to the consultation, and comply with the doctor’s instructions to use medication. 2. Lung abscess: it can be manifested as fever, cough, cough yellow pus sputum, dyspnea, etc. The infection can migrate with the blood flow, which will lead to shock in severe cases. 3. Upper respiratory tract infection: Clinical manifestations may include sore throat, runny nose, fever, muscle pain, etc. If complicated by infection, deep yellow sputum may appear. 4. Bronchial dilatation: The typical symptoms of bronchial dilatation patients are chronic cough, coughing up a lot of pus sputum and repeated hemoptysis. Coughing dark yellow sputum may be caused by other reasons, such as acute exacerbation of chronic obstructive pulmonary disease, etc. It is recommended to go to the hospital, complete the examination, clarify the cause of the disease and diagnosis, and comply with the doctor’s instructions to standardize the treatment, so as to avoid delaying the condition.