Coughing up yellow sticky sputum can be caused by upper respiratory tract infections, pneumonia, lung abscess, bronchiectasis and so on. 1. Upper respiratory tract infections: such as acute pharyngitis, acute tonsillitis, etc. will appear cough, cough yellow sticky sputum, sore throat, fever and other discomforts. 2. Pneumonia: especially Staphylococcus aureus pneumonia, Pseudomonas aeruginosa pneumonia, etc., which may cause cough, coughing of yellowish mucous sputum, fever and other symptoms. 3. Lung abscess, characterized by high fever, cough, and coughing up a large amount of yellow, sticky, purulent sputum, is an acute inflammation of the lungs caused by a variety of purulent bacteria. 4. Bronchodilatation combined with infection: fever, cough, cough yellow mucous sputum, hemoptysis as the main features, can also be accompanied by chest tightness, dyspnea and so on. Coughing yellow sticky sputum may also be caused by other factors, such as lung cancer combined with obstructive pneumonia, etc. Patients should consult the doctor in time to clarify the cause of the disease and get early treatment, so as to avoid delaying the condition.