Yellow, sticky sputum may be caused by acute pharyngolaryngitis, acute bronchitis or pneumonia. 1. Acute pharyngolaryngitis: usually caused by bacterial infection, resulting in the proliferation of lymphoid follicles in the wall of the pharynx, which causes pus in the pharynx, leading to an increase in pharyngeal secretions and the appearance of yellow, thick sputum. 2. Acute bronchitis: usually caused by bacterial infection, acute inflammation in the bronchial mucosa and its surrounding tissues, clinical symptoms can appear coughing and coughing sputum, yellowish and thick. 3. Pneumonia: usually due to infection with bacteria, viruses, mycoplasma and other adverse reactions, when the pathogenic bacteria repeatedly stimulate the human organism, there will be a frequent cough, cough sputum, phlegm, thick sputum, yellowish color symptoms. When yellowish and sticky sputum occurs, it is recommended to consult a doctor in time to clarify the cause of the disease with the help of the doctor and carry out targeted treatment or therapy.