There are many reasons for coughing up yellow sputum and runny nose, such as upper respiratory tract bacterial infection, nasal diseases, viral infections and so on. 1. Bacterial infection of the upper respiratory tract: Bacterial infection of the upper respiratory tract can be characterized by runny nose, nasal congestion, sneezing, etc. Bacterial infection can also cause coughing up yellow sputum, accompanied by headache, fever, cough and other phenomena. 2. Nasal diseases: chronic rhinitis, allergic rhinitis, sinusitis can lead to nasal mucosal congestion, edema, increased secretion, can be accompanied by nasal itching, sneezing and other phenomena, resulting in coughing up yellow sputum runny nose. 3. Viral infections: coughing up yellow sputum and running clear mucus may also be due to viral infections, accompanied by the phenomenon of fever, need to carry out sputum culture, blood routine to clarify the diagnosis. After the emergence of symptoms, you need to go to the hospital in a timely manner, after a clear diagnosis of the choice of standardized treatment, do not take the treatment, so as not to lead to adverse consequences!