The symptoms of upper respiratory tract and lower respiratory tract infections are different, and there will be different symptoms due to the different sites of infection. The upper respiratory tract is mainly characterized by acute upper respiratory tract infection, which manifests itself as mild cough, coughing sputum, obvious nasal congestion, sneezing, runny nose, and even watery eyes, dizziness and weakness. The lower respiratory tract is mainly tracheitis, bronchitis and pneumonia, which may present with obvious cough, coughing sputum, chest tightness, chest pain, and even accompanied by wheezing and shortness of breath. In the case of purulent bacterial infection, a large amount of purulent sputum can be visibly seen coughing up, and the patient presents with relatively more pronounced dyspnea than in upper respiratory tract infections.