Before answering this question, it is important to clarify the concept of “interstitial pneumonia”. The term “interstitial pneumonia” is relatively popular, but not too specialized. Most people refer to the concept of interstitial pneumonia more accurately as “interstitial lung disease” or “diffuse substantive lung disease. This is because most people equate the interstitial changes described by chest CT with the technical terminology of “idiopathic interstitial pneumonia” or even “idiopathic pulmonary fibrosis (IPF)”. In essence, the interstitial changes expressed on CT at this time can be infections, tumors, cardiac insufficiency, systemic diseases, and of course, occupational, drug, etc. “Idiopathic interstitial pneumonia” is only one of these causes, while “idiopathic pulmonary fibrosis” is only one of them. “Idiopathic pulmonary fibrosis is one of the many types of idiopathic interstitial pneumonia. Therefore, for the sake of answering this question, I will refer to “idiopathic interstitial pneumonia” here (including later, if not specifically emphasized). The main symptoms are 1. dyspnea, which is obvious when moving, but most patients may not be particularly obvious at the beginning, gradually worsening, and in severe cases it is very difficult to turn over in bed; 2. cough, mostly dry, some patients may have a little white sputum; in case of co-infection there may be yellow thick sputum; 3. other rare symptoms, fever can be seen in cryptogenic mechanized pneumonia, acute interstitial pneumonia, acute exacerbation of IPF, etc.. Coughing up blood and pneumothorax are rare.