If there is a change from excessive sputum to no sputum, then it may be an improvement, but if there is no sputum in itself, then it is not possible to judge whether it is an improvement or not. In case of lung infection, chronic obstructive pulmonary disease, etc., the patient may have a lot of sputum in the acute stage of infection, sticky, not easy to cough out, etc., and the sputum gradually disappears in the course of treatment until it becomes sputum-free, which is generally an improvement phenomenon. It represents the control of lung infection and the gradual recovery of trachea and bronchial mucosa damage. However, if the sputum itself is not present, such as tuberculosis, cough variant asthma and so on. Therefore, it is not possible to judge whether the disease has improved based solely on the absence of sputum, but also need to refer to other symptoms, test results, such as cough significantly reduced, lung function significantly improved. Therefore, it is recommended to consult a doctor in a timely manner to determine the severity of the disease after relevant examinations under the guidance of the doctor.