How long it takes for a pleural effusion to heal depends on the cause of the disease and the patient’s specific situation, and cannot be generalized. There are many causes of pleural effusion, and the recovery time varies from disease to disease. If it is caused by tuberculosis, it requires standardized anti-tuberculosis treatment, and the recovery time is more than six months. If it is caused by post-surgery, the patient can recover within a month with a small amount of water. If it is caused by bacterial infection, the inflammation needs to be actively controlled, and the inflammation can be improved quickly after control. If the pleural effusion is caused by malignant tumor, it is prone to recurrence. If only thoracentesis is performed to extract the fluid, it can be produced again soon and can be treated by instilling chemotherapy drugs into the chest cavity, and it has the possibility of getting better, but the chances are small, and the overall prognosis is poor with a short survival period. Regardless of the cause of pleural effusion, if the amount of effusion is large and causes compression, active drainage of the pleural effusion is needed to improve the patient’s compression symptoms.