Patients with pleural effusion prefer to lie on the affected side because when lying on the affected side, the pressure of the pleural effusion presses against the chest wall. If the patient is lying on the healthy side, the pleural fluid will compress the lungs and heart, which will aggravate the difficulty in breathing, so the patient prefers the affected side. This type of pleural effusion requires thoracentesis or closed chest drainage to reduce the pressure of the pleural effusion on the heart and lungs. In addition, the cause of the pleural effusion should be diagnosed and treated accordingly to cure it at the root. For example, if it is a tuberculous pleural effusion, regular anti-tuberculosis treatment should be given for one year to completely cure the tuberculous pleural effusion.