Patients with pulmonary effusion, i.e., fluid in the pleural cavity, often experience discomfort such as chest pain, cough, and dyspnea, in addition to other accompanying symptoms depending on the cause of the disease. Dyspnea is one of the most common clinical manifestations in patients with pleural effusion, and may be accompanied by chest pain and cough. Pleural effusion due to tuberculous pleurisy is often accompanied by low-grade fever, dry cough, chest tightness, shortness of breath and other discomforts. Malignant pleural effusion due to neoplastic disease, usually without fever, may be accompanied by emaciation, chest pain and other symptoms of tumor compression. Inflammatory pleural effusion caused by infectious diseases is often accompanied by obvious fever, chest pain, cough, sputum and other symptoms. Pleural effusion caused by heart failure is often accompanied by dyspnea, chest tightness, tiredness, fatigue, loss of physical strength and other signs of cardiac insufficiency. When patients have the above symptoms and suspect the presence of pleural effusion, it is recommended that they seek medical attention in time to avoid delaying their condition.