Pulmonary effusion in the elderly is more dangerous. A large amount of fluid in the pleural cavity can cause symptoms such as chest tightness and dyspnea, as well as aggravate existing underlying diseases. Due to the low immunity and poor physical quality of the elderly group, the treatment may be slow and ineffective, and it is easy to have complications or sequelae, resulting in an increased risk factor for the disease. Most of the causes of pleural effusion in the elderly are also more serious, such as tuberculous pleurisy, heart failure, lung tumors, etc., which increases the difficulty of treatment and results in a poor prognosis for patients. In conclusion, pulmonary effusion in the elderly is more dangerous, if not handled in time, can cause very serious complications, it is recommended that patients seek timely medical treatment, so as to avoid delaying the condition.