Pulmonary effusion due to pneumonia usually requires hospitalization for about 1 to 2 weeks. Pulmonary effusion is the colloquial term for an abnormal condition of increased fluid in the pleural cavity, which is generally referred to as pleural effusion in clinical practice. If the pneumonia is located close to the periphery of the pleural cavity, involvement of the pleura may result in pleural effusion. Usually the amount of pleural effusion caused by pneumonia is small, and after aggressive treatment, the pleural effusion is completely absorbed as the pneumonia is absorbed. The usual course of treatment for pleural effusion caused by pneumonia is about 1 to 2 weeks, and it can be completely cured after 1 to 2 weeks of hospitalization. Usually for young people and people with strong immune system, pleural effusion can be absorbed in about 1 week, but for old and weak people, it may take about 2 weeks to be completely cured. The number of days of hospitalization for pleural effusion depends on the condition of the patient, and other comorbidities should also be ruled out, so consult a medical professional for a comprehensive assessment.