After a pulmonary embolism, swelling in the legs can occur, and this situation is very likely secondary to right heart dysfunction following the pulmonary embolism. At this time, the main treatment should focus on the pulmonary embolism. The mechanism of pulmonary embolism mainly involves thrombi from the venous system, which travel with the blood flow to the right heart and then are lodged in the pulmonary artery, causing a sudden increase in the load on the right heart and leading to right heart failure. Consequently, the blood flow from the superior and inferior vena cava cannot return to the right heart. If the blood flow in the inferior vena cava is blocked peripherally, it can cause swelling in the legs. Therefore, the primary focus should still be on treating the underlying disease, by using anticoagulants or thrombolytic therapy. Swelling in the legs can also be alleviated with diuretics, but it is crucial not to move the lower limbs carelessly, as there might still be thrombi present, and moving the limbs could lead to the dislodgment of new thrombi.