Swollen feet, also called swelling of the lower extremities, generally occur for two main reasons. The first is cardiac insufficiency, and the second is renal insufficiency. Swelling of the lower extremities due to cardiac insufficiency is often accompanied by chest tightness, shortness of breath, panic attacks, and enlargement of the liver and spleen. In addition, edema gradually spreads upward from the feet. In contrast, edema in renal insufficiency first appears on the face and gradually spreads downward to the feet. Once the foot swelling appears, the patient should go to the hospital immediately and get systematic treatment through laboratory tests such as biochemistry and cardiac ultrasound to determine the cause of the foot swelling so that the patient can recover as soon as possible.