There are many different causes of swollen feet with low-grade fever in the elderly. The more common causes are heart failure and inflammation of the legs, which can cause swelling of the feet and can be accompanied by a low-grade fever. Severe liver disease that prevents blood from entering the liver directly and leads to increased venous pressure in the lower extremities can also cause swelling of both lower extremities. In patients with severe kidney disease, swelling of all parts of the body may occur, which can also cause swelling of the legs of both lower limbs. For example, patients with acute and chronic nephritis, nephrotic syndrome, and reduced glomerular filtration function leading to sodium and water retention, these conditions may also cause swelling of the legs of both feet. Also, hypothyroidism and venous lesions of both lower extremities may cause edema. In elderly people with swollen feet and hypothermia, this condition requires prompt examination at a hospital to diagnose and treat the cause after clarification.