Swollen ankles for no reason and no pain refers to ankle swelling without pain, common causes are physiological phenomena, kidney disease, right heart failure. 1. Physiological phenomenon: due to long squatting, long standing lack of exercise, resulting in lower extremity blood microcirculation obstruction, blood reflux obstacles, can cause ankle swelling, is a normal phenomenon. 2. Kidney disease: If you suffer from chronic renal failure, nephrotic syndrome and other diseases, which cause a decrease in the filtration capacity of the kidneys, a decrease in the amount of urine or a large amount of protein loss in the urine, resulting in hypoproteinemia, ankle swelling can occur. 3. Heart disease: such as right heart failure, due to right ventricular dysfunction, resulting in increased venous pressure in the circulation, can also cause ankle swelling. The causes of ankle swelling without pain are more reasons, may also be related to lower extremity venous thrombosis, hyperthyroidism, cirrhosis, diabetes mellitus complications and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in a timely manner, to clarify the cause of the disease, and targeted treatment.