What causes swollen feet Swollen feet may be caused by physiological reasons or due to kidney disease, heart failure, varicose veins of the lower extremities, trauma and other reasons. 1. Physiological: It may be caused by long standing and sitting for a long time which leads to the decrease of venous return of the lower limbs, resulting in the occurrence of swollen feet. 2.Pathologic: (1) Kidney diseases: such as glomerulonephritis, chronic nephritis and other causes. The decrease in plasma colloid osmotic pressure may be caused by the decrease in glomerular filtration rate or the decrease in albumin, which in turn causes the occurrence of swollen feet. (2) Heart failure: a complex clinical syndrome caused by multiple etiological factors resulting in structural or functional damage to the heart, decreased filling or ejection capacity of the heart, and bruising or ischemia of organs and tissues. Decreased pumping capacity of the right heart and accumulation of blood can occur, leading to decreased return of blood from peripheral veins, and edema in the sagging area will be observed, progressing gradually upward from the ankles. (3) Varicose veins of the lower limbs: This may be caused by prolonged standing, low activity of the lower limbs, and venous valve insufficiency. It may appear that blood from deep veins flows back to superficial veins. And superficial vein blood cannot enter deep vein in time, which leads to elevated venous pressure, venous stasis, and blood leakage from varicose veins into the tissue interstitial space, which can lead to leg swelling. (4) Sports injuries such as trauma can also lead to swollen and painful feet. Swollen feet can also be seen in other diseases, it is recommended to seek timely medical attention to clarify the cause and early treatment.