Causes Of Swollen Feet

This is usually a temporary nuisance caused by standing too long  or a long flight -- especially if you are pregnant. In contrast, feet that stay swollen can be a sign of a serious medical condition. The cause may be poor circulation, a problem with the lymphatic system, or a blood clot. A kidney disorder or underactive thyroid can also cause swelling. If you have persistent swelling of your feet, see a physician.