The most common reason for feet to swell is gravity. This is particularly true if you work in a job where you are on your feet all day. As you stand for extended periods of time, gravity pulls the fluids in your body toward your feet. As the fluids build up inside your feet, swelling can occur. Putting your feet up periodically during the day can help relieve and even prevent most cases of foot swelling from gravity.
Pregnancy
Pregnancy is another common reason why feet can swell. As the fetus grow inside the womb, there is an increase need for blood volume in the body to make up for the baby's presence. This increased blood volume can sometimes cause enough pressure on the arterial walls as to leak fluid out of the blood vessels and into the surrounding tissue in the feet and ankles.
Veins
Venous insufficiency may also cause feet to become swollen. Venous insufficiency occurs when the valves in your veins become weak. As a result, back pressure can occur in the veins causing blood to seep into the surrounding tissues. This is especially common for those suffering from varicose veins.
Secondary Symptom
Swelling of the feet may also be a secondary symptom of a more serious disorder. Congestive heart problems, emphysema, liver disease, kidney disease, bronchitis and thyroid disease all count swollen feet as a secondary symptom to their diagnosis.
