What causes my legs and feet to swell?

Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
If you've suddenly found yourself shopping for wider or larger shoes, you may want to take a better look at the reasons why. If your shoes no longer fit, this could be a sign of edema, a swelling of the feet, ankles and legs caused by excess fluid trapped in your body's tissues. This may present itself as what people more commonly recognize as "cankles," or calf-ankles.

Mild cases can be caused by sitting or staying in one position for too long, or consuming too much salt. However, in more serious cases, edema can be an indicator of something more serious: heart failure (the heart loses its ability to pump blood effectively and blood backs up in your legs); severe liver disease (compromised liver function causes changes in the way your body regulates fluids); or kidney disease (when the kidneys can not eliminate enough fluid and sodium from your blood).
Howard E. Lewine, MD
I assume that both your feet are swollen. This is important to note because new swelling in just one foot can be caused by a blood clot in the leg or by an injury to the foot or ankle. When both feet are swollen, the cause is almost always fluid retention in the legs.

The most common reason for swelling in both feet is "incompetent" valves in the leg veins. The leg veins return blood to the heart after the blood has delivered oxygen and nutrients to the foot and lower leg.

Unlike the arteries, the veins can't rely on the pumping action of the heart to move the blood in the right direction. The veins need the valves to stop blood from backing up. Many people have malfunctioning vein valves. This can cause back pressure in the veins, which leads to fluid leaking out of the bloodstream and into the feet. Often varicose veins are seen.

Other reasons for swelling in both feet include:
  • Heart conditions, specifically heart failure
  • Severe lung disease
  • Kidneys that are not functioning normally
  • Anemia
  • Malnutrition
  • An underactive or overactive thyroid gland
Usually there will be other symptoms with the above health problems, not just swollen feet.

You can decrease your swelling by wearing support stockings. You can also elevate your feet above the level of your heart whenever you sit down. Your doctor may prescribe a low-dose water pill (diuretic) if you still cannot control the swelling.
Harvard Medical School Foot Care Basics: Preventing and treating common foot conditions

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.