Why Do You Have Swollen Feet and Ankles?

You slip on your workday flats in the morning with ease, but by closing time you look down at swollen feet with dismay. Puffy skin has mushroomed upward and beyond the confines of your shoes. Any definition between your bloated ankles and calves has disappeared. Pressing fingertips into your skin leaves indentations that only sluggishly fade. At night, you prop your aching feet on an ottoman or piled-up pillows. The next day you wake with normal feet and slender ankles -- but by evening, once again, your lower legs are thick and swollen from instep to knee. What gives?

[See: 10 Seemingly Innocent Symptoms You Shouldn't Ignore.]

Everyday Edema

When the body retains excess fluid in the calves, ankles and feet, it's known as edema. Gravity is the culprit, says Dr. Vinod Kumar, a vascular specialist and medical director of Vascular Health, an institute for comprehensive cardiac and vascular care in Bakersfield, California.

With healthy circulation, veins carry the blood away from the lower legs and up to the heart. But prolonged sitting or standing tests the body's ability to maintain upward blood flow. If the heart's pumping is weak or if valves in the leg veins don't close properly, excess blood pools and swelling results, starting at the lowest point in the body.

"In the morning hours when you wake up it's fine, because there's no gravity," Kumar says. "But as you sit or stand long hours, by evening you start seeing more [swelling] and feeling that kind of heaviness or something tight. Some people even feel burning. You feel kind of tired." Almost 10 percent of adults experience lower-leg swelling by day's end, he says. Jobs that involve prolonged sitting or standing can lead to swelling. Travel with long car rides or airplane flights can also trigger it.

Underlying Causes

Swelling doesn't affect people equally. Obesity and aging make it more likely. Surgery is another cause, especially when recovery involves immobility. Certain medications can provoke swelling, too, as can sprains, twists and other injuries.

Many women retain fluid during their menstrual cycles, which can cause general swelling. Taking estrogen may also contribute. While swelling is common during pregnancy, in some cases it can signal preeclampsia, a maternal condition involving high blood pressure with potentially serious health implications.

Varicose veins -- swollen, twisted veins just beneath the skin's surface -- are not only unsightly but can cause swelling. "In varicose veins, the valves do not fully close -- or become incompetent -- thereby some of the blood comes back down," Kumar explains. "Typically, patients find a lot of relief when they lie in their beds with their feet up higher so that the blood moves along with gravity back toward the heart." Some patients opt for a vein ablation procedure, in which the incompetent vein is sealed. Blood no longer flows back to the feet and swelling is gone.

Medical conditions such as congestive heart failure and kidney disease put added stress on the blood vessels, leading to swelling. Swollen legs and feet can indicate worsening heart failure, liver disease or gout. Conditions known as chronic venous insufficiency and iliac vein compression syndrome -- or incompetent leg veins, more simply -- have a strong, direct swelling effect. Clotting is a potential complication.

"If blood is sluggish and not flowing well, it tends to clot," Kumar says. "Some patients we see come to the emergency room with blood clots in their legs." Other signs of a blood clot, or deep vein thrombosis, include redness, heat or warmth to the touch, pain that gets worse when bending the foot, discolored skin and leg cramps.

"I'd be concerned if it's unilateral leg swelling as opposed to both legs swelling," says Dr. Linda Girgis, a family medicine physician in South River, New Jersey. That, she notes, could signal a clot.

[See: 17 Ways Heart Health Varies in Women and Men.]

Compressed Veins

Already coping with Type 1 diabetes, Sandy Mendoza didn't need another chronic health issue. But about 10 years ago, her calves, feet and ankles began to swell. Eventually, "my calves looked as big as my thighs," the Bakersfield, California, resident recalls.

Mendoza's legs were bruised and discolored and she experienced painful, burning sensations. Her left foot developed an ulcer that became infected and required treatment with antibiotics. Her condition gradually escalated until she could barely bend her legs to walk. She could only "sit-stand" by leaning on a countertop or other surface for support.

Last year, Mendoza's physician referred her to Kumar for an evaluation. He found that pressure on the pelvis was blocking her iliac veins -- the main veins that carry blood from the legs back up to the heart. In October, Mendoza underwent a stent-insertion procedure on her right leg to clear the blockage, prop open the vein and keep the blood flowing in the right direction. Several weeks later, she was back in the catheterization lab for the same procedure in her left leg.

While Mendoza still requires dialysis to manage the kidney disease she developed as a result of her diabetes, she has stopped taking pain medication and is no longer homebound. About a month ago she was happy to return to the gym, where she carefully works out to build up strength in her legs. Her family is planning a previously undoable theme-park trip. "I can walk," she says. "I'm not stuck in a chair all day. Which is just amazing." Another perk of surgery: She's dropped a shoe size.

[See: 5 Ways to Reduce Your Risk of Developing Kidney Disease.]

Troubleshooting Swelling

Most people won't need surgery to eliminate or reduce uncomfortable foot swelling. For some, the solution may lie within their medicine cabinets (swelling is a side effect of many prescription medications). The blood pressure drug amlodipine is one example. In those cases, Kumar says, health providers can easily make a substitution.

Patients tend to try common-sense measures at home before consulting their doctors, Girgis says. "When it becomes painful or gets worse, that's when they usually come to me."

Along with leg elevation, Girgis recommends avoiding prolonged standing, drinking more fluids and wearing compression stockings, or support hosiery. "A lot of people are resistant," she admits. "First, I try to convince them it's a good idea to wear them for a limited time because it helps push back all the fluid."

Soaking in Epsom salt, considered a home remedy for foot and leg swelling, isn't backed by evidence, Girgis says. "If somebody tries and it makes them feel better, there's no real harm in doing that either," she says. "But it's not something I actively recommend."

Weight-bearing exercise like walking is helpful, she says, and swimming, which promotes gentle movement, is another good idea. If Girgis suspects electrolyte imbalances, like a magnesium deficiency, are contributing to swelling, blood tests can uncover the problem. Nutritional supplements, if indicated, may reduce the bulge. Losing weight improves mobility and reduces swelling, and following a lower-sodium, heart-healthy diet can help people feel better overall.

Lisa Esposito is a Patient Advice reporter at U.S. News. She covers health conditions, drawing on experience as an RN in oncology and other areas and as a research coordinator at the National Institutes of Health. Esposito previously reported on health care with Gannett, and she received her journalism master's degree at Georgetown University. You can follow her on Twitter, connect with her on LinkedIn or email her at lesposito@usnews.com.