Swollen ankles and feet happen when fluid builds up in the tissue beneath your skin, a condition called edema. The causes range from something as simple as sitting too long or eating a salty meal to serious conditions involving your heart, kidneys, or veins. Whether one foot is swollen or both can tell you a lot about what’s going on.
How Fluid Ends Up in Your Feet
Your body constantly moves water between your bloodstream and the surrounding tissue. Pressure inside your blood vessels pushes fluid out, while proteins in your blood pull it back in. Your lymphatic system acts as a cleanup crew, draining whatever excess slips through. Swelling happens when fluid leaks out faster than your body can reabsorb or drain it.
Gravity plays a major role. Because your feet and ankles sit at the lowest point of your body, fluid naturally pools there when any part of this balancing system breaks down. That’s why swelling tends to worsen through the day and improve overnight when you’re lying flat.
One Leg vs. Both: Why It Matters
Swelling in just one ankle or foot usually points to a local problem. The most urgent concern is a blood clot in a deep vein, known as DVT, which typically causes swelling, warmth, and pain in one leg. This needs immediate medical attention because the clot can travel to your lungs. When DVT is ruled out in cases of one-sided swelling, about 40% of the time the cause turns out to be a muscle strain, tear, or twisting injury. Other single-leg causes include infections, a fluid-filled cyst behind the knee (Baker’s cyst), or blocked lymph drainage.
Swelling in both ankles and feet is more likely tied to something systemic, meaning a condition affecting your whole body. Chronic venous disease is the most common cause of long-standing bilateral swelling. Heart failure, kidney disease, liver disease, and certain medications round out the list.
Chronic Venous Insufficiency
This is one of the most frequent explanations for persistent ankle swelling, affecting about 1 in 20 adults. Your leg veins contain one-way valves that push blood upward toward your heart. When those valves weaken or become damaged, gravity wins, and blood flows backward and pools in your lower legs. The sustained pressure forces fluid out of the veins and into the surrounding tissue.
Over time, you may notice skin changes around your ankles: darkening pigmentation, thickened or hardened skin, and in advanced cases, open sores that are slow to heal. The swelling tends to be worst at the end of the day and improves when you elevate your legs. Risk factors include a history of blood clots, prolonged standing, obesity, and pregnancy.
Heart, Kidney, and Liver Problems
When your heart can’t pump blood efficiently, pressure builds in the veins leading back from your legs. At the same time, reduced blood flow to the kidneys triggers them to retain extra fluid in an attempt to boost circulation, which only makes the swelling worse. This creates a cycle: the heart struggles, the kidneys hold onto fluid, and the legs and abdomen swell further. Other signs of heart-related swelling include fatigue, shortness of breath, and difficulty with physical activity.
Kidney disease causes swelling through a different route. Damaged kidneys lose their ability to filter waste and remove excess fluid from the blood. They may also leak protein into the urine, which lowers the concentration of protein in your bloodstream. Since blood proteins help pull fluid back into your vessels, losing them lets fluid seep into tissue throughout your body, often showing up first in the feet, ankles, and around the eyes.
Liver disease, particularly cirrhosis, reduces your liver’s production of those same blood proteins. It also raises pressure in the veins that drain from the abdomen, which backs up into the legs. Swelling from liver disease often appears alongside a noticeably distended abdomen.
Medications That Cause Swelling
Several common medications can trigger ankle and foot swelling as a side effect. Blood pressure drugs in the calcium channel blocker family are frequent culprits. Hormone therapies, including estrogen and testosterone, can promote fluid retention. Some diabetes medications, anti-inflammatory drugs like ibuprofen and naproxen, and certain antidepressants also make the list. If your swelling started shortly after beginning a new medication, that timing is worth mentioning to your prescriber. Stopping or switching the drug often resolves the problem.
Swelling During Pregnancy
Some degree of ankle swelling is considered normal during pregnancy, especially in the third trimester. Your body produces significantly more blood and fluid to support the baby, and the growing uterus puts pressure on the veins returning blood from your legs.
The concern is when swelling signals preeclampsia, a serious pregnancy complication. Normal pregnancy swelling tends to be mild and concentrated in the ankles. Preeclampsia swelling is more likely to appear in the hands, arms, or face, often with noticeable, rapid weight gain from fluid retention. The defining features of preeclampsia are a blood pressure reading of 140/90 or above and protein in the urine, though it can occasionally occur without the protein. Severe preeclampsia pushes blood pressure to 160/110 or higher and may bring on headaches, vision changes, abdominal pain, or reduced urine output.
Salt, Inactivity, and Other Everyday Triggers
Not all ankle swelling points to a medical condition. A high-sodium diet is one of the most common and fixable causes. Salt makes your body hold onto water, and that extra fluid tends to settle in your feet and ankles. Current guidelines from the Heart Failure Society of America recommend keeping sodium under 2,000 to 3,000 milligrams per day, with a stricter limit of under 2,000 milligrams for people with moderate to severe heart failure. For context, a single fast-food meal can easily contain over 2,000 milligrams.
Prolonged sitting or standing keeps your calf muscles from pumping blood back up toward your heart. Long flights, desk jobs, and standing shifts all contribute. Heat also plays a role, as warm temperatures cause blood vessels to widen, allowing more fluid to leak into surrounding tissue. Being overweight adds pressure to the veins in your legs and pelvis, making it harder for blood to return efficiently.
How Doctors Evaluate Swelling
When you press a swollen area and a dent stays behind for a few seconds, that’s called pitting edema. Doctors grade it on a four-point scale based on how deep the dent goes and how long it takes to bounce back. A grade 1 pit is just 2 millimeters deep and rebounds immediately. Grade 4 leaves an 8-millimeter pit that takes two to three minutes to fill back in. Higher grades generally suggest more significant fluid overload.
Beyond the physical exam, testing depends on what your doctor suspects. If a blood clot is a concern, an ultrasound of the leg veins is the standard next step. For suspected heart involvement, blood tests and imaging of the heart help assess how well it’s pumping. Kidney and liver function show up on routine blood panels. When poor circulation in the arteries is a possibility, a simple pressure test comparing blood pressure at the ankle to the arm can screen for blockages.
Reducing Swelling at Home
Elevating your legs above the level of your heart is the simplest way to encourage fluid to drain. Aim for about 15 minutes at a time, three to four times a day. Lying on a couch with your feet propped on a couple of pillows or resting against a wall works well.
Compression socks apply gentle, graduated pressure that helps push blood and fluid upward. They’re especially useful if you stand or sit for long periods. Cutting back on sodium, staying hydrated (which actually helps your body release retained fluid rather than hold it), and moving throughout the day all make a meaningful difference. Even brief walks or flexing your feet while seated activates the calf muscles that act as pumps for your veins.
These strategies work well for mild, occasional swelling. If the swelling is new and persistent, affects only one leg, comes with pain or redness, or is accompanied by shortness of breath or chest discomfort, those patterns suggest something that needs medical evaluation rather than home management.