Swollen ankles and feet happen when excess fluid collects in the tissues of your lower legs, pulled there by gravity and held there by one of several underlying problems. The medical term is peripheral edema, and its causes range from sitting too long on a flight to serious conditions like heart failure or blood clots. Understanding what’s behind the swelling helps you figure out whether it’s something you can manage at home or something that needs medical attention.
How Fluid Ends Up in Your Feet
Your body constantly moves fluid between your bloodstream and the surrounding tissues. This exchange depends on a balance of pressures inside and outside your blood vessels. Swelling occurs when that balance tips in one of five ways: pressure inside the blood vessels rises too high, the protein levels that keep fluid inside your veins drop too low, the walls of your blood vessels become too leaky, the lymphatic system that drains excess fluid gets blocked, or the fluid outside the vessels pulls in more water than it should.
Because your feet and ankles are the lowest point in your body, gravity makes them the first place fluid accumulates. That’s why swelling tends to worsen through the day and improve overnight when you’re lying flat.
Heart and Circulation Problems
Heart failure is one of the most common serious causes of ankle swelling, particularly when the right side of the heart weakens. When the heart can’t pump blood forward efficiently, blood backs up in the veins that return it from your legs. The increased pressure forces fluid out of the blood vessels and into the surrounding tissue, where it collects as visible swelling in the ankles, feet, and lower legs. You may also notice weight gain from retained fluid or swelling in the abdomen.
Heart failure symptoms tend to develop gradually. Early on, you may notice mild puffiness in the evening that resolves by morning. As the condition progresses, the swelling becomes more persistent and harder to ignore. It’s often accompanied by shortness of breath, fatigue, and difficulty lying flat at night.
Chronic Venous Insufficiency
Your leg veins contain one-way valves that push blood upward toward the heart. When those valves weaken or fail, blood pools in the lower legs, a condition called chronic venous insufficiency. The sustained high pressure in the veins causes fluid to leak out into surrounding tissues, producing swelling that typically worsens with standing or sitting for long periods.
Left untreated, venous insufficiency progresses through recognizable stages. It often starts with spider veins or varicose veins, then advances to persistent edema. Over time, the skin around the ankles can darken, thicken, or develop a leathery texture. In severe cases, open sores (venous ulcers) form near the ankle and can be slow to heal. The condition is far easier to manage in its earlier stages.
Kidney and Liver Disease
Your kidneys regulate how much sodium and water your body retains. When kidney function declines, the kidneys hold on to excess sodium, and water follows. The result is fluid retention throughout the body, but it shows up most noticeably in the feet, ankles, and around the eyes.
Liver disease, particularly cirrhosis, causes swelling through a different path. A damaged liver produces less albumin, the protein in your blood that acts like a sponge to keep fluid inside your vessels. When albumin drops, fluid escapes into surrounding tissues. At the same time, cirrhosis triggers a hormonal chain reaction: the body ramps up production of hormones that tell the kidneys to retain even more sodium and water. This double mechanism explains why people with advanced liver disease often develop severe swelling in the legs alongside fluid buildup in the abdomen.
Pregnancy and Preeclampsia
Some swelling during pregnancy is completely normal. The growing uterus puts pressure on the veins returning blood from the legs, and pregnancy hormones cause the body to retain more fluid. Mild ankle puffiness, especially in the third trimester, affects most pregnant women and is not a cause for alarm.
The situation changes when swelling is sudden, severe, or accompanied by high blood pressure. Preeclampsia is a pregnancy complication that typically develops after 20 weeks and is defined by new-onset high blood pressure (140/90 or higher) along with signs of organ stress. Generalized, rapid-onset swelling can be one of its features. Other warning signs include severe headaches, vision changes, and intense pain in the upper abdomen or below the breastbone, particularly at night. Up to 50 percent of women initially diagnosed with elevated blood pressure alone during pregnancy eventually develop full preeclampsia, so any new hypertension in the second half of pregnancy warrants close monitoring.
Medications That Cause Swelling
Several widely prescribed medications list ankle swelling as a side effect. Calcium channel blockers, commonly used to treat high blood pressure, are among the most frequent culprits. These drugs relax blood vessel walls, which can increase fluid leakage into the tissues. Depending on the specific drug, ankle swelling occurs in roughly 1 to 15 percent of people taking them.
Other medications that commonly cause fluid retention include corticosteroids (like prednisone), anti-inflammatory painkillers such as ibuprofen and naproxen, certain diabetes medications, and some hormone therapies including estrogen. If your swelling started or worsened after beginning a new medication, that connection is worth discussing with your prescriber. In many cases, an alternative drug or dosage adjustment can resolve the problem.
When Swelling Signals a Blood Clot
Most ankle swelling affects both legs roughly equally. Swelling in just one leg is a different story and raises concern for a deep vein thrombosis (DVT), a blood clot in the deep veins of the leg. Along with one-sided swelling, DVT often causes warmth, redness, and tenderness along the path of the affected vein. The calf of the swollen leg may measure noticeably larger than the other side.
Certain factors significantly increase DVT risk: active cancer, recent surgery, prolonged bed rest or immobilization (including a leg cast), and long periods of sitting such as on a flight or road trip. A blood clot in the leg can break free and travel to the lungs, creating a life-threatening pulmonary embolism. If you develop sudden, unexplained swelling in one leg, especially with pain or skin color changes, seek medical evaluation promptly.
Everyday Causes and Lifestyle Triggers
Not all ankle swelling points to a medical condition. Spending long hours on your feet, sitting at a desk all day, or eating a high-sodium meal can all produce noticeable puffiness by evening. Hot weather dilates blood vessels near the skin surface, allowing more fluid to seep into tissues. Tight clothing or shoes that restrict circulation can contribute as well.
Excess body weight increases pressure in the leg veins and makes it harder for fluid to return to the heart. Even modest weight loss can improve chronic swelling in people who are overweight.
Managing Swelling at Home
For mild, occasional swelling without an underlying medical condition, a few practical strategies make a real difference.
Elevate your legs. Position them above heart level for about 15 minutes, three to four times a day. Lying on a couch with your feet propped on pillows or the armrest works well. This lets gravity work in your favor, helping fluid drain back toward the heart.
Watch your sodium. The American Heart Association recommends staying under 1,500 mg of sodium per day for the general population. For context, a single fast-food meal can exceed that limit. Reading labels and cooking more meals at home are the most reliable ways to cut back. People with heart failure are typically advised to stay under 2,000 mg daily.
Try compression stockings. Over-the-counter options at 15 to 20 mmHg provide mild support and work well for everyday swelling, long flights, or jobs that require standing. If your swelling is related to venous insufficiency or lymphatic issues, a 20 to 30 mmHg stocking (often labeled “moderate” or Class I) is the most commonly recommended daytime level. Higher pressures of 30 to 40 mmHg are available but should be fitted based on a clinical assessment.
Move regularly. Walking activates the calf muscles, which act as a pump to push blood back up through the leg veins. If you sit for long stretches, flexing your ankles or taking short walking breaks every hour helps prevent fluid from pooling.
Persistent swelling that doesn’t improve with elevation, swelling that leaves a lasting dent when you press on it, or swelling accompanied by shortness of breath, chest pain, or skin changes all point toward a cause that needs professional evaluation rather than home management alone.