Swollen feet and ankles are usually caused by fluid pooling in the lower legs, a condition called edema. Gravity pulls excess fluid downward throughout the day, and your feet and ankles sit at the lowest point. The cause can be as simple as sitting too long or eating a salty meal, or it can signal something more serious like heart, kidney, or liver problems. Understanding the pattern of your swelling, whether it affects one leg or both, and what other symptoms come with it helps narrow down what’s going on.
The Most Common Everyday Causes
For many people, swollen ankles come down to lifestyle and habits rather than a serious medical condition. Long, unbroken periods of sitting or standing are among the most frequent triggers. When your leg muscles stay inactive, they can’t help pump blood back up toward your heart, so fluid settles into your ankles and feet. This is why swelling often worsens on long flights, during road trips, or after a full day at a desk or on your feet at work.
A high-sodium diet is another major contributor. Foods like chips, canned soup, processed meats, cheese, and fast food cause your body to hold onto more water than it needs. That extra fluid has to go somewhere, and it tends to accumulate in the lowest parts of your body. Alcohol overuse can have a similar effect. For most people in these categories, the swelling is temporary and improves with movement, elevation, and dietary changes.
Medications That Cause Swelling
Certain blood pressure medications, specifically calcium channel blockers, are well-known for causing ankle swelling. The effect is dose-related: at lower doses, ankle swelling occurs in roughly 1 to 15% of patients, but at high doses taken long-term, the rate can exceed 80%. If you take one of these medications and notice your ankles puffing up, that connection is worth raising with your prescriber. Combining a calcium channel blocker with another type of blood pressure drug can reduce the likelihood of swelling by about 38%.
Other drug classes that commonly cause fluid retention include anti-inflammatory painkillers (like ibuprofen and naproxen), certain diabetes medications, steroids, and some hormone therapies including estrogen. If your swelling started around the same time you began a new medication, the timing is a strong clue.
Vein Problems and Chronic Venous Insufficiency
When the valves inside your leg veins weaken or stop working properly, blood doesn’t flow back to the heart efficiently. It pools in the lower legs instead. This condition, called chronic venous insufficiency, is one of the most common causes of persistent ankle swelling, especially in older adults and people who have had blood clots in the past.
The swelling typically starts right around the ankle bones and creeps up the leg over time. It gets worse with standing and improves when you put your feet up. Beyond swelling, you may notice a heavy, aching feeling in your legs, visible varicose veins, and eventually skin changes: darkened or discolored patches near the ankles, dry or itchy skin, and in advanced cases, thickened or hardened skin on the lower leg. Left untreated, it can progress to open sores that are slow to heal.
Heart, Kidney, and Liver Conditions
When swelling affects both legs and doesn’t go away with rest and elevation, it can point to a problem with one of your major organs. Each one causes fluid buildup through a different mechanism, but the result looks similar from the outside.
In heart failure, the heart can’t pump blood forward efficiently, so pressure builds in the veins and pushes fluid out into surrounding tissues. The ankles and feet swell first because gravity directs the backup downward. You might also notice shortness of breath, fatigue, or waking up at night needing to catch your breath.
Kidney disease reduces your body’s ability to filter out excess salt and water. Instead of leaving through urine, that fluid accumulates in your tissues. Liver disease, particularly cirrhosis, disrupts circulation in a more complex way. The liver’s blood vessels become scarred and resistant to flow, which triggers a chain reaction: the kidneys respond by holding onto more salt and water, expanding total fluid volume. The swelling in liver disease often comes alongside a visibly distended abdomen.
Thyroid disease and sleep apnea are two other chronic conditions that can contribute to persistent swelling in the lower legs, though they’re less commonly recognized as culprits.
Swelling in One Leg Is Different
If only one foot or ankle is swollen, the cause is almost always local rather than systemic. The most urgent possibility is a deep vein thrombosis, or blood clot, in the leg. A DVT typically causes swelling in one leg along with pain or cramping that often starts in the calf, warmth over the affected area, and a change in skin color to red or purple. This combination needs prompt medical evaluation because a clot can break loose and travel to the lungs.
Other causes of one-sided swelling include a sprained ankle or other injury, an infection like cellulitis, or a blockage in the lymphatic system. Lymphedema, where the body’s drainage system is damaged or overwhelmed, creates a distinctive type of swelling. In its early stages it may look like regular puffiness, but over time the skin becomes thicker and firmer. A classic sign is that you can’t pinch the skin on top of your second toe into a fold. Lymphedema is typically painless but progressive, and it can affect one or both legs.
Swelling During Pregnancy
Some swelling in the feet and ankles is completely normal during pregnancy, especially in the third trimester. Your body carries significantly more blood volume, and the growing uterus puts pressure on the veins returning blood from your legs.
What’s not normal is sudden swelling, particularly in the face and hands, or a rapid jump in weight over a few days. These can be signs of preeclampsia, a serious pregnancy complication involving high blood pressure. If swelling comes on quickly or is accompanied by headaches, vision changes, or upper abdominal pain, that warrants immediate attention.
How to Tell Pitting From Non-Pitting Edema
You can learn something useful by pressing a finger firmly into the swollen area for about five seconds. If it leaves a visible dent that slowly fills back in, that’s called pitting edema. This type is associated with fluid that has a low protein concentration and is common in heart failure, kidney problems, vein issues, and medication side effects.
If the skin feels firm or doughy and doesn’t hold an indentation, that’s non-pitting edema, which is more characteristic of lymphedema or thyroid disease. One exception: early-stage lymphedema can still pit, so a dent doesn’t automatically rule it out.
What Helps Reduce the Swelling
The most effective home strategies target gravity and fluid movement. Elevating your legs above the level of your heart, even for 15 to 20 minutes a few times a day, helps fluid drain back toward your core. At night, placing a pillow under your calves can keep swelling from building up while you sleep.
Compression socks apply graduated pressure that supports your veins and prevents fluid from pooling. For mild everyday swelling, 15 to 20 mmHg is usually sufficient. Moderate swelling from varicose veins or post-surgical recovery typically calls for 20 to 30 mmHg. Higher levels (30 to 40 mmHg and above) are used for chronic venous insufficiency and severe lymphedema but generally need a professional fitting. Most people wear compression during the day and remove them for sleep.
Reducing sodium intake makes a noticeable difference for many people. Moving your legs regularly, even just flexing your ankles or taking short walks, activates the calf muscles that act as pumps to push blood upward. Staying physically active and maintaining a healthy weight both reduce the load on your circulatory system over time.
What a Doctor Will Check
If your swelling is persistent, worsening, or accompanied by other symptoms like shortness of breath, chest pain, or skin changes, a medical workup can identify the underlying cause. Doctors typically start with a physical exam, looking at things like whether the swelling pits, whether pulses in your feet are strong, whether there’s tenderness or warmth, and whether the skin shows signs of venous disease.
Basic blood and urine tests can check how well your heart, kidneys, and liver are functioning, along with your protein levels. If a blood clot is suspected, an ultrasound of the leg veins is the standard next step. For chronic swelling with skin changes, your doctor may evaluate your venous system more closely to look for valve problems. In most cases, a thorough history, physical exam, and a handful of lab tests are enough to point to the right diagnosis.