Swollen ankles result from fluid building up in the tissues around your ankle joint, and the causes range from standing too long at work to serious conditions like heart failure or blood clots. About 1 in 5 Americans over age 55 have persistent lower limb swelling, making it one of the most common health complaints in older adults. The key to figuring out your situation is whether the swelling affects one ankle or both, how quickly it appeared, and what other symptoms came with it.
Prolonged Standing or Sitting
The most common and least worrisome cause of swollen ankles is simply being on your feet or sitting in one position for too long. When you stand for hours, gravity increases the pressure inside your leg veins, pushing fluid out of the bloodstream and into the surrounding tissue. Sitting creates a different but related problem: low muscle activity in your calves reduces the pumping action that normally pushes blood and lymph fluid back up toward your heart, and pressure from the chair seat on the backs of your thighs can slow drainage further.
This type of swelling is typically mild, affects both ankles equally, and goes away after you elevate your legs or move around. People in jobs that require long shifts on their feet, or those who sit at a desk or on a plane for hours, are most likely to notice it. If the swelling consistently disappears overnight and returns during the day, positional fluid buildup is the likely explanation.
Chronic Venous Insufficiency
Your leg veins contain one-way valves that keep blood flowing upward toward your heart. When those valves become damaged, blood pools in the lower legs, increasing pressure inside the veins and forcing fluid into surrounding tissues. This condition, called chronic venous insufficiency, is one of the most common causes of persistent ankle swelling.
The swelling tends to be worst at the end of the day or after long periods of standing. Over time, it often comes with other telltale signs: a burning or tingling sensation in the legs, nighttime leg cramps, reddish-brown discoloration of the skin, and a heavy or full feeling in the calves. In severe cases, the trapped fluid causes scar tissue to form in the lower leg, making the calf feel hard to the touch. Left unmanaged, venous insufficiency can eventually lead to skin ulcers near the ankle.
Heart, Kidney, and Liver Disease
When ankle swelling appears on both sides and doesn’t fully resolve with leg elevation, it can signal a problem with one of the body’s major organ systems. Each one causes swelling through a slightly different mechanism, but the end result is the same: excess fluid leaking into the tissues of your lower legs.
Heart failure, particularly when the right side of the heart is involved, raises the pressure in your veins. Blood backs up in the legs because the heart can’t pump it forward efficiently. This is one of the most common causes of sudden worsening of bilateral ankle swelling, and it often comes with shortness of breath, fatigue, or rapid weight gain from fluid retention.
Kidney disease causes swelling differently. Healthy kidneys filter excess sodium and water out of your blood. When they lose that ability, fluid accumulates throughout the body. In nephrotic syndrome specifically, the kidneys leak protein into the urine, which lowers the concentration of protein in your blood. That protein normally acts like a sponge, holding fluid inside your blood vessels. Without enough of it, fluid seeps into your tissues.
Liver cirrhosis works through that same protein mechanism. A damaged liver can’t produce enough of the blood proteins that keep fluid in the bloodstream, so it migrates into the surrounding tissue. Liver disease also raises pressure in the veins that drain the abdomen, which backs up fluid into the legs.
Medications That Cause Swelling
Several widely prescribed medications list ankle swelling as a side effect, and it’s worth checking your medication list before assuming something more serious is going on. The most frequent culprits are calcium channel blockers used for high blood pressure, particularly amlodipine, nifedipine, and felodipine. These drugs widen blood vessels, which can increase fluid leakage into tissues.
Other medications associated with ankle swelling include:
- NSAIDs (ibuprofen, naproxen), which cause the kidneys to retain sodium and water
- Hormone therapies containing estrogen or testosterone
- Nerve pain medications like gabapentin and pregabalin, with swelling reported in roughly 7.5% of people taking higher doses of gabapentin
- Acid reflux medications (omeprazole, lansoprazole, pantoprazole), a less well-recognized cause
- Pioglitazone, a diabetes medication that very commonly causes fluid retention
If your ankle swelling started within a few months of beginning a new medication, that timing is a strong clue. In many cases, switching to a different drug in the same class resolves the problem.
Ankle Injuries
A sprained or fractured ankle causes localized swelling from inflammation, and it typically affects only the injured side. Ankle sprains are graded by severity. A mild (grade 1) sprain stretches the ligament without significant tearing, and you can usually still walk on it. A moderate (grade 2) sprain involves a partial tear with noticeable swelling and pain during movement. A severe (grade 3) sprain means the ligament is completely torn, producing significant swelling that may make walking impossible.
Injury-related swelling is usually obvious because it follows a specific incident, like rolling your ankle. But stress fractures and overuse injuries can cause more gradual swelling that’s easy to mistake for other causes, especially if you don’t remember a clear moment of injury.
Pregnancy-Related Swelling
Mild ankle swelling is extremely common during pregnancy, especially in the third trimester. The growing uterus puts pressure on the veins that return blood from the legs, and hormonal changes cause the body to retain more fluid. This type of swelling is usually harmless.
The concern is when swelling appears suddenly or severely after 20 weeks of pregnancy, because it can be a sign of preeclampsia. Preeclampsia is defined by new-onset high blood pressure (140/90 or above) along with protein in the urine or signs of organ stress. Generalized, rapid-onset edema is listed among its clinical findings. Severe preeclampsia involves blood pressure readings of 160/110 or higher and requires immediate medical attention. The swelling alone isn’t diagnostic, but when it comes on quickly and is accompanied by headaches, vision changes, or upper abdominal pain, it warrants urgent evaluation.
Blood Clots in the Leg
A deep vein thrombosis (DVT) is a blood clot that forms in one of the deep veins of your leg, and it is one of the more dangerous causes of ankle swelling. The hallmark of DVT is that the swelling is almost always unilateral, meaning it affects only one leg. If one ankle is noticeably more swollen than the other, especially if that leg is also warm, red, or painful, a blood clot needs to be considered.
DVT is a medical emergency because the clot can break free and travel to the lungs, causing a pulmonary embolism. Risk factors include recent surgery, long periods of immobility (like a long flight), cancer, and use of hormonal birth control. Doctors typically use a combination of clinical scoring systems and ultrasound imaging to confirm or rule out a clot.
In rare cases, blood clots can form in both legs at once, particularly in people with underlying cancer. So bilateral swelling doesn’t completely eliminate DVT as a possibility, though it makes it far less likely.
Managing Mild Ankle Swelling
For swelling caused by positional factors, venous insufficiency, or medication side effects, a few practical strategies can make a meaningful difference. Elevating your legs above the level of your heart for 15 to 20 minutes several times a day helps fluid drain back toward your core. Regular walking or calf exercises activate the muscle pump in your lower legs, which pushes blood upward through your veins.
Compression stockings apply graduated pressure to the legs, with the tightest compression at the ankle and lighter pressure further up. They come in low (under 20 mmHg), medium (20 to 30 mmHg), and high (over 30 mmHg) pressure ratings. Stockings below 20 mmHg are available over the counter for mild swelling, while anything rated 20 mmHg or higher requires a prescription and should be fitted based on your specific condition.
Reducing sodium intake is commonly recommended, though the relationship between salt and swelling is more nuanced than many people realize. In people with healthy kidneys, high sodium intake raises the volume of fluid in the bloodstream but doesn’t necessarily increase total body water or cause visible edema on its own. The effect is more pronounced when kidney function is impaired or when other causes of swelling are already present. In those situations, excess sodium makes existing swelling worse by causing the kidneys to hold onto more water.