Swollen ankles can be a sign of something as simple as sitting too long or eating a salty meal, or they can point to a more serious condition like heart failure, kidney disease, or a blood clot. The key distinction is whether the swelling affects one ankle or both, how quickly it appeared, and whether other symptoms came with it.
Fluid naturally pools in the lowest parts of your body thanks to gravity. Your veins have one-way valves that push blood back up toward your heart, and your muscles act as pumps to help that process along. When something disrupts this system, whether it’s a failing organ, a damaged valve, or simply standing in one position for hours, fluid leaks out of small blood vessels and collects in the surrounding tissue. That buildup is called edema.
Heart, Kidney, and Liver Problems
When swelling shows up in both ankles and persists, it can reflect a problem with one of your major organs. In congestive heart failure, one or both of the heart’s lower chambers stop pumping blood effectively. Blood backs up in the legs, ankles, and feet, and fluid accumulates. This type of swelling often worsens throughout the day and improves overnight when you’re lying flat.
Kidney disease causes the body to retain extra fluid and salt, leading to edema that typically appears in the legs and around the eyes. A more specific form of kidney damage called nephrotic syndrome reduces protein levels in the blood, which makes it harder for your blood vessels to hold onto fluid. That fluid then leaks into surrounding tissues.
Liver damage from cirrhosis can also drive swelling in both the legs and the abdomen. When the liver can’t produce enough protein or process blood efficiently, fluid builds up in predictable places: the belly first, then the legs.
In all three cases, ankle swelling is rarely the only symptom. You’ll usually notice fatigue, shortness of breath, changes in urination, or unexplained weight gain alongside it. The swelling tends to develop gradually over days or weeks rather than appearing overnight.
Chronic Venous Insufficiency
One of the most common causes of persistent ankle swelling is a condition where the valves inside your leg veins stop working properly. These valves are designed to open when blood flows toward the heart and snap shut to prevent it from falling back toward the feet. Your legs have more of these valves near the ankles than near the thighs, specifically because gravity puts more pressure on the lower veins.
When the valves fail, blood flows backward (called reflux) and pressure builds in the lower leg. Normally, walking and calf movement drop the pressure inside your leg veins by more than 50%. With valve dysfunction, that pressure drop is blunted, and the veins refill rapidly instead of gradually. The result is chronic swelling, skin discoloration, and sometimes ulcers near the ankle. Up to 90% of people with chronic venous disease have reflux in their superficial veins.
Previous blood clots are a major cause of deep vein valve damage. Even after a clot resolves, the valves it damaged may never fully recover, leaving behind long-term swelling in that leg.
Blood Clots
Sudden swelling in one ankle or leg, especially with warmth, redness, or tenderness, is a warning sign of a deep vein thrombosis (DVT). This is the scenario that distinguishes one-sided swelling from two-sided swelling most urgently. A clot blocks blood from draining out of the leg, causing rapid fluid buildup on the affected side.
DVT requires prompt evaluation, typically with an ultrasound of the leg veins. If you notice one ankle becoming noticeably more swollen than the other over hours or a few days, particularly after a long flight, surgery, or a period of immobility, that asymmetry matters.
Pregnancy and Preeclampsia
Some ankle swelling during pregnancy is normal, driven by increased blood volume and pressure from the growing uterus on pelvic veins. But swelling that appears suddenly in the hands, ankles, and face after 20 weeks of pregnancy can signal preeclampsia, a serious condition involving high blood pressure and kidney stress.
Preeclampsia is defined by blood pressure above 140/90 mmHg along with protein in the urine. Early signs include rapid weight gain from fluid retention, swelling that seems out of proportion, headaches, and vision changes. Severe preeclampsia pushes blood pressure to 160/110 or higher and can threaten both the mother and baby. The swelling alone isn’t diagnostic, but combined with these other symptoms, it’s a red flag that needs immediate attention.
Medications and Lifestyle Factors
Several common medications cause ankle swelling as a side effect. Calcium channel blockers (used for blood pressure), certain diabetes drugs, steroids, and hormone therapies like estrogen can all promote fluid retention. If your swelling started shortly after beginning a new medication, that connection is worth raising with your prescriber.
High sodium intake is another frequent contributor. When you eat more salt than your body needs, the kidneys respond by holding onto extra water to keep your sodium concentration balanced. That extra fluid has to go somewhere, and gravity pulls it to your ankles and feet. Reducing sodium-heavy processed foods and restaurant meals often makes a noticeable difference within days.
Prolonged sitting or standing does the same thing mechanically. Without regular muscle contractions in the calves to pump blood upward, the veins in your lower legs fill and distend, and fluid seeps into the tissue. This is why ankles swell on long flights or during desk-bound workdays.
How to Tell if Swelling Is Significant
One quick way to assess ankle swelling is the pitting test: press a finger firmly into the swollen area for a few seconds, then release. If an indentation stays behind, that’s pitting edema. Clinicians grade it on a 1 to 4 scale based on how deep the pit is and how long it takes to bounce back:
- Grade 1: A shallow 2 mm pit that rebounds immediately
- Grade 2: A 3 to 4 mm pit that fills back in within 15 seconds
- Grade 3: A 5 to 6 mm pit that takes 15 to 60 seconds to rebound
- Grade 4: An 8 mm pit that persists for two to three minutes
Grade 1 after a long day on your feet is common and usually harmless. Grade 3 or 4 pitting, or any pitting that’s new and unexplained, suggests something beyond gravity and salt intake is going on.
Managing Mild Ankle Swelling
For swelling caused by lifestyle factors or mild venous issues, a few strategies help reliably. Elevating your legs above heart level for about 15 minutes, three to four times a day, lets gravity work in your favor and moves fluid back into circulation. Even propping your feet on a couple of pillows while watching TV makes a difference if your ankles are above your chest.
Compression stockings apply graduated pressure that supports your vein valves and prevents fluid from pooling. Low-compression stockings (under 20 mmHg) work for mild, occasional swelling. Medium compression (20 to 30 mmHg) is more effective for people with varicose veins or a history of blood clots. Higher levels, 30 to 40 mmHg and above, are reserved for severe swelling or chronic venous problems and typically require a fitting to ensure they work properly without cutting off circulation.
Regular movement is equally important. Walking, flexing your feet, or doing simple calf raises activates the muscle pump in your lower legs, which is the primary mechanism your body uses to push blood upward against gravity. Even short breaks from sitting every 30 to 60 minutes can prevent end-of-day swelling from developing in the first place.