Swollen ankles result from fluid accumulating in the tissues around your ankle joint, and the causes range from something as simple as standing too long to serious conditions involving your heart, kidneys, or blood vessels. Most cases involve fluid being pushed out of your blood vessels and into surrounding tissue, a process driven by gravity, inflammation, or pressure changes inside your veins. Understanding what’s behind the swelling helps you figure out whether it’s a temporary nuisance or something that needs medical attention.
Vein Problems and Poor Circulation
The most common chronic cause of ankle swelling is a condition called chronic venous insufficiency, which affects about 1 in 20 adults. Your leg veins contain one-way valves that push blood back up toward your heart against gravity. When those valves weaken or stop closing properly, blood pools in your lower legs and fluid leaks into the surrounding tissue. The swelling tends to worsen as the day goes on and improve overnight when your legs are elevated.
Over time, venous insufficiency can cause more than just puffiness. You might notice skin discoloration around your ankles, a brownish or reddish tint that develops gradually. In more advanced cases, the skin can break down into open sores called venous ulcers. If your ankles swell regularly and you see color changes in the skin, a painless vascular ultrasound can show whether your vein valves are damaged.
Blood Clots in the Leg
A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the calf or thigh. It typically causes swelling in only one leg, along with pain or cramping that often starts in the calf, warmth over the affected area, and skin that turns red or purple. This is a key difference from most other causes of ankle swelling, which tend to affect both legs equally.
DVT can also occur without noticeable symptoms, which is part of what makes it dangerous. The clot can break loose and travel to the lungs, causing a pulmonary embolism. If one ankle swells suddenly, especially after surgery, a long flight, or a period of immobility, and the skin feels warm or looks discolored, that warrants urgent evaluation.
Medications That Cause Swelling
Several common medications trigger ankle swelling as a side effect, and blood pressure drugs called calcium channel blockers are among the most frequent culprits. These medications work by relaxing blood vessel walls, but they relax arteries more than veins. That imbalance increases pressure inside the tiny capillaries of your lower legs, forcing fluid out into surrounding tissue. The effect is dose-dependent: higher doses cause more swelling.
When another type of blood pressure medication (an ACE inhibitor or ARB) is added alongside a calcium channel blocker, the swelling drops significantly. One analysis found that combining these drug classes reduced the rate of ankle swelling by 38% and cut the number of people who had to stop their medication due to swelling by 62%. Other medications that commonly cause ankle edema include certain diabetes drugs, steroids, hormone replacement therapy, and some antidepressants. If your ankles started swelling after a new prescription, that timing is worth mentioning to your prescriber.
Heart, Kidney, and Liver Conditions
When your heart can’t pump blood efficiently, fluid backs up in your veins and settles in your ankles and feet. Heart failure is one of the more serious causes of bilateral ankle swelling, and the puffiness often comes with other signs: shortness of breath, fatigue, and difficulty lying flat at night. The swelling tends to be symmetrical and may extend up the shins.
Your kidneys filter excess fluid from your blood, so when they aren’t working well, that fluid has nowhere to go. Kidney disease causes swelling that often shows up in both the ankles and around the eyes, particularly in the morning. Liver disease, especially cirrhosis, reduces your body’s production of a blood protein that helps keep fluid inside your vessels. Without enough of this protein, fluid leaks out and collects in the legs and abdomen.
Pregnancy and Hormonal Changes
Some ankle swelling during pregnancy is completely normal, especially in the third trimester. The growing uterus puts pressure on the veins returning blood from the legs, and hormonal shifts cause your body to retain more fluid. Mild, symmetrical swelling that comes and goes is expected.
What isn’t normal is sudden, severe swelling in the hands and face after 20 weeks of pregnancy. This pattern can signal preeclampsia, a condition defined by high blood pressure (140/90 mmHg or above) and protein spilling into the urine. Other warning signs include persistent headaches, visual disturbances like blurred vision or seeing spots, and upper abdominal pain. Preeclampsia affects both the mother and baby and requires prompt medical management.
Outside of pregnancy, hormonal fluctuations during the menstrual cycle can cause mild fluid retention that shows up in the ankles. This type of swelling is cyclical, predictable, and resolves on its own.
Injuries and Inflammation
A sprained ankle is one of the most obvious causes of localized swelling. When ligaments stretch or tear, inflammation floods the area with fluid as part of the healing response. This swelling is usually one-sided, painful, and clearly linked to a specific injury. Fractures, tendon injuries, and infections in the foot or ankle produce similar localized swelling.
Arthritis, particularly rheumatoid arthritis and gout, can also cause ankle swelling. Gout tends to strike suddenly with intense pain, redness, and swelling, often in one joint at a time. Rheumatoid arthritis produces more gradual, symmetrical swelling and stiffness that tends to be worst in the morning.
Lifestyle and Environmental Factors
Prolonged sitting or standing lets gravity do its work. Fluid naturally migrates downward, and without the muscle contractions of walking to pump blood back up through your veins, it accumulates around your ankles. Long flights, desk jobs, and standing shifts are common triggers. Hot weather compounds the effect because heat causes blood vessels to dilate, allowing more fluid to seep into tissue.
High salt intake increases the amount of fluid your body retains, and that extra fluid tends to settle in the lowest points. Excess body weight also contributes by increasing venous pressure in the legs. These lifestyle-related causes typically produce mild, symmetrical swelling that resolves with movement and elevation.
How to Tell If Swelling Is Mild or Serious
A simple way to gauge severity is the “pitting” test. Press your thumb firmly into the swollen area for a few seconds, then release. If the indentation bounces back almost immediately, the swelling is mild. If a visible dent lingers for 15 seconds, it’s moderate. Severe edema leaves an indentation that takes 30 seconds or more to fill back in. Tracking how quickly the pit rebounds gives you a useful reference point to share with a provider.
Swelling that affects both ankles equally, worsens with standing, and improves with elevation is more likely related to gravity, medications, or a systemic condition. Swelling in one leg only, especially with warmth, pain, or skin color changes, raises concern for a blood clot or infection. Swelling that appears suddenly alongside shortness of breath, chest pain, or reduced urine output points toward a heart or kidney problem that needs prompt attention.
Reducing Ankle Swelling at Home
Elevating your legs above heart level for 15 to 20 minutes several times a day helps gravity drain fluid back toward your core. Regular walking activates the calf muscles, which act as a pump to push blood upward through your veins. Reducing salt intake lowers the amount of fluid your body holds onto.
Compression stockings apply graduated pressure that supports your veins and prevents fluid from pooling. Low-compression stockings (under 20 mmHg) work for mild, occasional swelling. Medium compression (20 to 30 mmHg) is the most commonly recommended range for persistent edema, and clinical evidence shows that stockings in the 15 to 20 mmHg range produce significant improvement compared to no compression. Higher-pressure stockings (30 to 40 mmHg or above) are reserved for more advanced venous problems and are typically fitted with professional guidance.
These measures help manage symptoms, but they don’t replace identifying the underlying cause. Swelling that persists for more than a few days, keeps getting worse, or appears alongside other symptoms is worth investigating rather than just managing at home.