Swollen ankles happen when fluid builds up in the tissue around your ankle joint, and the causes range from harmless to serious. The underlying problem is almost always the same: fluid that normally stays inside your blood vessels leaks out into surrounding tissue, or fluid that should drain away gets trapped. What matters is figuring out why that’s happening, because some causes resolve on their own while others need prompt attention.
How Fluid Ends Up in Your Ankles
Your body constantly moves fluid between your bloodstream and the tissue around it. Four things can tip that balance and cause swelling: increased pressure inside your blood vessels (from standing all day or a heart that isn’t pumping efficiently), low protein levels in your blood (which normally act like a sponge keeping fluid inside your vessels), leaky blood vessel walls (from inflammation or infection), or a blocked drainage system (when lymph channels can’t carry fluid away).
Gravity pulls fluid downward, which is why ankles and feet swell before anywhere else. If you press a finger into the swollen area and it leaves a visible dent, that’s called pitting edema. Doctors grade it on a 1 to 4 scale based on how deep the dent is and how long it takes to bounce back. A grade 1 pit is about 2 millimeters deep and rebounds immediately. A grade 4 pit is 8 millimeters deep and can take two to three minutes to fill back in.
Everyday Causes That Aren’t Dangerous
The most common reason for ankle swelling is simply spending too long on your feet or sitting with your legs down. Long flights, desk jobs, and standing shifts all increase pressure in your lower leg veins. The swelling typically goes down overnight when you’re lying flat. Hot weather makes it worse because your blood vessels widen to release heat, allowing more fluid to seep out.
High sodium intake is another frequent culprit. Salt causes your body to hold onto water, and that extra fluid has to go somewhere. The American Heart Association recommends staying under 1,500 milligrams of sodium per day, though most people consume well over double that amount. Cutting back on processed foods, canned soups, and restaurant meals can make a noticeable difference in ankle swelling within days.
Medications That Cause Ankle Swelling
Certain blood pressure medications are one of the most common drug-related causes. Calcium channel blockers, a widely prescribed class of blood pressure drugs, cause ankle swelling in 1 to 15 percent of people taking standard doses. At higher doses taken long-term, that number can climb above 80 percent. Common examples include amlodipine, nifedipine, and felodipine. The swelling happens because these drugs relax blood vessel walls, letting more fluid leak into surrounding tissue.
Other medications that can cause ankle swelling include anti-inflammatory painkillers (like ibuprofen and naproxen), certain diabetes drugs, steroids, and some hormone therapies including estrogen. If your ankles started swelling after beginning a new medication, that connection is worth raising with whoever prescribed it. Stopping or switching the drug often resolves the problem, but don’t make changes on your own.
Heart Failure
When your heart can’t pump blood efficiently, it backs up in your veins. That increased pressure forces fluid out of your blood vessels and into your tissues, collecting in your lungs, legs, feet, and abdomen. Heart failure is a long-term condition, and swollen ankles are one of its hallmark signs.
The key distinction is that heart failure rarely shows up as ankle swelling alone. You’d typically also notice shortness of breath (especially when lying down or waking up at night), fatigue during physical activity, a dry hacking cough, heart palpitations, weight gain from fluid retention, and needing to urinate more often at night. If ankle swelling comes alongside any of these symptoms, that combination warrants prompt medical evaluation.
Chronic Venous Insufficiency
Your leg veins have one-way valves that push blood upward against gravity. When those valves weaken or fail, blood pools in your lower legs instead of returning to your heart. This is chronic venous insufficiency, and it’s extremely common, particularly as people age or after pregnancies.
Early on, you might notice your legs feeling achy, heavy, or tired, especially by the end of the day. Visible spider veins or varicose veins often appear. As the condition progresses through six clinical stages, swelling becomes persistent, skin near the ankles may darken or thicken, and in advanced cases, open sores called venous ulcers can develop. A burning or “pins and needles” sensation in the legs is another characteristic sign. Compression stockings, regular walking, and elevating your legs are the main ways to manage it.
Kidney Problems
Your kidneys filter your blood and regulate how much fluid and protein stay in your body. When they’re damaged, they can leak large amounts of a protein called albumin into your urine. Albumin normally works like a sponge inside your blood vessels, pulling fluid in and keeping it there. When albumin levels drop, fluid seeps out into your tissues, causing swelling that often starts in the ankles and feet and can spread to the face and hands.
This pattern of protein loss is called nephrotic syndrome, and the swelling it causes tends to be soft, widespread, and worse in the morning (particularly around the eyes) before shifting to the legs later in the day. Foamy urine is another telltale sign, caused by excess protein.
Blood Clots: When One Ankle Swells
A deep vein thrombosis, or DVT, is a blood clot that forms in a deep vein, usually in the leg. This is one of the more urgent causes of ankle swelling, because a clot can break loose and travel to the lungs.
The critical clue is that DVT almost always affects one leg. If only your left or right ankle is swollen, and it came on relatively quickly, pay attention. Other signs include pain or cramping that often starts in the calf, skin that looks red or purple, and warmth over the swollen area. That said, DVT can also occur without noticeable symptoms, which is why risk factors matter. Recent surgery, long periods of immobility (like a hospital stay or long flight), cancer, pregnancy, and use of hormonal birth control all increase your risk.
Bilateral swelling, where both ankles are equally puffy, is far more likely to come from a systemic cause like heart failure, kidney disease, or medication side effects. One-sided swelling that’s painful and warm should be evaluated urgently.
Pregnancy and Preeclampsia
Mild ankle swelling during pregnancy is normal, especially in the third trimester. Your body retains more fluid, your growing uterus puts pressure on pelvic veins, and blood volume increases significantly. This type of swelling is usually worse at the end of the day and improves with rest and elevation.
The concern is when swelling appears suddenly or severely, because it can signal preeclampsia. This is a serious pregnancy complication defined by blood pressure reaching 140/90 or higher along with protein in the urine. Severe preeclampsia involves blood pressure of 160/110 or above, or signs of organ damage. Other warning signs include persistent headaches, vision changes, upper abdominal pain, and nausea. Preeclampsia can develop even without protein in the urine, so sudden dramatic swelling during pregnancy always deserves a call to your provider.
Liver Disease
Your liver produces albumin, the same protein your kidneys are supposed to keep from leaking away. When the liver is severely damaged, as in advanced cirrhosis, it can’t make enough albumin. The result is the same: low protein levels in your blood mean fluid escapes into your tissues. Ankle swelling from liver disease often comes alongside a swollen, fluid-filled abdomen, yellowing of the skin, and easy bruising.
What the Pattern of Swelling Tells You
Paying attention to a few details can help narrow down the cause before you ever see a doctor. Swelling in both ankles that’s worse at the end of the day and better in the morning points toward venous insufficiency, prolonged standing, or medication effects. Both ankles swelling along with shortness of breath or fatigue suggests a heart or kidney issue. One swollen ankle that came on quickly, with pain and warmth, raises concern for a blood clot or injury. Swelling that leaves a deep, slow-to-rebound pit generally means more fluid has accumulated and the underlying cause may be more significant.
Tracking when the swelling started, whether it’s getting worse, and what other symptoms accompany it gives you the most useful information to bring to a medical visit. Even a smartphone photo comparing your ankles at the end of the day versus the morning can be genuinely helpful for your provider.