Swollen feet and ankles usually mean fluid is collecting in the soft tissue of your lower legs, a condition called peripheral edema. In most cases, it’s caused by something temporary like sitting too long, eating a salty meal, or standing all day. But persistent or sudden swelling can signal a problem with your heart, kidneys, veins, or liver, so it’s worth understanding what your body might be telling you.
Fluid constantly moves between your bloodstream and the surrounding tissue. Your veins and lymphatic system work to push that fluid back up toward your heart. When something disrupts that balance, whether it’s gravity, inflammation, or a weakened organ, fluid pools in the lowest point it can find: your feet and ankles.
Common, Non-Serious Causes
The most frequent reason for puffy ankles at the end of the day is simply gravity. If you sit at a desk, stand in one spot, or take a long flight, blood flow slows in your lower legs and fluid seeps into the surrounding tissue. This type of swelling is usually equal in both legs, painless, and goes away after you elevate your feet for a while.
A high-sodium meal can also trigger temporary swelling. When you take in a lot of salt, your body holds onto extra water to keep your blood chemistry balanced. That extra fluid tends to settle in your feet and ankles first. Heat plays a similar role: warm weather causes blood vessels to widen, which lets more fluid leak into tissue. Pregnancy is another common cause, because the growing uterus puts pressure on the veins that return blood from the legs, and the body retains more fluid overall.
Heart, Kidney, and Liver Problems
When swelling doesn’t go away with rest and elevation, an underlying organ problem may be at play. Each of the body’s major filtration systems can cause fluid buildup when it starts to fail.
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. You may also notice swelling in the abdomen or fluid building up in the lungs, which causes shortness of breath when lying flat or during mild activity.
Kidney disease causes the body to hold onto extra fluid and salt. The swelling typically shows up in the legs and around the eyes. In a more specific form called nephrotic syndrome, the tiny filtering vessels in the kidneys become damaged and let too much protein escape into the urine. Low protein levels in the blood make it harder for fluid to stay inside the bloodstream, so it leaks out into tissue.
Liver damage from cirrhosis disrupts the organ’s ability to produce proteins that keep fluid in the blood vessels. This leads to swelling in the legs and a buildup of fluid in the abdomen known as ascites.
Chronic Venous Insufficiency
Your leg veins contain one-way valves that push blood upward toward your heart against gravity. When those valves become damaged, blood pools in the lower legs and pressure builds inside the veins. That increased pressure forces fluid out into the surrounding tissue, producing persistent ankle swelling.
Chronic venous insufficiency (CVI) is graded on a scale from 0 to 6 based on visible signs. Early stages involve spider veins and mild swelling. As it progresses, the skin may darken or become leathery, and severe cases can lead to scar tissue forming in the lower leg that traps fluid permanently. Open sores, or venous ulcers, can develop in the most advanced stage. CVI is more common in people who have had blood clots, who are overweight, or who spend long hours on their feet.
Medication Side Effects
Several widely prescribed medications can cause ankle swelling. Calcium channel blockers, a common class of blood pressure drugs, are one of the biggest culprits, with peripheral edema reported in up to 70% of people taking them. These drugs relax the walls of blood vessels, which increases the amount of fluid that leaks out of capillaries in the lower legs.
Anti-inflammatory painkillers (NSAIDs) like ibuprofen and naproxen cause the kidneys to retain sodium and water, which can worsen swelling. Certain diabetes medications, steroids, and hormone therapies can have the same effect. If your swelling started shortly after beginning a new medication, that’s worth flagging with whoever prescribed it.
When Swelling Affects Only One Leg
Bilateral swelling, meaning both legs are puffy, typically points to a systemic cause like heart failure, kidney disease, or medication effects. Swelling in just one leg is a different picture and raises concern for a blood clot.
Deep vein thrombosis (DVT) occurs when a clot forms in one of the deep veins of the leg. Symptoms include swelling, pain or cramping (often starting in the calf), skin that turns red or purple, and warmth over the affected area. Some DVTs produce no noticeable symptoms at all, which makes them particularly dangerous. The most serious complication is a pulmonary embolism, where the clot breaks free and travels to the lungs. Warning signs of that include sudden shortness of breath, chest pain that worsens with deep breaths, a rapid pulse, dizziness, or coughing up blood. This is a medical emergency.
Other causes of one-sided swelling include an injury, an infection, or a blockage in the lymphatic system. But sudden, unexplained swelling in a single leg warrants prompt evaluation.
Swelling During Pregnancy: Normal vs. Concerning
Some degree of ankle and foot swelling is completely normal during pregnancy, especially in the third trimester. But sudden swelling, particularly in the face and hands, can be a sign of preeclampsia, a serious condition involving high blood pressure and organ stress. Rapid, unexplained weight gain alongside that swelling is another red flag. Preeclampsia requires medical monitoring because it can progress quickly and affect both the mother and baby.
How Doctors Assess Swelling Severity
One of the first things a provider does is press a finger into the swollen area and observe what happens. If the pressure leaves an indentation that slowly fills back in, it’s called pitting edema. The depth of the pit and how long it takes to rebound determine the grade:
- Grade 1: A 2 mm pit that rebounds immediately. Mild.
- Grade 2: A 3 to 4 mm pit that rebounds in under 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 takes two to three minutes to fill back in. Severe.
Higher grades suggest more fluid accumulation and often prompt blood tests, imaging, or heart and kidney function assessments to find the underlying cause.
Reducing and Managing Swelling
For mild, occasional swelling, a few straightforward habits make a real difference. Elevating your legs above heart level for 15 to 20 minutes a few times a day lets gravity drain fluid back toward the center of your body. Moving regularly, even a short walk or calf raises at your desk, activates the muscle pump in your lower legs that helps push blood upward.
Sodium plays a direct role in fluid retention. For people with heart failure and fluid overload, guidelines from the American Heart Association recommend keeping sodium intake at or below 2,000 mg per day. Even without heart failure, cutting back on processed and restaurant foods (which account for most dietary sodium) can reduce swelling noticeably within a few days.
Compression Stockings
Compression stockings apply graduated pressure to your legs, tightest at the ankle and looser toward the knee, to help veins push blood upward. They come in several pressure levels measured in millimeters of mercury (mmHg):
- 15 to 20 mmHg (mild): Good for very early swelling, long flights, or prevention during extended standing.
- 20 to 30 mmHg (moderate): The most commonly prescribed level for mild to moderate edema and venous insufficiency.
- 30 to 40 mmHg (firm): Used for more significant swelling or when lower levels aren’t enough.
- 40 to 50 mmHg and above: Reserved for severe cases with significant tissue changes, typically after clinical assessment.
Starting with a moderate level is reasonable for most people dealing with everyday ankle swelling, but the right choice depends on what’s driving it.
Signs That Swelling Is an Emergency
Most foot and ankle swelling develops gradually and isn’t immediately dangerous. But certain combinations of symptoms mean the situation has become urgent. Swelling paired with sudden shortness of breath, wheezing or gasping, or coughing up pink or blood-tinged phlegm can indicate fluid in the lungs. This is a life-threatening condition that requires emergency care.
Similarly, chest pain or difficulty breathing alongside leg swelling could signal a pulmonary embolism. And swelling in one leg with redness, warmth, and calf pain suggests a possible blood clot that needs same-day evaluation. Persistent swelling that worsens over days or weeks, even without dramatic symptoms, still deserves a medical workup to rule out heart, kidney, or liver issues before the problem progresses.