Swollen feet and ankles result from fluid leaking out of tiny blood vessels and collecting in surrounding tissue. The causes range from sitting too long on a flight to serious conditions like heart failure or blood clots. About 20% of adults over 50 experience this kind of swelling, making it one of the most common reasons people visit a doctor. Whether the swelling affects one leg or both, came on suddenly or built up over weeks, tells you a lot about what’s behind it.
Everyday Causes That Resolve on Their Own
Not all foot and ankle swelling signals a medical problem. Sitting or standing in one position for hours, especially during long flights or desk-bound workdays, lets gravity pool fluid in your lower legs. Eating a particularly salty meal can do it too: when your body takes in more sodium than it needs, it holds onto extra water to keep things balanced. Premenstrual hormonal shifts cause the same kind of temporary fluid retention.
These cases typically resolve once you move around, sleep with your legs slightly elevated, or cut back on salt. If your swelling disappears overnight and comes back predictably with certain habits, lifestyle is the most likely explanation. Keeping daily sodium intake between 1,500 and 2,300 milligrams can make a noticeable difference for people who regularly retain fluid.
Chronic Venous Insufficiency
The most common medical cause of persistent foot and ankle swelling is chronic venous insufficiency, a condition where the valves inside your leg veins stop working properly. Healthy veins push blood back up toward the heart against gravity, with one-way valves preventing backflow. When those valves weaken or fail, blood pools in the lower legs, pressure builds inside the veins, and fluid seeps into surrounding tissue.
More than 25 million adults in the United States have varicose veins, and over 6 million have more advanced venous disease. Prevalence rises sharply with age: roughly 21% of men and 12% of women over 50 have clinically significant venous insufficiency. You might notice swelling that worsens throughout the day and improves after a night of sleep, along with aching, heaviness, or visible varicose veins. Over time, the skin around your ankles can darken or become leathery. About 20% of people with chronic venous insufficiency eventually develop venous ulcers, open sores that are slow to heal.
Heart, Kidney, and Liver Disease
When swelling appears in both feet and ankles and doesn’t go away, an organ system may be struggling. Each of the three major organs involved in fluid balance can produce edema through a different mechanism.
In congestive heart failure, one or both of the heart’s lower chambers lose pumping strength. Blood backs up in the veins, raising pressure in the legs and forcing fluid into tissue. The swelling tends to worsen over the course of the day and may be accompanied by shortness of breath, fatigue, or rapid weight gain from retained fluid.
Kidney disease reduces your body’s ability to filter excess sodium and water, so fluid accumulates. Liver cirrhosis lowers the production of a key blood protein that normally holds fluid inside blood vessels. Without enough of that protein, fluid leaks out more easily and collects in the legs and abdomen. In all three cases, the swelling is usually bilateral and develops gradually over weeks or months.
Medications That Cause Swelling
A surprisingly long list of common medications can trigger foot and ankle swelling. Blood pressure drugs in the calcium channel blocker class are among the most frequent culprits. The reported rate of ankle swelling ranges from 1% to 15% at standard doses, but at higher doses taken long-term, that number can exceed 80%. The swelling happens because these drugs widen blood vessels, which increases pressure in the small capillaries of the feet and lets fluid leak out.
Other medications known to cause edema include:
- Anti-inflammatory drugs: both over-the-counter pain relievers like ibuprofen and prescription corticosteroids
- Nerve pain medications: gabapentin and pregabalin
- Hormones: estrogen, progesterone, and testosterone
- Certain beta blockers used for blood pressure or heart rate
- Diabetes medications in the thiazolidinedione class
If your swelling started within weeks of beginning a new medication, that timing is worth mentioning to your prescriber. Medication-related edema often resolves once the dose is adjusted or the drug is switched.
Blood Clots: When One Leg Swells
Sudden swelling in just one leg is the hallmark of deep vein thrombosis, a blood clot forming in a deep vein, usually in the calf or thigh. Along with swelling, you may notice pain or cramping that starts in the calf, skin that looks red or purple, and warmth over the affected area. DVT is the most common cause of acute, one-sided leg swelling.
The real danger is that a clot can break loose and travel to the lungs, causing a pulmonary embolism. Warning signs include sudden shortness of breath, chest pain that gets worse when you breathe deeply or cough, a rapid pulse, dizziness, or coughing up blood. A pulmonary embolism is a medical emergency. If you have new one-sided leg swelling with pain that doesn’t resolve, especially after a period of immobility like surgery or a long flight, seek medical evaluation promptly.
Pregnancy-Related Swelling
Some ankle swelling during pregnancy is completely normal and expected. The body produces roughly 50% more blood and fluid to support the baby, and the growing uterus puts pressure on veins returning blood from the legs. Most pregnant women notice puffiness in their feet and ankles, particularly in the third trimester.
The concern is preeclampsia, a pregnancy complication involving high blood pressure that affects about 5% to 8% of pregnancies. The key difference: normal pregnancy swelling stays around the ankles, while preeclampsia often causes swelling in the hands, arms, or face, along with greater-than-expected weight gain from fluid retention. Blood pressure readings of 140/90 or higher and protein in the urine are the diagnostic markers. Severe preeclampsia can cause headaches, vision changes, upper abdominal pain, and difficulty breathing. A woman with mild preeclampsia may not notice any symptoms at all, which is why routine prenatal blood pressure checks matter.
Lymphedema and Lipedema
When the lymphatic system, your body’s drainage network, becomes damaged or blocked, fluid backs up in the tissue and causes a distinctive type of swelling called lymphedema. It can result from surgery (especially lymph node removal during cancer treatment), radiation, infection, or it can develop without a clear cause. The swelling tends to feel heavy and tight, the skin may harden over time, and pressing on it creates a slow, memory-foam-like indentation. In advanced cases, the limb becomes visibly misshapen. Severity is graded by how much the limb grows: mild lymphedema means less than 20% increase in size, moderate is 20% to 40%, and severe exceeds 40%.
Lipedema is a different condition that’s often confused with lymphedema. It involves an abnormal buildup of loose, spongy fat in the limbs, almost always in both legs symmetrically. A distinguishing feature is that lipedema spares the feet entirely, stopping at the ankles, while lymphedema affects the feet. The fat in lipedema has a nodular texture rather than the smooth feel of regular body fat, and the affected areas bruise easily and can be painful to the touch. Some people with lipedema also notice unusual joint flexibility.
How to Reduce Swelling at Home
For mild, non-emergency swelling, a few strategies help move fluid out of your lower legs. Elevating your feet above heart level while resting lets gravity work in your favor. Moving your ankles in circles or flexing your feet periodically during long periods of sitting keeps the calf muscles pumping blood back upward.
Compression socks provide graduated pressure that supports your veins and prevents fluid from pooling. For mild swelling, 15 to 20 mmHg compression socks are available without a prescription and work well for daily use, travel, or long shifts on your feet. Moderate swelling typically calls for 20 to 30 mmHg, which your doctor may recommend. Severe or chronic conditions like lymphedema or advanced venous insufficiency require 30 to 40 mmHg or higher, which need a prescription and proper fitting.
Reducing sodium, staying physically active, and avoiding prolonged sitting or standing all help prevent fluid buildup from returning. If your swelling is new, persistent, affects only one side, or comes with pain, skin changes, or shortness of breath, those patterns point toward causes that need medical evaluation rather than home management.