Swollen feet happen when excess fluid builds up in the tissues of your lower extremities. This is called peripheral edema, and it ranges from a harmless response to gravity and salt intake all the way to a signal of heart, kidney, or liver problems. The cause matters enormously, so understanding what type of swelling you have, whether it affects one foot or both, and what other symptoms come with it can point you in the right direction.
Why Fluid Pools in Your Feet
Your blood vessels constantly exchange fluid with the surrounding tissue. Tiny capillaries push fluid out under pressure, and your body reabsorbs most of it through a combination of protein balance in the blood and lymphatic drainage. When any part of that system gets disrupted, fluid accumulates in the spaces between your cells instead of cycling back into circulation.
Gravity plays a major role. Blood has to travel a long way from your feet back up to your heart, and the veins in your legs rely on one-way valves and muscle contractions to push it upward. When you sit or stand for hours without much movement, fluid naturally settles downward. That’s why your feet may look puffy after a long flight or a day at a desk but return to normal after you elevate them overnight.
Common Causes of Swollen Feet
Chronic Venous Insufficiency
This is one of the most frequent culprits. Chronic venous disease affects over 25 million adults in the United States alone. It happens when the valves inside your leg veins weaken or fail, allowing blood to pool in the lower legs instead of flowing efficiently back to the heart. You’ll typically notice soft, pitting swelling (meaning a finger pressed into the skin leaves a temporary dent) along with a feeling of heaviness, aching, or itching. Over time, the skin around the inner ankle can take on a brownish or reddish discoloration from iron deposits leaking out of stagnant blood.
Heart, Kidney, or Liver Problems
When the heart can’t pump blood effectively, pressure builds in the veins and pushes fluid into the tissues. Heart failure is a classic cause of swelling in both feet and ankles, often worse at the end of the day. Kidney disease causes swelling through a different route: the kidneys stop filtering sodium and water efficiently, so your body retains more fluid overall. Liver disease, particularly cirrhosis, reduces your blood’s ability to hold onto fluid (because the liver produces less of the proteins that keep fluid inside your vessels), so it leaks out into surrounding tissue.
All three of these conditions tend to cause swelling in both feet equally. If you notice swelling that worsens over weeks, comes with shortness of breath, or doesn’t improve with elevation and rest, those are signs something systemic is going on.
Medications
Several common drug classes cause foot swelling as a side effect. Calcium channel blockers, a widely prescribed group of blood pressure medications, are among the most notorious. The swelling rate with these drugs ranges from 1 to 15% depending on the specific medication and dose, with the dihydropyridine type (like amlodipine and nifedipine) more likely to cause it than others in the same class. Anti-inflammatory painkillers, steroids, diabetes medications, and some hormone therapies can also trigger fluid retention. If your swelling started shortly after beginning a new medication, that connection is worth raising with your prescriber.
Pregnancy
Mild foot swelling is normal during pregnancy, especially in the third trimester, because your body carries significantly more blood volume and your growing uterus puts pressure on the veins returning blood from your legs. What isn’t normal is sudden swelling in your face, hands, or around your eyes, particularly if it comes with high blood pressure or severe headaches. That pattern can signal preeclampsia, a serious pregnancy complication that needs prompt medical attention.
One Foot vs. Both Feet
Whether the swelling is in one leg or both is one of the most important clues to its cause. Swelling in both feet usually points to a body-wide issue: fluid retention from too much sodium, a medication side effect, or an organ-related condition like heart or kidney disease. It’s often gradual and symmetrical.
Swelling in just one foot or leg raises different concerns. A blood clot in a deep vein, known as deep vein thrombosis, is the one that needs urgent attention. The classic signs include swelling in one leg along with pain or cramping (often starting in the calf), skin that feels warm to the touch, and a color change toward red or purple. A DVT becomes dangerous if the clot breaks loose and travels to the lungs, causing a pulmonary embolism. Warning signs of that include sudden shortness of breath, chest pain that worsens with deep breathing, a rapid pulse, dizziness, or coughing up blood. That combination is a medical emergency.
Other causes of one-sided swelling include an injury, an infection, or lymphedema, which occurs when the lymphatic drainage system is damaged or blocked.
Pitting vs. Non-Pitting Swelling
If you press your thumb firmly into the swollen area for a few seconds and it leaves a visible dent, that’s pitting edema. Clinicians grade it on a scale from 1 to 4 based on how deep the pit 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 sinks about 8 millimeters and takes two to three minutes to fill back in. Higher grades generally suggest more significant fluid overload.
Non-pitting swelling, where the skin feels firm or doughy and doesn’t indent easily, is characteristic of lymphedema. In the early stages lymphedema can still pit, which makes it tricky to distinguish, but over time the tissue becomes thickened and fibrotic. One useful sign: if you can’t pinch the skin on the top of the second toe into a fold, that strongly suggests lymphedema. Unlike a blood clot, lymphedema is typically painless when you press on it.
Reducing Swelling at Home
For mild, everyday swelling, a few strategies make a real difference. Elevating your feet above heart level for 20 to 30 minutes helps gravity work in your favor, draining fluid back toward your core. Moving regularly, even just walking or flexing your calves, activates the muscle pump in your legs that pushes blood upward through your veins.
Sodium is a major driver of fluid retention. The American Heart Association recommends most adults stay under 2,000 mg of sodium per day, and for people with heart failure or persistent swelling, guidelines from multiple cardiology societies converge on a limit of 2,000 mg or less. For context, a single fast-food meal can easily contain 1,500 mg or more, so cutting back on processed and restaurant foods tends to have the biggest impact.
Compression stockings provide external support for your veins and help prevent fluid from pooling. For venous insufficiency, the standard therapeutic range is 20 to 30 mmHg of pressure. More severe cases, including lymphedema or post-clot syndrome, may require 30 to 40 mmHg stockings, which typically need a prescription. Compression works best when you put the stockings on first thing in the morning before swelling has a chance to develop.
When Swelling Points to Something Serious
Most foot swelling is benign and responds to simple measures. But certain patterns deserve prompt attention. Swelling in one leg with pain, warmth, and color change could be a blood clot. Swelling that comes on rapidly alongside shortness of breath may indicate a heart or lung problem. Swelling during pregnancy with facial puffiness, headaches, or vision changes can signal preeclampsia. And swelling that steadily worsens over weeks without an obvious cause, like prolonged sitting or a new medication, warrants investigation into how your heart, kidneys, and liver are functioning.
Paying attention to the pattern gives you the clearest picture: is it one leg or both, does it pit or not, did it start suddenly or gradually, and what else changed around the same time? Those details are exactly what will help determine the cause and the right next step.