Why Are My Feet and Ankles Swollen? Causes and When to Worry

Swollen feet and ankles are very common, especially at the end of a long day, after a flight, or in hot weather. Most of the time the cause is simple gravity, and the swelling goes down overnight.

Sometimes, though, swelling is a sign that the heart, kidneys, liver, or veins need attention, or that a blood clot has formed. This guide explains the common causes, how to read the pattern of your swelling, and the warning signs that mean you should get help quickly. It can help you decide what to do next, but it cannot diagnose the cause.

Why are my feet and ankles swollen?

Swelling in the feet and ankles usually happens because fluid collects in the tissues of the lower legs, a condition called edema. Gravity pulls fluid downward, so the feet and ankles are where it shows up first.

According to MedlinePlus, painless swelling of both feet and ankles is common, particularly in older adults. It is often caused by being on your feet or sitting for a long time, but it can also reflect a problem elsewhere in the body.

Swelling is one of many everyday symptoms covered in our physical health guide, and as with most of them, the details (one leg or both, sudden or gradual, painful or not) tell you the most.

What are the most common causes of swollen feet?

The most common causes are prolonged standing or sitting, heat, pregnancy, extra body weight, injury, and certain medicines. Ongoing swelling can also come from vein, heart, kidney, or liver conditions.

Cause	Typical pattern	Other clues
Long periods of standing or sitting, including travel	Both feet, worse late in the day, better by morning	Sock marks, mild tightness
Hot weather	Both feet and sometimes hands	Eases as the weather cools
Pregnancy	Both feet, often in the later months	Sudden swelling of face or hands needs a prompt call
Medicines	Both ankles, starting after a new medicine	Common with some blood pressure drugs, steroids, NSAIDs, and hormones
Injury such as a sprain	One ankle, quickly after a twist or fall	Pain, bruising, trouble bearing weight
Chronic venous insufficiency	Both legs, gradual, worse with standing	Varicose veins, aching, brownish skin near the ankles
Deep vein thrombosis (blood clot)	Usually one leg, comes on over hours to days	Pain, warmth, redness, tenderness in the calf
Heart, kidney, or liver disease	Both legs, ongoing	Breathlessness, fatigue, foamy urine, or yellow skin

Does it matter if one foot or both feet are swollen?

Yes. Swelling in both feet usually points to something affecting the whole body or both legs, such as heat, standing, medicines, or a heart, kidney, or liver problem. Swelling in just one leg is more likely to be local, such as an injury, an infection, or a blood clot.

Feature	Both feet	One foot or leg
Common harmless causes	Heat, long days on your feet, travel, pregnancy	A recent sprain or bump
Causes that need a doctor	Medicines, vein problems, heart, kidney, or liver disease	Blood clot, skin infection (cellulitis), joint problem
Most urgent concern	Swelling with shortness of breath	Swelling with calf pain, warmth, and redness

If one ankle swelled up right after a twist or fall, the question is usually whether a bone is involved, which our article on telling a sprain from a fracture walks through.

When are swollen feet a sign of something serious?

Swollen feet can be a sign of a serious condition when the swelling is new and in one leg, comes with pain or skin changes, or comes with symptoms elsewhere in the body.

Blood clot

Deep vein thrombosis (DVT) is a blood clot in a deep vein, usually in the calf or thigh. According to NHLBI, it often causes swelling, pain, warmth, and redness in one leg, though some clots cause few symptoms. A clot can break off and travel to the lungs, called a pulmonary embolism, which is an emergency. Risk is higher after surgery, long trips, being immobile, pregnancy, hormonal birth control, cancer, or a previous clot.

Heart failure

Heart failure means the heart is not pumping as well as it should, so fluid backs up. According to NHLBI, swelling in the feet, ankles, and legs is a common sign, often alongside shortness of breath, tiredness, and needing to sleep propped up on pillows. Rapid weight gain of a few pounds over a few days can mean fluid is building up.

Kidney and liver disease

When the kidneys cannot remove enough fluid and salt, swelling can appear in the legs and around the eyes. Repeatedly foamy urine can be a clue, as explained in our guide to what urine color and foam mean. Liver disease can cause swelling in the legs and abdomen, sometimes with yellowing of the skin or eyes.

Infection

Cellulitis is a bacterial skin infection that makes the skin red, swollen, warm, and painful, usually on one leg. It can spread quickly, especially with fever, and needs prompt treatment, often with antibiotics.

How can you tell if swelling is pitting edema?

Pitting edema means a dent stays in the skin after you press on it. Press a thumb firmly into the swollen area for about five seconds and let go; if a dimple remains for a moment, the swelling is pitting.

Pitting is common with fluid buildup from standing, vein problems, heart failure, and kidney or liver disease. It does not tell you the cause on its own, but it is useful information to share with your doctor, along with how far up the leg it goes and how long the dent lasts.

What if the swelling does not pit?

Swelling that stays firm when pressed is called non-pitting edema. One cause is lymphedema, a buildup of lymph fluid that happens when the lymphatic system, the network of vessels that drains fluid from tissues, is damaged or blocked. It can follow cancer surgery, radiation therapy, or infection, and it often makes the leg feel heavy and the skin gradually thicken.

Lymphedema usually needs specialist care, such as compression garments and a type of gentle massage taught by a trained therapist, so mention it to your doctor if your swelling feels firm or has been building over months.

What helps swollen feet and ankles at home?

For mild swelling without warning signs, simple steps often help. These work best for swelling caused by standing, sitting, heat, or travel, and they do not replace treatment of an underlying condition.

• Raise your legs. Lie down with your feet above the level of your heart for about 30 minutes a few times a day.
• Keep moving. Walking and simple ankle circles or calf raises help your calf muscles pump fluid back toward the heart. If you work at a desk, short breaks every hour help, and moving more during long sitting days covers practical ways to do that.
• Cut back on sodium. Salt makes the body hold on to water. The Dietary Guidelines for Americans advise less than 2,300 mg of sodium a day.
• Try compression socks. Graduated compression stockings can reduce swelling from vein problems, but ask your doctor first if you have diabetes, poor circulation, or a skin condition.
• Move during travel. On long flights or drives, stand up, walk, and flex your ankles regularly, and drink enough fluids.
• Review your medicines. If swelling started after a new medicine, talk to your doctor or pharmacist, but do not stop a prescribed medicine on your own.

What causes swollen feet during pregnancy?

Some swelling in the feet and ankles is normal in pregnancy, especially in the third trimester, because the body holds more fluid and the growing uterus presses on veins in the pelvis. It is often worse at the end of the day and in hot weather.

According to ACOG and MedlinePlus, sudden swelling of the face or hands, or swelling with a severe headache, vision changes, or pain in the upper abdomen, can be a sign of preeclampsia, a dangerous rise in blood pressure. Call your obstetric provider right away if you notice these signs, during pregnancy or in the weeks after giving birth.

When should you see a doctor or call 911?

Call 911 or go to the emergency room if leg swelling comes with chest pain, shortness of breath, coughing up blood, or fainting, which could mean a blood clot has reached the lungs or a heart problem. Also seek emergency care for sudden, painful swelling in one leg with warmth and redness.

See a doctor the same day, or go to urgent care, if you have:

• Swelling in one leg that is new, especially with calf pain or tenderness
• Red, hot, or painful swollen skin, particularly with fever
• Swelling after an injury where you cannot put weight on the foot
• Swelling in pregnancy with headache, vision changes, or swelling of the face or hands
• Swelling with a known heart, kidney, or liver condition that is getting worse, or rapid weight gain

Talk to your primary care provider if swelling does not go down overnight, keeps coming back, is getting worse, or appeared after starting a new medicine. They may check your blood pressure, heart, urine, and blood tests, and sometimes order an ultrasound of the leg veins to look for a clot.