Written by Shane McCarthy, DO | Reviewed by Farzon A. Nahvi, MD
Updated on June 12, 2024
Key takeaways:
Leg swelling is a common issue that can be caused by many different medical conditions.
Sometimes, swollen legs are a sign of a life-threatening problem that needs urgent evaluation.
Blood clots, pregnancy, infections, injuries, medications, heart disease, kidney disease, and liver disease are all common causes of leg swelling.
Treatment of leg swelling is different for each person and depends on the underlying cause.
Toa55/iStock via Getty Images
After taking off your socks at the end of a long day, you may notice “sock lines.” These indentations, and the puffiness above them, are signs of swollen legs (edema). But where did it come from? And should you be concerned?
As it turns out, there are lots of different causes of swollen legs. Some are nothing to worry about. But others need urgent medical attention. We’ll help you figure out the difference.
Why do legs swell?
Legs — and any part of your body — can swell when fluids leak from inside blood vessels into surrounding body tissues. This is why this may happen:
Small amounts of fluid leak from blood vessels into nearby tissues all the time.
Normally, the lymphatic system cleans up these leaks, so tissues don’t swell.
If the lymphatic vessels can’t keep up with the leakage, swelling can build up.
This is particularly common in the legs because of the effects of gravity on tissue fluid.
Here are some of the reasons why this cause of leg swelling may be more likely:
Sitting still for long periods: Lower leg swelling is more likely if you have been sitting still for a long time. Moving your leg muscles helps to return blood to the heart.
Standing for long periods: You’re likely to get swollen legs if you’ve been standing for a long period of time, as your veins and lymphatics are having to work against gravity to mop up the fluid leak.
Hot weather: Leg swelling can be worse if it’s hot. That’s because blood vessels distend, and more fluid leaks out into the tissues.
Old injuries: Swelling is also more likely if you have old injuries that may have damaged blood vessels and lymphatic vessels. This damage may cause them to be unable to pump blood as well as before. That’s why you may notice that the ankle you broke years ago is always a little swollen.
Is some ankle swelling normal?
Swelling around the ankles and lower legs can be normal. After all, who hasn’t noticed sock lines around their legs every now and then at the end of a long day? For most of these “normal” causes of swollen legs, taking a walk, massaging the legs, or elevating them usually resolves the swelling.
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But what if the swelling doesn’t resolve with these strategies? And what if your legs are more swollen than what could be considered normal? It can help to think about the timeframe and whether one or both legs are affected when trying to figure out what might be causing your swollen legs.
What causes swelling in the legs (edema)?
Here are some possible causes of leg swelling that comes on over less than 72 hours.
One swollen leg
Two swollen legs
A blood clot that blocks blood flow in a large leg vein — also called deep vein thrombosis (DVT)
An injury like a broken leg or a pulled leg muscle
An infection in the skin, joint, or other tissue of the leg
Joint inflammation in a joint of the leg (like the knee), which can be caused by things like an injury or rheumatoid arthritis
Medication side effects from some blood pressure medications (like amlodipine or nifedipine), hormones, steroids, and even ibuprofen
Rapid worsening of a medical problem like heart failure, kidney disease, or liver disease
Untreated thyroid disease, like hypothyroidism
High-salt diet
Pregnancy
Always contact your healthcare professional when a lot of leg swelling happens really quickly. This could be a sign of a blood clot. And if your heart isn’t pumping like it should — or if your liver or kidneys aren’t filtering like they should — fluid overload occurs, and swollen legs is one symptom you may notice. These need urgent medical evaluation and treatment.
What causes chronic leg swelling?
Let’s say that your leg swelling didn’t come on all of a sudden. Instead, it has been developing gradually over a longer period of time (weeks to months). This is chronic leg swelling. Let’s review some typical causes of chronic leg swelling.
One swollen leg
Two swollen legs
Damaged veins or lymphatic vessels can happen with an old leg injury. A blood clot can also damage vessels, leading to leg swelling known as postthrombotic syndrome.
A mass or tumor compressing vessels of one leg can slow down fluid flow through veins and lymphatic vessels as it grows. And you may see a swollen leg worsen over time.
Slow worsening of medical problems like heart failure, liver disease, kidney disease, or thyroid disease
Damaged veins or lymphatic vessels
Medication side effects
Pregnancy
Obesity
A mass or tumor pushing on the vessels of both legs, slowing down fluid flow
Idiopathic (unknown)
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How do you diagnose the cause of swollen legs?
With so many causes of swollen legs, it can be hard to know what’s going on for you — and importantly, how to treat it.
But there are some ways your healthcare professional can help narrow down the cause. Often, they’ll start by asking you questions about your health and symptoms. Common questions may include:
Did you have an injury or a recent surgery?
Have you not moved for a long period of time? For example, a long flight or car journey, or recent illness or surgery.
Is your swollen leg painful?
Are you taking any new medications?
They may also ask questions about your risk for blood clots, like if you take birth control pills or other hormones, have a cancer diagnosis, or a family history of blood clots.
After you have had a physical exam, your healthcare professional may order some of the following tests:
An ultrasound of the leg — a venous Doppler — to look for blood clots.
Blood tests to check the kidneys, liver, and thyroid.
An echocardiogram — an ultrasound scan of the heart — to look for heart failure. This is usually ordered along with an electrocardiogram (EKG) and a chest X-ray.
An MRI, CT, or another type of imaging scan to look for tumors pressing against the veins.
Consider taking photos of your swollen legs to show your healthcare professional, in case your leg swelling isn’t noticeable during the visit. You can also mark the top of the swelling with a pen, noting the date and time. This lets you see how fast the swelling is increasing up your leg.
How do you treat swollen legs?
There are different ways to treat swollen legs. But which one is right for you depends on the cause.
Medications
Here are some medications your healthcare professional might prescribe for leg swelling, along with the problems that they treat:
Anticoagulants (blood thinners) — like Coumadin (warfarin), heparin, and Eliquis — are used to treat blood clots.
Antibiotics — like cephalexin — are used to treat cellulitis or skin infections.
Diuretics — also called “water pills” — are a class of medications that get rid of excess fluid in the body so you can urinate it out. They’re used to treat swelling from various causes — most often heart failure. Examples include furosemide, hydrochlorothiazide, and spironolactone.
Home remedies
Sometimes, a medication is all you need to treat swollen legs. But if your leg swelling is due to sluggish veins and lymphatics, your healthcare professional may recommend the following:
Elevate your legs: Elevate your legs above the level of your heart. This allows gravity to help drain excess fluid from your legs back towards your heart.
Exercise: Exercise keeps fluid moving through your lymphatics and veins, preventing it from pooling in your legs.
Massage: This helps move lymphatic fluid along, removing it from your legs.
Compression socks: Compression socks or stockings can help push fluids out of your legs and back into the lymphatics. But you’ll need to check with your care team that it’s safe for you to wear these. People with certain medical problems like peripheral artery disease and neuropathy shouldn’t wear compression socks.
Opt for a low-salt diet: Salt makes your body retain fluid, so limiting salt in your diet can help improve swelling.
Try natural diuretics: Parsley, dandelion tea, and hibiscus tea are all natural diuretics. Research has shown that they can help the body eliminate excess water.
Maintain a comfortable body weight: Being overweight increases the risk of leg swelling, so losing excess pounds, if achievable, may help improve or prevent leg swelling.
Epsom salts: There’s not a lot of research to support this, but lots of people claim that Epsom salt baths help reduce swelling.
Is leg swelling dangerous?
Here are some telltale signs that your swollen legs may be a sign of something serious. If you have any of these symptoms, you should seek medical attention right away:
The leg swelling comes on rapidly, in less than 72 hours. This is concerning for a blood clot in the leg, also called a deep vein thrombosis (DVT). Untreated, a DVT can lead to a pulmonary embolism. This is a more life-threatening complication where a blood clot breaks off and goes to the lungs.
The swollen leg is red, warm to touch, painful, with skin breakdown, or a fever. These can be signs of an infected leg or a DVT.
The leg swelling has come on rapidly in both legs. This suggests a body system isn’t working well — most commonly, the heart, kidneys, thyroid, or liver.
There’s a large amount of swelling in one or both legs. This could be a sign that the veins or lymphatics are blocked by a blood clot or a tumor.
The swollen leg is associated with other symptoms. If you also have chest pain, heart palpitations, dizziness, weakness, confusion, or shortness of breath — you need to get checked out by your healthcare professional fast. It could be a sign of a serious and life-threatening problem affecting one of your major organs.
The swollen leg is extremely painful, pale, numb, or weak. This could be a sign of compartment syndrome. This is an emergency where swelling cuts off circulation to the leg, and it needs treating fast to save the leg.
Frequently asked questions
How do you know if leg swelling is heart-related?
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When leg swelling is caused by a heart problem, it usually goes along with difficulty breathing. That’s because the same things that cause a buildup of fluid in the legs can cause a fluid buildup in the lungs. You may notice you have trouble breathing that is worse when you lie down flat and better when you sit upright. But that’s not always the case.
Will drinking water reduce leg swelling?
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What foods should you avoid when you have swollen legs?
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The bottom line
Mild leg swelling of the feet and ankles every once in a while, or at the end of a long or hot day, is normal. This is especially true if you’ve been on your feet a lot or sitting down at a desk for long periods of time. Leg swelling can also be a side effect of medications.
A sudden change in the size of one or both legs can be a sign of a more serious medical problem. You should seek urgent medical attention if your leg swelling is new. For longer-term leg swelling, there may not be an easy fix. But your medical team can rule out a serious underlying cause and recommend changes to your everyday life to make your leg swelling more manageable.
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Why trust our experts?
Written by:
Shane McCarthy, DO
Shane McCarthy, DO, practices full-spectrum family medicine and is board certified through the American Board of Family Medicine. She has over 20 years of experience.
Edited by:
Sophie Vergnaud, MD
Sophie Vergnaud, MD, is an experienced and dedicated pulmonologist and hospitalist who spent a decade practicing and teaching clinical medicine at academic hospitals throughout London.
Reviewed by:
Farzon A. Nahvi, MD
Dr. Nahvi is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works clinically at Concord Hospital in Concord, New Hampshire, and is a clinical assistant professor of emergency medicine at the Geisel School of Medicine at Dartmouth.
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References
Clare, B., et al. (2009). The diuretic effect in human subjects of an extract of Taraxacum officinale folium over a single day. Journal of Alternative and Complementary Medicine.
Ely, J. W., et al. (2006). Approach to leg edema of unclear etiology. Journal of the American Board of Family Medicine.
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