Leg Swelling: Causes and When to Worry

Swollen legs: signs and symptoms

Leg swelling can be subtle or obvious. Common signs are:

• puffy ankles, feet or calves, often worse in the evening
• socks leaving deep marks, or shoes feeling tight
• skin that looks stretched or shiny
• pitting: pressing a finger into the skin for 5 to 10 seconds leaves a dent
• a heavy, tight or aching feeling in the legs
• reduced flexibility at the ankle
• weight gain from retained fluid

Pitting edema means fluid in the tissues and points to vein, heart, kidney, liver or medicine causes. Non-pitting swelling, which stays firm when pressed, is more typical of lymphedema, an underactive thyroid or lipedema.

One leg or both? The key question

Causes of leg swelling

Everyday causes

• Standing or sitting for long periods, including long flights and car trips. Leg muscles pump blood back to the heart; when they are still, fluid pools.
• Hot weather, which widens blood vessels.
• Being overweight, which raises pressure in the leg veins.
• Salt-heavy meals, which make the body hold water.
• Menstrual cycle and hormone changes.
• Pregnancy: mild ankle swelling is normal, especially in the third trimester.

Medicines

Calcium channel blockers (especially amlodipine and nifedipine), steroids, NSAIDs such as ibuprofen, estrogen, some diabetes medicines (pioglitazone), gabapentin and pregabalin can all cause swelling. Never stop a prescribed medicine without advice, but tell your doctor, as a switch often solves the problem.

Vein and lymph problems

• Chronic venous insufficiency: damaged valves in the leg veins let blood pool. Swelling is worse at night and better after sleep, with aching, varicose veins, brownish skin staining around the ankles and sometimes ulcers. This is the most common cause of ongoing swelling in older adults.
• Deep vein thrombosis (DVT): a clot in a deep vein, usually in one calf or thigh. The leg is swollen, tender, warm and sometimes red. Risk is higher after surgery, long travel, cancer, pregnancy, the contraceptive pill and inactivity.
• Lymphedema: blocked lymph drainage after cancer surgery, radiotherapy or infection, or from birth. Swelling is firm, often includes the toes, and does not go down overnight.

Heart, kidney and liver disease

These cause swelling in both legs because the body retains salt and water.

• Heart failure: a weak heart cannot keep up with returning blood. Swelling comes with breathlessness on exertion or lying flat, tiredness and weight gain.
• Kidney disease: damaged kidneys leak protein or fail to remove fluid. Puffiness around the eyes in the morning and foamy urine suggest nephrotic syndrome.
• Liver disease: cirrhosis lowers blood protein and raises pressure in abdominal veins, causing leg swelling and a swollen belly (ascites).
• Pulmonary hypertension: high pressure in the lung arteries strains the right side of the heart.

Infection and inflammation

• Cellulitis: a bacterial skin infection, usually in one leg, with redness, heat, pain and often fever.
• Arthritis and gout: swelling centered on a joint such as the knee or ankle.
• Ruptured Baker's cyst: fluid from behind the knee leaks into the calf, causing sudden calf pain and swelling that can mimic a clot.

Other causes

• Underactive thyroid: firm, non-pitting swelling with tiredness, weight gain and feeling cold.
• Lipedema: symmetrical fat buildup in both legs, mostly in women, that spares the feet.
• Malnutrition and very low protein levels.
• Injury: sprains, fractures and muscle tears.

Causes of extreme leg swelling

Very large, tense or rapidly worsening swelling usually comes from one of these:

• Severe heart failure, especially when combined with kidney problems
• Nephrotic syndrome or advanced kidney failure
• Advanced liver disease
• Extensive DVT that blocks the main thigh or pelvic veins. In rare cases the leg turns bluish and very painful (phlegmasia), which is an emergency
• Long-standing lymphedema, which can make the leg very large and the skin thick and warty
• Compartment syndrome after an injury, where pressure inside the muscle cuts off blood flow

Extreme swelling can make the skin weep clear fluid, blister or break down, which raises the risk of infection.

Leg swelling and shortness of breath

Swelling in both legs with breathlessness on walking is a classic pattern of heart failure. Other clues are needing more pillows to breathe at night, waking up breathless, a cough when lying down, tiredness and rapid weight gain. It needs a prompt medical review, and the same day if breathing is getting worse.

Swelling in one leg followed by sudden breathlessness or chest pain can mean a deep vein thrombosis that has traveled to the lungs (pulmonary embolism). Call 911 or your local emergency number.

Lung disease such as COPD and pulmonary hypertension can also cause both symptoms together.

Swollen legs with lumps

Lumps with leg swelling have several possible explanations:

• Varicose veins: soft, bulging, twisted veins that are worse on standing.
• Superficial thrombophlebitis: a hard, tender, red cord along a surface vein.
• Baker's cyst: a soft lump behind the knee.
• Lipedema: tender, nodular fat in both legs.
• Erythema nodosum: tender red lumps on the shins, linked to infections, sarcoidosis, inflammatory bowel disease and some medicines.
• Enlarged lymph nodes in the groin, which can block drainage.

Any lump that is growing, hard, fixed or painful should be examined.

Leg swelling and confusion

Swelling with new confusion is a warning sign. It can mean that kidneys or liver are failing to clear toxins, that sodium levels are dangerously low (sometimes from diuretics), that oxygen levels are low from heart failure, or that an infection such as cellulitis has spread into the blood (sepsis). Older adults may show confusion before other signs. Treat it as an emergency.

How doctors diagnose the cause

The doctor will ask when the swelling started, whether it affects one or both legs, whether it goes down overnight, and about breathing, urine, medicines, travel and recent surgery. They will examine the legs for pitting, warmth and skin changes, and listen to the heart and lungs.

Common tests include:

• Urine test for protein
• Blood tests: kidney and liver function, albumin, thyroid tests, blood count and sometimes BNP (a heart failure marker) or D-dimer (a clot screen)
• Duplex ultrasound of the leg veins to look for a clot or faulty valves
• Echocardiogram (heart ultrasound) and ECG if heart failure is suspected
• Lymphoscintigraphy in uncertain cases of lymphedema

Treatment for swollen legs

Treatment targets the cause: blood thinners for DVT, antibiotics for cellulitis, diuretics and heart medicines for heart failure, kidney or liver care, or stopping a medicine that causes swelling.

Home care for mild swelling

• Raise your legs above the level of your heart for 20 to 30 minutes, 3 or 4 times a day.
• Keep moving. Walk, and flex your ankles regularly on long trips.
• Compression stockings help vein-related swelling. Ask your doctor first if you have poor circulation, diabetes or numb feet, as tight stockings can harm legs with blocked arteries.
• Cut down on salt.
• Lose excess weight.
• Care for your skin: moisturize daily and treat cuts promptly, because swollen skin heals slowly and infects easily.

Water tablets (diuretics) are not a fix for swelling caused by veins, heat or standing, and they can cause dehydration and low sodium. Only take them when prescribed.

Frequently asked questions

What are the signs and symptoms of swollen legs?

Puffy ankles, feet or calves, tight shoes, sock marks, shiny or stretched skin, and a dent that stays after pressing the skin are the main signs. The legs may feel heavy, achy or stiff. Weight gain and swelling that is worse at the end of the day are common.

When is leg swelling an emergency?

Call 911 or your local emergency number if leg swelling comes with sudden shortness of breath, chest pain, coughing blood, confusion, or a leg that is cold, pale or extremely painful. Get same-day care for sudden swelling in one leg, or a red, hot leg with fever.

Why is only one of my legs swollen?

Swelling limited to one leg usually has a local cause: a blood clot, a skin infection, an injury, a ruptured Baker's cyst or blocked lymph drainage after surgery. Because a clot is possible, new swelling in one leg should be checked the same day, often with an ultrasound scan.

Does drinking more water help leg swelling?

Drinking enough water does not cause swelling and may help the kidneys clear salt. Cutting back on salt, moving more and raising your legs make a bigger difference. People with heart failure or advanced kidney disease may be told to limit fluids, so follow your doctor's advice.

Can leg swelling be a sign of heart problems?

Yes. Swelling in both legs, especially with breathlessness on exertion or lying flat, tiredness and fast weight gain, is a common sign of heart failure. Your doctor can check with a blood test called BNP, an ECG and an echocardiogram.

Why do my legs swell at night?

Gravity pulls fluid into the legs during the day, so swelling and pressure build by evening. This is typical of venous insufficiency, long periods of standing and some medicines. Swelling that is gone by morning is usually less concerning than swelling that persists after a night's sleep.