Swollen Feet (Foot Swelling)

Why feet swell

Gravity pulls fluid down toward the feet. Normally, calf muscles squeeze veins to push blood back up, one-way valves stop it falling back, and the lymphatic system drains extra fluid. Feet swell when:

• veins cannot return blood well (weak valves, a clot, inactivity)
• the heart cannot pump fluid forward efficiently
• the kidneys hold on to salt and water, or lose protein
• the liver cannot make enough albumin, a protein that keeps fluid in the blood
• the lymph system is damaged
• tissues are inflamed by injury, infection or arthritis

Swelling in both feet

Everyday causes

• long periods of standing, sitting or flying
• hot weather
• high-salt meals
• being overweight
• premenstrual fluid retention
• pregnancy: mild swelling is common, especially in the third trimester

Medicines

Calcium-channel blockers such as amlodipine are a very common cause. Others include steroids, NSAIDs, estrogen and hormonal contraceptives, some diabetes medicines (pioglitazone), and gabapentin and pregabalin.

Vein problems

Venous insufficiency is weak vein valves that let blood pool in the legs. Swelling is worse at the end of the day and improves overnight. Over time, the skin near the ankles becomes brown, itchy and hard, and ulcers can form. Varicose veins often accompany it.

Heart, kidney and liver disease

Swelling in one foot

Swelling in one foot needs a different line of thought:

• Injury: a sprain, fracture or tendon injury, usually with pain and bruising.
• Deep vein thrombosis: a clot in a deep leg vein. Swelling of the calf and ankle, pain, warmth and redness. Risk rises after surgery, long travel, cancer, pregnancy, hormone use and immobility.
• Cellulitis: a skin infection with spreading redness, warmth, pain and often fever. Athlete's foot cracks are a common entry point.
• Gout: sudden, intensely painful, red, swollen joint, often the big toe.
• Baker's cyst rupture: fluid from the back of the knee tracking down to the calf and ankle.
• Lymphedema: after cancer surgery, radiation or infection. Swelling includes the toes and feels firm.
• Charcot foot: in people with diabetes and nerve damage, a warm, red, swollen foot with little pain, from bone and joint breakdown.
• Post-thrombotic syndrome after a past DVT.

How to tell what kind of swelling it is

• Pitting: press a thumb on the swollen area for 5 seconds. A dent that stays is pitting edema, typical of fluid from veins, heart, kidney or liver causes.
• Non-pitting: firm swelling that does not dent suggests lymphedema or thyroid disease.
• Overnight change: swelling that disappears overnight is usually vein or gravity-related. Persistent swelling suggests a systemic cause.

How doctors find the cause

A doctor will ask whether one or both feet are affected, how quickly it started, about breathlessness, urine changes, medicines, travel, surgery, pregnancy and diet. They will check the heart, lungs, abdomen, legs and skin, and press for pitting.

Common tests:

• urine test for protein
• blood tests: kidney and liver function, albumin, blood count, thyroid, BNP for heart failure
• D-dimer and duplex ultrasound of the leg veins for suspected DVT
• echocardiogram for heart function
• venous ultrasound for vein valve problems
• X-ray after injury

How to reduce swelling in feet

• Elevate your feet above the level of your heart for 30 minutes, 3 to 4 times a day.
• Move: walk regularly and flex your ankles when sitting for long periods, especially on flights.
• Compression stockings: graduated stockings help vein-related swelling. Check with a doctor first if you have poor circulation or diabetes.
• Cut down on salt.
• Keep cool in hot weather.
• Wear comfortable shoes that do not dig in.
• Review medicines with your doctor. Do not stop a prescribed medicine yourself.
• Lose weight if overweight.

Water pills (diuretics) treat swelling caused by heart, kidney or liver disease but are not used for simple gravity-related swelling, where they can cause dehydration and electrolyte problems.

Swollen feet in pregnancy

Mild swelling is normal, especially later in pregnancy and in hot weather. Rest on your left side, elevate your feet, avoid standing for long, and wear supportive stockings. Sudden swelling of the face and hands, or swelling with headache or vision changes, can mean preeclampsia. One-sided swelling with calf pain can be a clot. See swelling in pregnancy.

Frequently asked questions

What causes swollen feet?

Common causes are standing or sitting for long periods, hot weather, pregnancy, being overweight, a salty diet and medicines like amlodipine. Vein problems are frequent in older adults. Heart, kidney or liver disease, blood clots and infections are less common but more serious causes.

When should I worry about swollen feet?

Get urgent care if swelling comes with shortness of breath, chest pain, calf pain, redness and warmth, fever, or if one foot suddenly swells. See your doctor if swelling does not go down overnight, keeps getting worse, or comes with weight gain or changes in urine.

Why is only one foot swollen?

One-sided swelling usually has a local cause: an injury, a blood clot, a skin infection, gout, a burst Baker's cyst or lymphedema. A blood clot is the most important to rule out, especially with calf pain, warmth or recent travel or surgery.

How do I reduce swelling in my feet quickly?

Lie down and raise your feet above heart level, move your ankles in circles, walk around, avoid salty food, and wear compression stockings if suitable. A cool foot soak can help. Swelling that does not respond or keeps returning should be checked by a doctor.

Can heart problems cause swollen feet?

Yes. In heart failure the heart cannot pump efficiently, so fluid backs up into the legs and lungs. Swelling usually affects both feet and ankles and comes with breathlessness, fatigue and rapid weight gain. These symptoms need medical review.