>Have you noticed your feet, ankles or lower legs looking puffier than usual? This swelling is called edema, and it happens when fluid builds up in your body’s tissues. Sometimes it’s just your body reacting to a long day of standing. Other times, it could be a sign of something more serious.

• Gravity: Standing or sitting too long can cause fluid to pool in your legs.
• Injury: A sprain or bump can lead to swelling in the affected area.
• Too much salt: Eating salty foods can make your body hold onto water.
• Pregnancy: Hormonal changes and pressure from the baby can cause feet and ankles to swell.
• Obesity: Extra weight puts pressure on your veins, affecting blood flow.
• Varicose veins: Twisted veins can slow blood flow and lead to poor circulation.
• Chronic conditions: Heart failure, kidney disease and liver disease can cause fluid buildup.
• Lymph nodes: Problems with the drainage of lymph node fluid can cause swelling, which is known as lymphedema.

Medications that may cause swelling:

• Blood pressure medications, especially calcium channel blockers
• Hormones like estrogen or testosterone
• Steroids
• Certain antidepressants

Always talk to your doctor before stopping any medication.

“Sometimes lower extremity swelling is caused by more than one factor,” says Gabriel A. Wallace, MD, a vascular surgeon and director of Vascular Surgery for Northwestern Medicine Bluhm Cardiovascular Institute at Palos Hospital. “A comprehensive assessment may be necessary to identify and address all contributing causes.”

When Swelling Could Be Serious

Most swelling goes away with rest. But sometimes, it’s a warning sign. Watch for:

• Sudden swelling in one leg
• Swelling in both legs
• Red, warm or painful swollen areas
• Trouble breathing or chest pain
• Rapid heart rate
• Skin changes like wounds or fluid leakage

Swelling in one leg

Sudden swelling in one leg could mean a blood clot, known as deep vein thrombosis (DVT). If the clot travels to the lungs, it can cause a pulmonary embolism (PE), which is a life-threatening condition and requires immediate medical attention.

Dr. Wallace adds that chronic swelling in the left leg may also be caused by May-Thurner syndrome, a condition where the iliac vein in the pelvis is compressed. Tests like ultrasound, CT scans and sometimes invasive venography can help diagnose it, he says.

“Treating iliac vein compression may improve left leg swelling related to May-Thurner syndrome but should only be done by professionals with experience in this area to ensure that it is done for the correct reason with a good chance of symptom improvement,” says Dr. Wallace. “Benign compression of the iliac vein is commonly detected incidentally on CT scans performed for other reasons.”

If you are interested in treatment for iliac vein compression, specialists are available to help determine if it’s the right option for you.

Swelling in both legs

If you experience swelling in both legs — especially when accompanied by fatigue and shortness of breath — this could be a sign of heart failure. This needs prompt medical care.

How the Cause of Swelling Is Determined

To find the cause, your care team may use:

• Blood tests to check heart, kidney and liver function
• Ultrasound to look for blood clots
• Urine tests to check for protein loss
• Imaging to assess blood flow and vein health

A special ultrasound test called venous reflux ultrasound, or venous insufficiency study, can show if your veins are working properly.

“When this test is normal, any swelling that is present is unlikely to be related to a vascular issue,” says Dr. Wallace. “But even with abnormal results, swelling may have more than one cause. This highlights the critical importance of evaluation at an accredited vein center.”

How Chronic Conditions Affect Swelling

Conditions like diabetes, kidney disease and venous insufficiency can affect how your body moves fluids. When your organs or veins work less efficiently, fluid can collect in your legs, feet and ankles.

With venous insufficiency, swelling can happen because your veins return blood to the heart and have valves to keep it from flowing backward. If these valves work less well (are “insufficient”), pressure can build up. This can cause swelling, discomfort and even skin wounds that can ooze fluid.

Lifestyle Habits That Can Make Swelling Worse

Your daily habits matter. Swelling can get worse if you:

• Sit or stand too long
• Eat salty foods
• Don’t move enough

Can Swelling Be Prevented?

Yes — in many cases, it can. Try these tips to help prevent or reduce swelling in your legs, feet or ankles:

• Move often and take short walks, especially during long travel.
• Keep your weight in a healthy range. “Maintaining a healthy weight is the number one lifestyle change that can help with lower extremity swelling,” says Dr. Wallace.
• Eat less salty foods.
• Stay hydrated by drinking plenty of water.
• Raise your legs above heart level when resting.
• Avoid sitting or standing for long periods.
• Avoid tight shoes.
• Wear compression stockings.

When compression therapy helps

Compression stockings are often recommended for:

• Varicose veins
• Chronic venous insufficiency
• Swelling from sitting or standing too long

“Compression stockings and leg elevation can make a huge improvement in leg swelling, whether the swelling is caused by vein or other problems,” says Dr. Wallace. “It is important to elevate the legs at night or at least have them flat with your body. Put on the compression stockings in the morning when the feet and legs are less swollen than at the end of the day.”

For deeper vein issues, compression is usually the best option. Other treatments like endovenous ablation may be used for vein problems closer to the skin. Your care team can help you decide the right treatment plan for you.