What Causes Leg Swelling?

Swelling is a collection of fluid inside your body’s tissues.

The legs can be a common area of swelling because gravity pulls the liquid down to the lowest point. There are several reasons your leg may be swelling, such as a problem with the kidneys, circulation, or lymph system.

This article goes over what leg swelling is and multiple things that can cause this condition.

It also talks about how your medical provider can diagnose what is going on and what treatments are available. Finally, learn how to prevent leg swelling and when it’s time to see a provider.

What Is Leg Swelling?

Leg swelling is when fluid collects in your legs. It can also be called peripheral edema.

Swelling may make your legs feel heavy and your skin tight. Some swelling can be severe, leaving a dent when you press on it (this is called “pitting edema”). 

Causes

Read on to learn more about the causes of leg swelling. 

Varicose veins

Varicose veins are enlarged, twisted, blue veins that you can see under the skin.

They are most common in the legs and are caused by the valves in the veins not working properly and blood collecting in the vein.

Typically varicose veins are harmless; however, they could lead to complications such as swelling, blood clots, pain, and skin changes. 

Joint problems

Joint problems such as gout, osteoarthritis, rheumatoid arthritis, and knee bursitis can lead to swelling in the tissues of the legs. 

Chronic venous insufficiency

The normal function of veins is to continue blood flow back to your heart.

However, when the vein walls and valves become damaged or weakened, the blood can begin to pool in the veins, especially while standing.

This condition is called chronic venous insufficiency and is a long-term condition.

Aging, being obese, pregnancy, and standing for long periods are risk factors for chronic venous insufficiency.  

Cellulitis

Cellulitis is a skin infection caused by bacteria.

The legs are common locations of this type of infection. Symptoms include redness, pain, and swelling. If left untreated, cellulitis can spread and cause further complications. 

Heart problems

Heart failure is a serious condition when the heart cannot pump blood around your body adequately.

Coronary artery disease, diabetes, high blood pressure, and obesity increase your risk for heart failure. 

Symptoms of heart failure include:

• Fatigue
• Shortness of breath with activity
• Trouble breathing while lying flat
• Swelling in your legs and feet
• Weight gain

Kidney problems

Your kidneys filter your blood and remove toxins and unneeded material. Kidney failure is when your kidneys stop working correctly, and those toxins build up.

It also causes a build-up of extra fluids. Diabetes, high blood pressure, and autoimmune diseases are some causes of kidney failure. 

Symptoms can include:

• Feet and ankle swelling
• Itchy skin
• Nausea
• Urinating less than normal

Lymphedema

Your lymph system carries fluids around your body and helps fight infections.

Lymphedema is when a build-up of fluids causes swelling because of a block or damage to the lymph system. Cancer, surgery, or radiation can cause it. 

Symptoms of the affected area can include:

• Swelling
• Tight skin
• Heavy feeling
• Thick or leathery skin

Blood clot

Blood clots are when the blood forms into a solid clump inside a blood vessel.

Clots can partially block or completely block the blood vessel and sometimes become dislodged and travel to other areas of the body.

Long-term bed rest, sitting for long periods while traveling, pregnancy, and birth control medications put you at risk for blood clots. 

Symptoms of a blood clot include:

• Unilateral swelling (or swelling that only occurs on one side of the body) 
• Redness 
• Pain
• Warm skin

Infection

Any time a wound gets infected, there will be some degree of swelling. Leg wounds are common, especially in older adults who have fragile skin.

While an injury heals, it needs to be kept clean and given the proper environment for healing. 

In addition, certain conditions such as diabetes, obesity, smoking, and decreased blood flow can increase your risk for infection and slow wound healing. 

Injury

Injury to the muscles or joints in your leg can cause your leg to swell.

To reduce swelling, try to rest the joint as much as possible.

Ice the injury for 20 minutes every four hours for the first 48 hours after the injury. 

Use a medical-grade compression wrap to wrap the injury firmly (but not too tightly). While resting, elevate the injury above your heart to encourage the fluid to flow back to the heart.

These steps should help reduce swelling in your leg. 

Pregnancy

During pregnancy, the weight of the uterus puts significant pressure on the blood vessels and lymph nodes in the legs and pelvis.

Sometimes this extra pressure makes it difficult for the fluid to travel back up to the heart.

As a result, it’s common for the ankles and feet to swell during pregnancy. 

When you rest, try and elevate your feet above your heart and cut down on salt in your diet.

These can help decrease the amount of swelling in your feet. 

Certain medications

Certain medications may cause your legs to swell. 

These include:

• Calcium channel blockers that treat blood pressure
• Estrogen used in birth control pills
• MAO inhibitors and tricyclics used as antidepressants
• Steroids

Never stop a medication without first speaking with the medical provider who ordered it for you.

Some medicines may need to be tapered in dosage as you transition off of them. 

Diagnosis

Your medical clinician will first complete a physical exam.

They will also want to review your medical history and current medications and vitamins. 

Blood work

Lab work can check the functioning of your heart, kidneys, and liver.

It can also indicate the presence of infection or a blood clot. 

Urine tests 

Urine tests will help look at kidney functions and check for protein spillage in the urine. 

Imaging

Ultrasound, magnetic resonance imaging (MRI), and computed tomography (CT) scans may help diagnose what is going on.

For example, these scans can see if tissue is damaged or if there is a blockage. 

Treatment

Treatment will depend on the underlying cause of the swelling. Your medical provider may order wound care, antibiotics, or medication to treat the condition causing you to swell. 

Sometimes a change in diet or weight loss and regular exercise can be helpful for these conditions. 

Some cases of leg swelling are temporary, while others may be more long-lasting.

It is important to follow your medical provider’s plan of care to reduce swelling in your legs. 

Prevention

The following are some tips to help you reduce swelling in your legs:

• Raise your legs on pillows above your heart when lying down
• Exercise your legs to encourage better circulation
• Reduce the amount of salt in your diet
• Wear support stockings sold at most drug stores
• Stand and move frequently when traveling
• Lose weight if needed

When To See a Medical Provider

Seek emergency care if you feel short of breath or experience chest pain or tightness.

Let your medical provider know if:

• Your leg is swollen, red, and warm
• You have a fever
• You have heart, kidney, or liver problems and suddenly develop swelling
• You are pregnant and have a sudden increase in swelling

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