7 Possible Causes of Swelling in Only One Leg: A Complete Guide

Swelling in one leg can be caused by conditions like deep vein thrombosis, chronic venous insufficiency, or lymphedema. It may also result from infections, injuries, or other underlying health issues that require medical attention.

If you or a loved one notice swelling in just one leg, you may wonder what's causing it. The swelling can be uncomfortable or painful and can be especially worrisome if it's happening only on one side. Swelling, sometimes called edema, can have a wide range of causes ᅳ some minor and others that need more immediate attention. 

The team of specialists at CardioVascular Health Clinic leads the country in innovative, comprehensive treatments for cardiovascular diseases and conditions that can cause leg swelling in only one leg. With national-caliber physicians, interventional radiologists, and cardiovascular specialists, as well as state-of-the-art facilities and diagnostic technology, CardioVascular Health Clinic provides the comprehensive care you need for unilateral (one-sided) leg swelling, so you can lower your risk of complications and experience better health outcomes.

7 Reasons Why Only One Leg May be Swelling

Swelling occurs when fluids build up in the tissues of the body. When it happens in only one leg, the causes are often a problem with your blood vessels, lymphatic system, or soft tissues in that specific leg. It's important to note that there are many causes of significant or persistent swelling. Some of them are more urgent than others, so it's always a good idea to get checked out by a healthcare provider. 

Here are some of the most common causes of swelling that might happen in only one leg. 

1. Deep Vein Thrombosis (DVT) 

Deep vein thrombosis (DVT) is one of the more serious causes of swelling in one leg. DVT is a blood clot that forms in a deep vein, often in the leg. It is a potentially life-threatening condition because if the clot breaks loose, it can travel to the lungs and cause a pulmonary embolism. 

Signs of DVT may include: 

• Pain in the affected leg 
• Warmth around the swollen area 
• Red or discolored skin 
• A heavy or achy feeling in the leg 

DVT requires prompt medical attention and treatment. If you notice the above symptoms, seek medical care immediately. Tests, such as an ultrasound, will help your doctor diagnose the cause of the swelling, and if it is DVT, they will recommend treatments to prevent the clot from causing further harm. 

2. Chronic Venous Insufficiency (CVI) 

Another common cause of one-leg swelling is chronic venous insufficiency (CVI). This condition is where the valves in your veins don't work as they should, leading to poor blood flow. Blood will pool in your leg instead of traveling back to the heart, which causes swelling and discomfort. 

Symptoms of CVI include: 

• Aching or heaviness in one or both legs 
• Varicose veins (swollen, twisted veins) 
• Skin changes, such as discoloration or thickening 
• Sores or abscesses on the leg that don't heal (in more advanced cases) 

CVI is not life-threatening and tends to develop over time. But, it can become uncomfortable ᅳ even quite painful ᅳ and affect your quality of life. Compression stockings, lifestyle changes, and certain medical treatments can help manage your symptoms and improve your blood circulation. 

3. Lymphedema 

Your lymphatic system helps drain fluid from tissues. If it becomes blocked or damaged, you may develop lymphedema. This can cause fluid buildup and swelling, often in just one leg. Lymphedema can develop after certain surgeries, cancer treatments, infections, or injuries that affect the lymph nodes. Sometimes, it can also be congenital (present at birth). 

Signs of lymphedema include: 

• Persistent swelling that doesn't go away with rest 
• A feeling of tightness or heaviness in the leg 
• Thickened or hardened skin over time 
• Recurrent infections in the affected area 

Unfortunately, there is no cure for lymphedema. However, it can be kept under control by wearing compression garments, and with specialized exercises and lymphatic drainage therapy. It's important to get treatment early to prevent complications and improve your mobility. 

4. Injury or Trauma 

Sometimes, an injury to your leg may cause swelling. Some injuries that cause swelling and discomfort include sprains, strains, fractures, and even bruises. Usually, an injury is noticeable when it happens. But sometimes when you've been active, swelling can occur without an immediate, apparent injury, like when you bump into an object and later wonder where that bruise came from. 

Injury-related swelling is often accompanied by: 

• Pain or tenderness 
• Difficulty bearing weight on the leg 
• Bruising or redness 

For a minor injury ᅳ a bruise or a mild sprain ᅳ the RICE method (rest, ice, compression, and elevation) can help reduce swelling. However, if the swelling is extreme or you can't move your leg or put weight on it, you should seek medical care to rule out a more serious injury. 

5. Infection 

Infections can also cause swelling in one leg. Cellulitis is a bacterial infection of the skin and soft tissues. Anyone can get cellulitis through a cut or break in the skin, but those with poor circulation or a weakened immune system may be at a greater risk. Cellulitis can spread rapidly, so it's important to get it treated. 

Symptoms of cellulitis include: 

• Redness, warmth, and tenderness in the affected area 
• Fever or chills 
• Rapidly spreading swelling 

Cellulitis will require treatment with antibiotics to keep the infection from spreading to the bloodstream or other parts of your body. If you think you might have an infection, it's vital to see a healthcare provider right away. 

6. Peripheral Arterial Disease (PAD) 

Peripheral arterial disease (PAD) is a condition where plaque builds up in the arteries in your legs, causing them to become narrowed or blocked. PAD generally causes cramping or pain in the legs when walking. However, it can also lead to swelling, especially if the blood flow is significantly reduced. 

Other signs of PAD include: 

• Pain or cramping in the leg muscles (especially during physical activity) 
• Skin on the affected leg may be pale or cool to the touch 
• Pulses in the leg or foot may be weak 
• Wounds or sores on the leg that are slow to heal 

PAD is a serious condition that can increase your risk of heart attack or stroke. If you experience these symptoms, visit your healthcare provider. They can perform tests to assess blood flow in your legs and recommend lifestyle changes, medications, or procedures to improve circulation. 

7. Other Causes of Swelling in the Leg 

The causes listed above are some of the most common reasons for swelling in one leg, but there are some other potential causes, which include: 

• Baker's cyst: This is a cyst behind the knee that is filled with fluid, and which can cause swelling down into the leg. 
• Tumors: In rare instances, there can be a tumor pressing on blood vessels or lymph nodes. This can cause swelling in the leg or foot. 
• Medications: Some medications can cause you to retain fluids or cause swelling. Examples: steroids, calcium channel blockers (blood pressure medication)

A healthcare provider can help determine the underlying cause of unexplained or persistent swelling in your leg and provide the appropriate treatment. 

When You Should See a Doctor About Swelling in Only One Leg

Not all cases of leg swelling are serious, but sometimes, it may be a symptom of a more urgent condition. You should seek medical care if: 

• The swelling comes on suddenly or is severe. 
• You experience pain, redness, or warmth in the swollen area. 
• You have a fever or other signs of infection. 
• The swelling doesn't improve with rest or home treatments. 

Consult With the Experts at CardioVascular Health Clinic for Your Leg Swelling

Swelling in one leg may result from many different things, from minor injuries to more serious conditions like DVT or infections. If you or a loved one is experiencing leg swelling in only one leg, it's important to take it seriously and consult an expert. At CardioVascular Health Clinic, our team of vascular and cardiovascular specialists can help diagnose the cause of your swelling and provide personalized treatment to help you get back on your feet. 
Remember, early intervention can make a big difference in your health and well-being, so don't wait to seek care if you're concerned about leg swelling. Schedule your consultation with CardioVascular Health Clinic today.