Leg Swelling

Many conditions can cause swelling (edema) in the legs. Some, like venous insufficiency or congestive heart failure are often chronic in nature, while a blood clot or injury can cause acute (sudden) swelling.

This article will detail the most common causes of leg swelling, the symptoms that frequently accompany it, and the diagnosis and treatment options that are available for this concern.

A person's leg is examined for varicose veins by a healthcare provider wearing gloves

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Causes of Leg Swelling

A wide variety of diagnoses and conditions can cause fluid to build up in your legs. The most common ones include:

  • Venous insufficiency
  • Congestive heart failure
  • Acute injury

Venous insufficiency occurs when the veins in the lower extremities cannot effectively push blood back to the heart. This issue is typically chronic in nature and arises when the leg veins become enlarged (called venous hypertension) and their valves cannot close properly.

As a result, swelling in the legs develops, which is usually worse after sitting or standing for long periods of time (called dependent edema).

Venous insufficiency may also occur more acutely if a leg vein becomes blocked by a blood clot (called a deep vein thrombosis or DVT), leading to rapid swelling in one leg.

Congestive heart failure is a condition in which the heart weakens and becomes unable to pump blood effectively throughout the body. This inefficient pumping causes blood to back up in the veins of both legs and pressure to increase in these veins. Ultimately, this built-up pressure results in fluid being pushed into the surrounding tissue and swelling developing in the lower extremities.

An acute injury to one of the soft tissue or bony structures in the leg commonly causes sudden swelling to develop in the affected lower extremity. This type of edema may arise after a ligament is sprained or a muscle tendon is strained. It can also occur if one of the bones in the leg is fractured or if the cartilage in this region is torn or frayed.

What Medications Can Cause Leg Swelling?

Many types of medication can contribute to fluid buildup in the legs. Among the most common drugs that can cause swelling are:

If you are experiencing increased fluid in your legs and are taking one of the medications listed, be sure to speak to a healthcare provider about your symptoms.

Symptoms of Leg Swelling

You may also notice several other symptoms if you have swelling in your lower extremities. These corresponding concerns can help your healthcare provider diagnose the cause of your edema and determine the appropriate treatment.

Some of the most common symptoms associated with leg swelling include:

  • Varicose veins
  • New or healing ulcers
  • Nighttime cramping or aching
  • Focal (in one region of the leg) or sharp pain
  • Shortness of breath when active or lying flat
  • Color changes in the leg(s)
  • Weakness, Instability, or giving way

Varicose veins are a common indicator of venous insufficiency. These twisted and enlarged blood vessels may bulge or protrude outward and are typically located in the ankles, calves, or thighs. Advanced cases of this condition may rarely cause sores or ulcers in the leg, particularly on the inner portion of the ankle.

In addition, both chronic venous insufficiency and acute blood clots can lead to lower extremity soreness, achiness, and cramping, particularly at night. Acute blood clots may also cause sudden warmth or redness in one of the legs.

Because congestive heart failure impacts the ability of the heart to pump, it can also significantly affect your overall activity tolerance. As a result, shortness of breath is common with strenuous activities. It may also be present when you lie on your back at night, making it necessary to sit up while you sleep.

An acute injury to the leg may be accompanied by various symptoms, depending on the affected structure. Bruising, warmth, and redness can develop in the hours or days after the incident. For example, a sprained ankle or broken tibia in the leg will often show immediate swelling.

Your leg may also buckle, give way, or lack sufficient strength if a muscle, ligament, or piece of cartilage is affected. In addition, focal pain (pain in one spot) and soreness are also commonly present surrounding the structure that has been damaged.

How to Treat Leg Swelling

See a healthcare provider for diagnosis and treatment of leg swelling. The treatment will address the underlying condition and will be different for each cause.

The following briefly discusses how the swelling might be addressed, depending on the diagnosis. It is important to follow the treatment advice of your healthcare provider as it will be specific to your condition.

Blood Clot Treatment

Swelling from a blood clot is considered an urgent matter and needs to be addressed immediately with anticoagulant (blood thinning) medication. Seek immediate medical care for sudden swelling in one leg. It may be accompanied by pain and redness or discoloration.

Edema from chronic venous insufficiency is typically addressed with compression stockings or wraps to mobilize the fluid that builds up in the lower extremities and pushes it out of the leg. Regular walking, calf-activation exercises (like heel raises), and pneumatic compression devices may also be beneficial.

Swelling from congestive heart failure is typically treated with a combination of interventions. Avoiding salty foods and abstaining from caffeine can help reduce fluid buildup in the legs.

Medications like diuretics, vasodilators, and angiotensin-converting enzyme (ACE) inhibitors, are also frequently prescribed for congestive heart failure. These drugs are used to combat swelling in a variety of ways, including strengthening the pumping capacity of the heart and reducing fluid retention in the body.

Edema from an acute injury is managed in a different way. Icing, elevation, compression, and rest can help relieve the strain on the affected area in the hours and days after the incident. Over-the-counter medications may also reduce any inflammation or swelling that is present.

For an injury, the underlying damage causing the swelling might be treated with bracing, physical therapy, corticosteroid injections, or even surgery. These will be specific to the injury.

Are There Tests to Diagnose the Cause of Leg Swelling?

A healthcare provider can help diagnose the underlying causes of your leg swelling. To do so, they commonly rely on several different tests, including:

  • Lab tests: Help to identify any abnormal blood values which may help diagnose problems like a blood clot or congestive heart failure
  • Ultrasound: Uses sound waves to visualize disturbances in blood flow and identify venous insufficiency or blood clots
  • Computed tomography (CT) scan: Used to visualize the anatomy of veins when assessing for abnormalities or venous insufficiency
  • Magnetic resonance imaging (MRI): Provides a clear look at the soft tissue structures in the leg when assessing for damage after an injury
  • Electrocardiogram (EKG): Monitors the electrical activity of the heart and how fast it beats
  • Echocardiogram: Looks at how well the heart squeezes

When to See a Healthcare Provider

If you have leg swelling that comes on suddenly over the course of several hours or days, it is very important to be evaluated immediately by a healthcare provider. This is especially true if you have recently had surgery or trauma to the leg, have been hospitalized, or have cancer. Each of these is a risk factor for the development of a blood clot.

Any lower extremity edema that occurs after a leg injury or that is accompanied by shortness of breath requires immediate medical attention. 


Swelling in the leg(s) can be caused by numerous conditions. Most commonly, chronic venous insufficiency is to blame. However, swelling that comes on suddenly may be fro a blood clot or an injury to one of the muscles, ligaments, or bones in the leg. Congestive heart failure can also cause chronic swelling in both lower extremities.

A proper medical workup can help distinguish the causes of your fluid buildup. In many instances, there are noninvasive treatments available that can significantly improve your symptoms. Prompt evaluation and treatment can help you avoid the serious consequences of certain edema-causing conditions. 

Frequently Asked Questions

  • How do I know if I have a blood clot?

    Blood clots cause swelling to develop rapidly over the course of several hours or days in a single leg. They also can lead to leg warmth, redness, achiness, and nighttime cramping. This urgent concern is most common in people who have been recently immobilized in the hospital, who have had leg surgery or trauma, or who have been diagnosed with cancer.

  • Is an infection to blame for my leg swelling?

    Leg infections are most common in people with a recent lower extremity surgery, with ulcers or wounds on their leg, or after an insect or animal bite. In addition to swelling (typically in only one leg), the symptoms of an infection can include leg pain, redness, warmth, and skin glossiness. You may also experience fatigue, fever, nausea, or vomiting.

  • Does eating too much salt cause leg swelling?

    Consuming large amounts of salty or processed foods can cause increased swelling levels in your legs. This is because eating high amounts of sodium triggers your body to retain more water than normal to maintain balanced electrolyte levels. Typically, this type of swelling occurs in the hands and feet and is accompanied by feelings of thirst.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Tim Petrie, DPT, OCS
Tim Petrie, DPT, OCS, is a board-certified orthopedic specialist who has practiced as a physical therapist for more than a decade.