What causes leg swelling?

Leg swelling can be caused by relatively minor conditions, such as standing for too long. Leg swelling can also be caused by a wide variety of diseases, disorders and conditions that include infections, inflammation, trauma, heart disease, and other abnormal processes.

In some cases, leg swelling is a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting.

Injury-related causes of leg swelling

Leg swelling can occur from injury-related conditions including:

  • Bleeding
  • Broken bone or leg injury
  • Loose fragments of bone or cartilage within a joint space
  • Muscle, ligament, or cartilage injury,  such as a torn ligament or pulled muscle
  • Repetitive stress injury

Degenerative, infectious, inflammatory and autoimmune causes of leg swelling

Swollen legs can accompany inflammatory, infectious and autoimmune conditions including:

  • Amyloidosis (rare immune-related disorder)
  • Bursitis
  • Gout
  • Infection
  • Osteoarthritis
  • Rheumatoid arthritis
  • Septic arthritis
  • Sunburn
  • Systemic lupus erythematosus

Cardiovascular causes of leg swelling

Leg swelling can also be caused by disorders related to the circulatory system including:

  • Cardiomyopathy (weakened or abnormal heart muscle and function)
  • Cardiovascular disease (due to atherosclerosis or hardening of the arteries)
  • Chronic venous insufficiency (poor blood flow through the veins)
  • Deep vein thrombosis (blood clot in the leg that can break loose from the leg, causing a pulmonary embolism in the lung, a heart attack, or stroke)
  • Endocarditis (infection of the lining inside the heart)
  • Heart failure
  • Heart valve disease
  • Kawasaki disease (rare disease that involves blood vessel inflammation)
  • Pericarditis (infection of the lining that surrounds the heart)
  • Peripheral artery disease (PAD, also called peripheral vascular disease, or PVD, which is a narrowing or blockage of arteries due to a buildup of fat and cholesterol on the artery walls, which limits blood flow to the extremities)
  • Varicose veins

Other causes of leg swelling

Other conditions or disorders that can lead to swollen legs include:

  • Being overweight
  • Chronic obstructive pulmonary disease
  • Fluid retention, such as during pregnancy or premenstrual syndrome
  • Hyponatremia (very low sodium, which is a life-threatening condition)
  • Hypothyroidism
  • Kidney failure
  • Liver failure
  • Lymphatic obstruction
  • Nephrotic syndrome (kidney disorder)
  • Pre-eclampsia (a serious condition marked by swelling, high blood pressure, and protein in the urine that can develop during pregnancy)
  • Pulmonary hypertension

Medications that can cause leg swelling

Always tell your doctor about any medications or treatments you are using, including prescriptions, over-the-counter medications, supplements and herbal or alternative treatments. The following medications may be a possible cause of leg swelling:

  • Antidepressants, such as tricyclics and MAO inhibitors
  • Hormone therapy
  • Diabetes medications
  • High blood pressure medications
  • Steroids

Questions for diagnosing the cause of leg swelling

To diagnose the underlying cause of leg swelling, your doctor or licensed health care practitioner will ask you several questions related to your symptoms. You can best help your health care practitioner in diagnosing the underlying cause of leg swelling by providing complete answers to these questions:

  • Have you experienced a recent animal or insect bite?
  • Have you recently traveled outside the United States?
  • What is the exact location of the swelling?
  • Describe the swelling. When did the swelling start? Does it come and go or is it constant?
  • Are any other body areas swelling?
  • Are you are experiencing any pain, shortness of breath, or other symptoms?
  • Provide your full medical history, including all medical conditions, surgeries and treatments, family history, and a complete list of the medications and dietary supplements that you take.

What are the potential complications of leg swelling?

Complications associated with leg swelling can be progressive and vary depending on the underlying cause. Because swelling can be due to serious diseases, failure to seek treatment can result in complications and permanent damage. It is important to visit your health care provider when you experience any kind of persistent swelling or other unusual symptoms. Once the underlying cause is diagnosed, following the treatment plan outlined by your doctor can lower your risk for potential complications of these conditions including:

  • Chronic disability
  • Chronic pain or discomfort
  • Heart failure
  • Joint instability
  • Kidney failure
  • Liver failure
  • Pulmonary embolism, heart attack, or stroke associated with deep vein thrombosis
  • Spread of infection


  1. Foot, leg, and ankle swelling. Medline Plus, a service of the National Library of Medicine National Institutes of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003104.htm.
  2. Collins RD. Differential Diagnosis in Primary Care, 5th ed. Philadelphia: Lippincott, Williams & Williams, 2012.
  3. Kahan S, Miller R, Smith EG (Eds.). In A Page Signs & Symptoms, 2d ed. Philadelphia: Lippincott, Williams & Williams, 2009.

What is leg swelling?

Leg swelling is a sign of fluid buildup or inflammation of the tissues or joints of the leg. Swelling can occur anywhere along the leg, including the thighs, knees, calves, ankles and feet. Mild swelling is a common occurrence after standing for a long time, especially in warm weather.... Read more about leg swellingintroduction


What other symptoms might occur with leg swelling?

Leg swelling may be accompanied by other symptoms depending on the underlying disease, disorder or condition. For example, leg swelling due to congestive heart failure may occur with shortness of breath. Leg swelling due to an infection may be accompanied by fever, redness and warmth around the affected area. Read more about leg swellingsymptoms

Medical Reviewer: William C. Lloyd III, MD, FACS Last Annual Review Date: Sep 6, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Bones, Joints and Muscles

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