Many factors can cause leg swelling. Some factors are more serious than others.

Fluid buildup

Leg swelling caused by fluid buildup in leg tissues is known as peripheral edema. It can be caused by a problem with how blood travels through the body. It also can be caused by a problem with the lymphatic system or the kidneys.

Leg swelling isn't always a sign of a heart or circulation problem. You can have swelling due to fluid buildup from being overweight, being inactive, sitting or standing for a long time, or wearing tight stockings or jeans.

Factors related to fluid buildup include:

1. Acute kidney injury
2. Cardiomyopathy (problem with the heart muscle)
3. Chemotherapy
4. Chronic kidney disease
5. Chronic venous insufficiency (CVI). Leg veins have a problem returning blood to the heart.
6. Cirrhosis (scarring of the liver)
7. Deep vein thrombosis (DVT)
8. Heart failure — a condition in which the heart doesn't pump blood as well as it should.
9. Hormone therapy
10. Lymphedema (blockage in the lymph system)
11. Nephrotic syndrome (damage to small filtering blood vessels in the kidneys)
12. Obesity
13. Pain relievers, such as ibuprofen (Advil, Motrin IB) or naproxen (Aleve)
14. Pericarditis (inflammation of the tissue around the heart)
15. Pregnancy
16. Prescription medications, including some used for diabetes and high blood pressure
17. Pulmonary hypertension
18. Sitting for a long time, such as during airline flights
19. Standing for a long time
20. Thrombophlebitis (a blood clot that usually occurs in the leg)

Inflammation

Leg swelling also can be caused by inflammation in leg joints or tissues. Swelling can be a response to injury or disease. It also may be the result of rheumatoid arthritis or another inflammatory disorder. You'll likely feel pain with inflammatory disorders.

Conditions that can cause inflammation in the leg include:

1. Achilles tendon rupture
2. ACL injury (tearing of the anterior cruciate ligament in your knee)
3. Baker cyst
4. Broken ankle
5. Broken foot
6. Broken leg
7. Burns
8. Cellulitis (a skin infection)
9. Knee bursitis (inflammation of fluid-filled sacs in the knee joint)
10. Osteoarthritis
11. Rheumatoid arthritis
12. Sprained ankle