causes of lower leg swellings r Leg swelling caused by the retention of fluid in leg tissues is known as peripheral edema. It can be caused by a problem with the circulatory system, the lymphatic system or the kidneys. You may also experience swelling due to fluid buildup after sitting or standing for a long time. Factors related to fluid buildup include: Acute kidney failure Cardiomyopathy (disease of heart tissue) Chronic kidney disease Cirrhosis (scarring of the liver) Deep vein thrombosis (DVT) Heart failure Hormone therapy Lymphedema (blockage in the lymph system) Nephrotic syndrome (damage to small filtering blood vessels in the kidneys) Pain relievers, such as ibuprofen or naproxen Pericarditis (swelling of the membrane surrounding the heart) Pregnancy Prescription medications, including some used for diabetes and high blood pressure Sitting for a long time, such as during airline flights Standing for a long time Thrombophlebitis (a blood clot that usually occurs in the leg)