There are many causes of leg swelling, mainly seen in heart failure, liver disease, idiopathic edema, etc., as follows: 1. heart failure: most commonly in right heart failure. 2. kidney disease: such as nephritis, etc. 3. liver disease: caused by liver disease such as cirrhosis. 4. idiopathic edema: some people have leg swelling for unknown reasons, called idiopathic edema. 5. other causes: such as anemia, malnutrition, 5, other causes: such as anemia, malnutrition, hypothyroidism, and the side effects caused by taking some drugs. Among these causes, the most common causes are heart, liver, and kidney diseases. For people with swollen legs, it is recommended to go to the hospital in time to improve the relevant examination, to clarify the specific causes, and to actively deal with the relevant causes effectively, so that the disease can be controlled.