There are many causes of bilateral lower extremity swelling, including venous disease, heart or kidney disease, but not related to arterial disease. Generally, lower limb swelling caused by venous disease is mainly unilateral, and the symptoms are light in the morning and heavy at night, and the swelling will be relieved after elevating the limb, and bilateral swelling caused by venous disease is less common. As for heart or kidney disease, it is recommended to go to the relevant department for examination.