Common causes of swollen feet include factors such as abnormal heart, liver, kidney, and thyroid function. Heart function, liver function, kidney function, and thyroid function all need to be screened to determine their specific etiology. For the elderly, there may be specific causative factors. If there are no abnormalities in cardiac, hepatic, renal and thyroid functions, the possibility of abnormal blood return to the lower extremities needs to be considered, e.g., impaired venous return is the most common cause of swollen feet in the elderly other than organic diseases. Part of the elderly because of less exercise, always sitting, standing or their own exercise ability is poor, it is necessary to consider the possibility of lower extremity blood reflux caused by the possibility of swollen feet. In addition, elderly people with high blood pressure taking antihypertensive drugs, such as diphenhydramine antihypertensive drugs, can sometimes cause double lower extremity swelling, such as swollen feet.