The main diseases that cause foot swelling include physiological factors, right heart insufficiency, kidney disease, hypoproteinemia, and may also be idiopathic edema or edema caused by medication, etc. It is necessary to go to the hospital to further clarify the cause and give targeted treatment. 1. Physiological factors: for example, after pregnancy may lead to foot edema. 2. Right heart insufficiency: it may lead to edema caused by blood stasis in the circulation, which can be manifested as edema of the feet. 3. Kidney disease: Kidney disease may cause oliguria, which leads to excessive water in the body, thus causing foot edema, and there may also be excessive protein loss, thus causing hypoproteinemia, leading to edema. 4. Hypoproteinemia: Hypoproteinemia, including that caused by kidney disease and related conditions such as malnutrition, can cause swelling of the feet. 5. Idiopathic edema: In some cases, no clear organic disease can be found, but edema of the lower limbs and feet may occur, which is called idiopathic edema. 6. Drug-induced edema: calcium antagonists such as amlodipine may cause foot edema. Foot edema should go to the hospital in time to identify the cause and targeted treatment.