There are many causes of swollen feet, such as trauma, pregnancy, malnutrition, chronic diseases and vascular factors. 1. Trauma: If the foot is hit or collided by external objects, it can cause redness, swelling, pain and other phenomena, and in serious cases, there may be fractures. 2. Pregnancy: After pregnancy, the uterus may press on the inferior vena cava, resulting in elevated pressure in the inferior vena cava, which may cause body fluids to seep out and be retained in the tissue space, resulting in swelling of the feet. 3. Malnutrition: Long-term nutritional intake is insufficient, which may lead to protein deficiency in the body, resulting in a reduction of albumin in the plasma, thus reducing the effective osmotic pressure and resulting in swelling of the feet, weight loss and other phenomena. 4. Chronic diseases: if you suffer from diabetes, hypertension and other diseases, due to kidney damage, causing sodium retention, which leads to swollen feet. 5. Vascular factors: If the patient has diseases such as deep vein thrombosis of the lower limbs, the blood can be abnormally clotted in the venous cavity of the lower limbs, blocking the venous cavity, resulting in venous blood return obstruction and swelling of the feet. In addition, liver disease, heart disease and other factors can also cause swelling of the feet, it is recommended to go to the hospital in time to find out the cause of the disease, and then follow the doctor’s instructions for treatment.