Swollen feet of 90-year-old people are recommended to go to the hospital for further examination, according to malnutrition, lower extremity venous thrombosis, heart failure, trauma and other causes to take appropriate medication, surgical treatment, and so on. 1. Malnutrition: If the edema is caused by hypoproteinemia due to malnutrition after further examination, you can increase the intake of high protein food and elevate the lower limbs appropriately. 2. Lower extremity venous thrombosis: If the swelling is caused by prolonged bed rest, further ultrasound examination is needed to clarify whether it is lower extremity deep vein thrombosis, which can be treated with oral warfarin, intravenous heparin and surgical removal of the thrombus. 3. Heart failure: If cardiac function tests reveal that edema is caused by heart failure or renal failure, cardiotonic and diuretic drugs such as deacetylrhizin can be given appropriately, and hemodialysis can be performed. 4. Trauma: If the foot swelling is caused by sprains, you can rest in bed, immobilize the affected limbs, and use Yunnan Baiyao and other drugs to treat it. Therefore, it is recommended to go to the hospital for further X-rays, ultrasound and other examinations to make a clear diagnosis, and then carry out the appropriate treatment under the guidance of the doctor.