Swollen feet in the 80s may be associated with cardiac failure, deep vein thrombosis of the lower extremities, abnormal liver function, rheumatoid arthritis, and contact dermatitis. 1. Cardiac failure: overloading of the heart due to various reasons and obstruction of blood reflux, resulting in water and sodium retention, which will be manifested as depressed edema in both lower limbs in the clinic. 2. Lower extremity deep vein thrombosis: for some long-term bed-ridden, severely traumatized or undergoing major surgery of the elderly, it is easy to develop lower extremity venous thrombosis, usually one side of the lower extremity is swollen. It may be accompanied by pain and fever. 3. Abnormal liver function: When patients with liver disease are accompanied by hypoproteinemia, edema of the lower limbs may occur, and the main swollen parts are located in the ankles. 4. Rheumatoid arthritis: rheumatoid arthritis is related to type B hemolytic streptococcal infection, which is mainly manifested as wandering pain in some large joints and accompanied by obvious redness and swelling. 5. Contact dermatitis: skin due to contact with some kind of irritating objects when an allergic reaction occurs, will also be manifested as localized skin swelling, accompanied by itching or rashes, blisters and so on. Because the cause of swelling of the feet is more complex, the specific situation needs to ask the doctor for an interview, and combined with other clinical manifestations for analysis.