Swelling of feet after chemotherapy can be caused by renal insufficiency, hypoproteinemia, deep vein thrombosis of lower limbs, and high fluid intake. 1. Renal insufficiency: after self-factors or application of chemotherapeutic drugs, poor renal function can occur, glomerular filtration rate decreases but tubular reabsorption function is normal, sodium retention can occur due to tubulo-glomerular imbalance, which can be manifested as swollen feet. 2. Hypoproteinemia: Due to the decrease of eating ability, insufficient nutrition of the body, or the decrease of albumin synthesizing ability caused by the abnormal liver function, the albumin level can be decreased, causing hypoproteinemia, and the body will have swollen feet due to the increase of leakage fluid. 3. Lower extremity deep vein thrombosis: when lower extremity deep vein thrombosis and other vascular diseases occur, blood vessels are narrowed and blocked, resulting in venous blood return obstacles, and blood stagnation in the feet can appear swollen. 4. High fluid intake: When chemotherapy treatment is performed, a large amount of fluid may enter the body, and the imbalance between fluid intake and output leads to an increase in water load in the body, which may result in swollen feet. Swelling of the feet after chemotherapy should be promptly consulted and appropriate treatment should be carried out under the guidance of specialists, which will help to alleviate the uncomfortable symptoms as soon as possible.