The causes of foot swelling in the left foot are as follows: 1, trauma, strenuous activity or trauma can lead to muscle and soft tissue damage in the foot, which can lead to foot swelling and may be accompanied by painful symptoms. It is necessary to check the foot x-ray to see if there is any fracture, in addition, it is necessary to apply drugs to activate blood circulation and remove blood stasis for treatment, and if the pain is obvious, anti-inflammatory and analgesic drugs can be applied to relieve the symptoms; 2, lower limb vascular diseases, such as varicose veins in the lower limbs, patients with venous thrombosis in the lower limbs, due to poor venous return, there may also be swelling of the feet; 3, cardiac insufficiency, renal insufficiency, and patients with serious liver disease , there is also a possibility of swelling of the feet. When this symptom occurs, it is recommended to go to the hospital for further examination to clarify the cause and for targeted treatment.