Sudden swelling of the foot is commonly caused by gout attack and foot trauma, as follows: First, gout attack: an acute attack of gout can lead to severe swelling, pain and restricted movement of the foot, and the local skin temperature will also be significantly increased, accompanied by local congestion, and the patient normally cannot bear weight and cannot move. Second, foot trauma: If the foot is hit by a heavy object or sprained, it can cause sudden swelling of the foot, accompanied by pain and limited activity. In severe cases, fractures may also occur, and the presence of fracture lines can be confirmed by taking X-ray films. Early diagnosis and treatment of sudden swelling of the foot can bring the symptoms under control in time; otherwise, it can affect the patient’s normal weight bearing, walking and movement, and affect the patient’s daily life and work. Therefore, after sudden swelling of the foot, the cause of the problem should be clarified and solved as soon as possible.