The causes of sudden swelling of the feet include physiological causes and pathological causes, such as sitting for a long time, gout attacks and foot trauma. 1. Physiological reasons: For example, if you are sedentary, the venous return of the lower limbs mainly depends on the contraction of the muscles, i.e., the role of the muscle pump to promote its return. Sitting for a long time will reduce the venous return and thus the phenomenon of sudden swelling of the feet. 2. Pathological causes (1) Gout attack: when urate crystals are deposited in the foot, it will cause congestion and edema of local tissues. At the same time, a large number of inflammatory factors are released, causing an increase in vascular permeability and an increase in local exudation, thus causing the phenomenon of suddenly swollen feet. (2) Foot trauma: It can be caused by the local injury of heavy object’s smashing and squeezing, etc. The local exudation increases, which leads to the manifestation of suddenly swollen feet. Heart failure, renal insufficiency and other reasons can also lead to the phenomenon of sudden swelling of the feet, it is recommended that such patients go to a regular hospital, consult a professional doctor, cooperate with the doctor to complete the relevant examinations, to clarify the cause, to avoid blind treatment.