Unilateral swelling of the foot neck can be classified as physiological or pathological. I. Physiological. Due to low eating and lack of high quality protein, if you have recently become anorexic and have swollen feet, this may be the cause. Second, pathological. Lower vena cava foot swelling, mainly due to poor inferior vena cava reflux, is generally manifested as unilateral foot swelling. Third, the climate can also cause swollen feet. When it is hot, most of the peripheral blood vessels of the human body are in a dilated state, so that capillary congestion, so that the skin subcutaneous and soft tissue presents a mild swelling, the same reason as heat expansion and cold contraction. Fourth, there is also heart disease caused by swollen feet, such as nephritis can cause swollen feet. Some swollen feet may be a harbinger of disease and should be taken seriously. In addition, high blood pressure can also cause swollen feet. In fact, there are many, many causes of swollen feet, here are just a few of the most common.