what causes varicose veins in legs

Varicose veins are swollen and enlarged veins that usually occur on the legs and feet, particularly in the calves, and may be lumpy, bulging, or twisted in appearance. They are caused by weak vein walls and valves, which allow blood to collect in the veins instead of traveling to the heart, making the veins larger and more visible under the skin. Standing or sitting for long periods can cause blood to pool in the leg veins, increasing the pressure within the veins and stretching the veins, which may weaken the walls of the veins and damage the valves. Varicose veins can cause aching pain, discomfort, itching, and changes in skin color around the affected area. While they are usually not serious, severe varicose veins may cause ulcers, bleeding, and skin discoloration if left untreated.