The veins job is to bring blood back to the heart. The problem is that veins are fighting against gravity, which is trying to pull the blood to your feet. The way the veins counteract this is that they have one-way valves in them. The valves close as the blood passes toward the heart and they do not allow blood to back up toward the feet. In some people, the valves wear out over time and this allows for blood to stay in your legs longer than normal. Over time, this leads to a buildup of pressure in the veins. This increased venous pressure causes a feeling of heaviness and tiredness in the legs. As the pressure increases, abnormal superficial veins arise and can be seen on the skin. These can be large bulging veins or smaller veins looking like spiderwebs, called telangiectasias. These veins are called varicose veins and they can be painful or cause itching. Eventually, the increased venous pressure can lead to swelling and discoloration of the legs and if left untreated, can predispose you to developing venous ulceration and venous inflammation, called phlebitis.
People that spend most of their time in the seated or standing position are most at risk. Teachers, hairdressers, and people whose job requires them to be standing for extended periods of time are frequently affected. Females are more at risk than males due to the female hormones that circulate. In addition, pregnancy and childbirth put excess stress on the veins. Excess weight will also put stress on the veins and increases risk for venous insufficiency. Prior history of blood clots can damage the valves and lead to venous insufficiency. There is a hereditary component as well, so if your relatives have had varicose veins and venous insufficiency, you are at a higher risk for developing the disease.