The veins of the leg have the hard job of returning used blood to the heart. The movements of the legs act as a pump to push the blood upwards against gravity. Standing for many hours a day puts a special stress on them, as does being overweight or pregnant.

Little valves in the veins prevent backflow, but sometimes the valves become damaged.

When the valves fail, blood pools in the legs. The veins become dilated and damaged and fluid leaks out, which causes swelling, aching pain, and fatigue.

Damaged surface veins form unsightly discolored bulges, while deeper veins can develop dangerous blood clots. Everyone with symptoms of varicose veins should get a good medical examination.