Varicose veins are enlarged veins that can be blue, red or flesh- colored. They often look like cords and appear twisted and bulging. Spider veins are similar to varicose veins but are smaller and closerto the surface of the skin. An estimated 30 to 60 percent of adults have varicose veins or spider veins. Varicose veins are typically caused by weak or damaged valves in the veins, while spider veins are most often caused by the backup of blood. They can also be caused by hormone changes, excessive exposure to the sun and injuries. Varicose veins often affect the legs, since they are the farthest from the heart and gravity makes it harder for the blood to flow upward. For many people, varicose veins and spider veins are simply a cosmetic concern. For others, varicose veins can cause aching pain and discomfort. Sometimes varicose veins lead to more serious problems. Some potential causes of varicose veins include obesity, pregnancy, standing for long periods of time, inactivity and hormone imbalance.