Varicose veins are enlarged and swollen veins that can be visible, just under your skin, where they become dilated and stretched out as a result of high pressure inside the veins. They are dark purple or blue in color and can appear twisted and bulging, often like cords. They are considered a true medical problem because they cause pain, throbbing, aching, tiredness, heaviness, swelling, itching, leg fatigue, cramps, restless legs syndrome, and skin discoloration.