Varicose Veins & Spider Veins: Causes & Treatment Varicose veins are spidery, swollen veins that bump out from beneath the skin. They are usually red or blue and typically appear on the legs, but can also be found in other parts of the body. Smaller varicose veins are called spider veins. Having varicose veins is common, and women develop them more often than men. They are usually harmless, but in some people, they can lead to serious problems, such as leg swelling and pain, blood clots and skin changes, according to the National Institutes of Health. Causes In healthy veins, blood normally flows from the periphery of the body to the centra...