Spider veins are very similar to varicose veins. Spider veins cause similar problem as varicose veins, except that they are smaller in size. They can be found closer to the skin surface. Spider veins are usually red or blue. They usually occur in the legs, but some people have it also on the face. Spider veins vary in size and they often look like a spider web.
Although varicose veins are in principle harmless, they can in some cases lead to complications. Some of them may have extremely painful ulcers, particularly in the ankles. In such cases you should visit the doctor. Sometimes veins of the leg can extend so hard that cause sudden swelling of your feet. In such case you must ask for medical treatment immediately, because of a blood clot and inflammation of the walls of the vein.