According to the National Heart, Lung, and Blood Institute, varicose veins are swollen veins visible just under the surface of the skin. They most often occur in the legs, but they can form in any part of the body.
The National Heart, Lung, and Blood Institute states that varicose veins are an extremely common condition that do not usually cause many symptoms. However, they can be dangerous in some people and cause mild-to-moderate pain, skin ulcers or blood clots. If varicose veins cause issues, they can be treated by a doctor with medical procedures; lifestyle changes might also be recommended.