Spider veins are often considered a cosmetic problem. But they can also be a sign of a more serious underlying condition, such as venous insufficiency or blood clots. Spider veins are usually harmless and don't cause any pain or discomfort. But in some cases, they can be a sign of an underlying health condition that needs to be treated. If you have spider veins and are experiencing any pain, swelling, or other symptoms, it's important to see a doctor to rule out any serious underlying conditions.