Numerous components of tobacco narrow blood vessels, making it more difficult for blood to flow through them and damaging artery linings, causing scar tissue to form in the affected areas, which further narrows the artery. Tobacco constricts all vessels and promotes formation of blood clots. All this leads to worsened leg artery blood flow, so the muscles in your legs don't get the oxygen- and nutrient-rich blood they need. That, in turn, causes the pain and cramping of intermittent claudication.