The tourniquet should not be on too tight, or left on for too long, as this causes the veins to swell and stretch. When injecting, the needle's bevel or "hole" should face upward and be eased into the vein at a shallow angle between 10 and 35 degrees to minimize the risk of penetrating through the vein entirely. In order to prevent stress on the vein, the needle should be pointing towards the heart.[14]