xarelto® significantly lowers the risk of stroke in people with afib not caused by a heart valve problem. it has similar effectiveness to warfarin. warfarin interferes with vitamin k and at least six blood-clotting factors. xarelto® is selective. targeting one critical factor of your body's natural clotting function. for people with afib currently well-managed on warfarin, there is limited information on how xarelto® and warfarin compare in reducing the risk of stroke. like all blood thinners, don't stop taking xarelto® without talking to your doctor, as this may increase your risk of a blood clot or stroke. while taking, you may bruise more easily, and it may take longer for bleeding to stop. xarelto® may increase your risk of bleeding if you take certain medicines. xarelto® can cause serious, and in rare cases, fatal bleeding. get help right away for unexpected bleeding, unusual bruising, or tingling. if you have had spinal anesthesia while on xarelto®, watch for back pain or any nerve or muscle-related signs or symptoms. do not take xarelto® if you have an artificial heart valve or abnormal bleeding. tell your doctor before all planned medical or dental procedures. before starting xarelto®,