Xarelto side effects bleeding can be fatal. For years, a medicine called warfarin was in use for treating blood clots. People who used to take this medicine had to undergo regular blood tests for measuring how quickly their blood clots. On the other hand Rivaroxaban works in a slightly different way to warfarin and people were not required to make regular blood test. Unlike warfarin, Xarelto is an easy-to-use pill taken once or twice a day. However with time it was noticed that Xarelto side effects have been fatal. Some studies have also linked Xarelto to a higher risk of uncontrollable bleeding for acutely ill patients.