Xarelto (Rivaroxaban) overdose. If you take too much Xarelto, you could bleed internally, or hemorrhage. Symptoms of an overdose may include: abnormal bleeding or bruising, bloody or black stools, blood in urine, coughing up blood or vomiting blood. If you or someone else has symptoms of an overdose, call your doctor right away or go to the nearest emergency room. If someone taking Xarelto collapses or isn’t breathing, call 911.