SN instructed patient about Xarelto (rivaroxaban) is an anticoagulant (blood thinner) that prevents the formation of blood clots. Used to treat A-fib and lower the risk of a stroke from a blood clot. Side effects include bruising, itching, muscle pain, pain in arms or legs. Serious side effects include: urine that looks red, pink, or brown;headache, dizziness, weakness, feeling like you might pass out;bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds.