How to take Xarelto (Rivaroxaban). Take Xarelto exactly as prescribed by your doctor. Xarelto is taken either once per day or two times per day, depending on the reason you are using this medication. For atrial fibrillation: Take the Xarelto 15-milligram or 20-milligram tablet once per day with your evening meal. For blood clots in your legs or lungs: Xarelto is usually taken with food 1 or 2 times per day, at the same time each day. For hip or knee replacement surgery: Xarelto 10-milligram tablet once per day with or without food.