Rivaroxaban is an anticoagulant (blood thinner) medication. It is used to help reduce the risk of stroke and blood clots in people who have atrial fibrillation (a type of heart rhythm disorder) that is not caused by a heart valve problem. It is also used to treat deep vein thrombosis (DVT) and pulmonary embolism (PE). Rivaroxaban is in a class of medications called direct thrombin inhibitors. It works by blocking thrombin, a substance in the blood that helps the blood clot.