Apixaban is used help prevent strokes or blood clots in people who have atrial fibrillation (a condition in which the heart beats irregularly, increasing the chance of clots forming in the body and possibly causing strokes) that is not caused by heart valve disease. Apixaban is also used to prevent deep vein thrombosis (DVT; a blood clot, usually in the leg) and pulmonary embolism (PE; a blood clot in the lung) in people who are having hip replacement or knee replacement surgery. Apixaban is also used to treat DVT and PE and may be continued to prevent DVT and PE from happening again after the initial treatment is completed. Apixaban is in a class of medications called factor Xa inhibitors. It works by blocking the action of a certain natural substance that helps blood clots to form.