Apixaban is used to prevent serious blood clots from forming due to a certain irregular heartbeat (atrial fibrillation) or after hip/knee replacement surgery. With atrial fibrillation, part of the heart does not beat the way it should. This can lead to blood clots forming, which can travel to other parts of your body (such as the lungs or legs) or increase your risk for stroke. In the United States, apixaban is also approved to treat certain types of blood clots (deep vein thrombosis-DVT, pulmonary embolus-PE) and to prevent them from forming again. Apixaban is an anticoagulant that works by blocking certain clotting proteins in your blood.