Pradaxa (Dabigatran) is used to prevent stroke and harmful blood clots (such as in your legs or lungs) if you have a certain type of irregular heartbeat (atrial fibrillation). Dabigatran is also used to treat blood clots in the veins of your legs (deep vein thrombosis) or lungs (pulmonary embolism) and to reduce the risk of them occurring again. This medication may also be used to prevent these blood clots from forming after hip replacement surgery. Dabigatran is an anticoagulant that works by blocking a certain substance (a clotting protein called thrombin) in your blood. This helps to keep blood flowing smoothly in your body. Dabigatran should not be used to prevent blood clots from forming after artificial heart valve replacement. If you have had heart valve surgery, talk to your doctor about the best medication for you. Do not stop taking any medication, including dabigatran, without talking to your doctor first.