Pradaxa helps to prevent platelets in your blood from sticking together and forming a blood clot. pradaxa is used to prevent blood clots and to reduce the risk of stroke in people with a certain type of heart rhythm disorder. pradaxa is also used to treat or prevent blood clots in the veins of your legs (deep vein thrombosis, or DVT), or the veins in your lungs (pulmonary embolism, or PE).