Methods, kits and compositions are described that include a non-naturally occurring kallikrein inhibitor and an anti-thrombolytic agent, e.g., an anti-fibrinolytic agent, for preventing or reducing blood loss and/or ischemia, e.g., ischemia associated with perioperative blood loss and cerebral ischemia, the onset of systemic inflammatory response, and/or reperfusion injury, e.g., reperfusion injury associated with cerebral ischemia or a focal brain ischemia, e.g., in patients subjected to invasive surgical procedures, especially procedures requiring cardiopulmonary bypass. Methods are described for preventing or reducing ischemia, e.g., cerebral ischemia, and/or reperfusion injury, e.g., reperfusion injury associated with cerebral ischemia, in a patient by administering a kalliekrein inhibitor.