Approximately 50% of all patients with a subarachnoid hemorrhage (SAH) die due to the hemorrhage or subsequent complications. There are several major causes for this course, such as in-hospital rebleed in 21.5% which most frequently occurs within the first 6 hours after the primary hemorrhage ("ultra-early rebleed"). A major part of the patients with a rebleed die during hospital admission and when they survive, they develop more severe cognitive dysfunctions. Reducing the rebleeds by ultra-early administration of tranexamic acid (TXA) could be a major factor in improving the functional outcome after SAH.