Tranexamic acid in trauma: After 3 hours from injury, when is it safe and effective to use again?

Tranexamic acid (TXA) has proven mortality benefit if used early after traumatic injury, likely related to a combination of bleeding reduction and other non-bleeding effects. If TXA is given more than 3 h after traumatic injury, there is a significant and paradoxical increased risk of death due to bleeding. TXA has level 1 evidence for use as a bleeding reduction agent in isolated orthopedic operations, but in polytrauma patients undergoing orthopedic operations, it is not clear if and when TXA is safe or effective once outside the 3-h window of proven trauma efficacy.