txa in head injury

Hey all

I went to a patient yesterday with a pretty nasty head injury but GCS15 through out and stable vitals and on anticoagulation. I looked up our guidelines for TXA as she was bleeding consistently (not cat haem) and noticed our guidelines indicate TXA for head injury but ONLY if they're are GCS12 or less...

Im struggling to find any info on why you can give it in reduced gcs but not 13 or above. (Currently just reading through crash 3 to double check)

I usually find a learning officer on station or ask a doctor to find out more but neither were around after the job, just wondering if anyone else knew or could direct me to reading, thanks!

I practice in the UK if it makes any difference