I'm wondering what happens if it fails and no medical assistance is sought out.
I haven't heard of that happening. I think that unless you go to a hospital you will die. Unless you take too small a dose.
One person here didn't lose consciousness right away, it took at least 20 minutes, she had called her boyfriend in that time.
But then stopped messaging, so we don't know what happened, whether she survived or not. As I recall, at the end her messaging became very confused as if she was about to lose consciousness.
So as far as I can tell everyone who takes the proper dose does lose consciousness and from there dies, unless someone finds them and gets them to a hospital.