.. please don’t call face slapping non-abusive 

unless someone wants to be slapped in the face as a kink thing.

 then it’s hot

but otherwise no. plenty of ways to make a point to someone who’s panicking or freaking out without having to slap them. Like clapping your hands to make a loud noise to get their attention. 

or y’know. speaking calmly and providing different things that could give someone comfort rather than jolting them out of what could be a very serious reaction

For all you know, face slapping could trigger an even more violent reaction out of the person, or cause more harm in general to themselves and possibly others

just dont do it