Are bands allowed to mutilate temselves on-stage?

I've recently seen that has badly surprised me. I don't remember the
name of the band or where I have found the video anymore, but there
were some asian teenagers that dressed sorta emo, I guess it was a
Japanese type of rock or emo. Didn't really listened to the sound or
the groove, but it definitely didn't suit my taste. However, they were
on-stage and they were cutting their wrists with blades and then trew
punches in their own mouths until they blidded out. Is it true, or
were there effects? Personally, I don't think those weren't effects,
because they had really cut and hit themselves. It couldn't really
have been a joke. One thing is to see Gene Simmons spitting fake
blood, everybody knowing that it was from the pills, another thing to
hit and cut yourself like crazy.

The thing is, are they really allowed to do that on-stage? And... how
could someone to this? Damn, hitting yourself to blood isn't the best
thing to do on-stage, from every point of view.