I think there are mixed opinions on the matter, it probably comes down to how much damage the hot water does to your skin... I've seen taking a really hot or cold shower suggested as a way to slowly ween oneself off of self-harming behaviors by engaging in less-damaging and/or violent things that still recreate some of the sensation such as holding an ice-cube, eating salsa (which I actually think releases endorphins), or chocolate (same thing with the happy-hormones).

Generally it's considered self harm if you are intentionally inflicting pain or damage on yourself as a symptom of some other extreme or underlying stress.. There are some people who just generally enjoy pain and it's not self destructive or disruptive to daily functioning.

So there are such a variety of factors involved, and I'm still just learning myself.

I hope this was a little helpful, or that someone else on the forum provides better information for you.

Take care of yourself