I was a self harmer and a parent of a self harmer.
my daughter was 12/13 when she started and stopped mostly after her father left us both because she could not put that on me alone but there have been a very few very bad incidents in the past 18 months. we have had A LOT of counselling the two of us, I am also a person centred counsellor myself.
I have to strongly but politely disagree with Maggie do not ignore it in anyway let him see that it upsets you.
be honest!! that is the single most important thing I can say, don't pretend don't try and hide your reactions. If this upsets you let him see if you are upset around him.
there are many reasons people selfharm, my daughter calls it an addiction, it was also a cry for attention, it can be a way to fit in with a group, an expression of some greater pain they have no other tools to express or one of a countless range of causes
don't punish him he hasn't done anything wrong. acknowledge, at least to your self, this is his body and his right, I know how hard that is believe me but it is.
.
It is almost always in part a call for attention let it work the reason children do this to seek attention is because it works and it should your son is screaming for attention and he needs it. I know he is hiding in his room and pushing you away. ignoring it will likely lead to an escalation into even more dangerous territory. when a child pushes away our job is to calmly but firmly hold steadily on to them.
Except the other self-harmers in his life. they do understand and yes they except this behaviour, even encourage it by normalising it. but they are the people he is most likely to open up to about this and then come to you if you work on communication.
CBT versus PCT
both have their place and some CBT tricks are incredibly helpful but it is a quick fix and will only fix the symptoms not the cause.
Look for a person centred counsellor for the whole family trust me this is something your whole family will need to address
there are some really good websites for self help CBT
www.getselfhelp.co.uk/links2.htm
Do not take anything away this is punishment to a teenager and that is totally the wrong message, it will also further isolate him. instead insist on more family activities or that the gaming console moves into the living room, ours are and we play xbox instead of watching soaps, move your interests into his area instead of dragging him into yours if he is on facebook get an account and even if you don't friend him, familiarize yourself with it so you know the world he is inhabiting.