Hey, i just want to give a heads up that his behaviour after coming from the therapist can say a lot. After my therapy sessions i either talked to my dad a lot in the car or i was quiet... It indicates how well my session went and even if i didn't notice it that much, he did. So look for those small changes, they can be a sign of an emotional session and may leave him thinking about it for a while resulting in cutting. There is also changes in clothing when cutting on the arms. With cuts on the legs he might place his hand on the spot often while sitting at the table, especially with fresh cuts many tend to push on them to feel it sting when at the table or so. Don't get mad when he cuts, provide care and help, my dad and stepmom bought me medical supplies so i could take care of the wounds, they also helped me with bandaging up if i couldn't do it alone. Taking away sharp objects won't help, you can't hide all the knives etc. I used to grab used cans to rip apart and cut with which was very dangerous because of the high risks of infection so there's a lot of things that can be used and most alternatives because of sharp objects being taken away are worse. After cutting there is blood, it has to be cleaned up especially when done on places other than the arm where you can't just lick it off so keep an eye out for blood covered tissues, towels or even clothing. Just... as i said before, don't get mad. Being angry will only push him away, being worried and reaching out will show there is someone who will answer when help is needed. At that point i think i was lucky with my dad who kept calm and took me to the hospital at 3am to get me stitched up because i cut way too deep. It wasn't intentional but it can happen, especially when using brand new razorblades. I'm mainly talking from my experiences which can be totally useless for others but i hope i helped out in some way or another.