I've never overdosed on heroin but I've overdosed on a weaker opiate called codeine. In strength it's a lot weaker but can still cause severe breathing depression. When I overdosed I stopped breathing for a few minutes, I never got to the point where I turned blue but I felt nothing painful. I was just watching a movie and everything sort of faded away. I could still hear everything that was going on but I wasn't listening. I'm not really sure why I woke up, maybe because I was about to be sick or maybe something really loud happened in the movie, but until I started throwing up the entire experience was completely painless. It was just like going to sleep while you're high. Even if something happened to him that might have hurt, any possible pain he could have felt would be completely overpowered by the pain relief that you get when over opiated. He was peaceful.