My children do not have it, however my father does as well as some friends. The BEST thing is to continue treatment and medication. When my father was taking medication his moods were so much more stable, but then he would feel as though he was okay and would stop taking his medication. His cycles would be so much worse off his medicine. Now, my father didn't pursue counseling, like he should have, but having lived with someone with the disorder, I believe both medicine and counseling are key to living with the disorder.
Good for you for getting him the help he needs! It is, unfortunately, one of the few "psychoses" and he will not outgrow it. You are his support to help him manage it. It is possible to live a well-adjusted life, but it takes work.
Good luck to you and your son!