Katie,
I can tell you that my daughter who is 26 so far has kicked heroin and crack addiction for 9 months. She recently had an alcohol relapse. She wasn't really a drinker before.
She lives with me and there haven't been any drug relapses. She works and is trying to get enough money together to move out of my house.
People do kick crack habits everyday. Please don't give up hope. There is hope for your son he just has to want to get better.
Hugs.........Lo