Remember, kids with ADHD are as much as 30% behind same age peers in development. That means he’s really functioning at age 14-16 level right now probably. That doesn’t mean that he should take advantage and bum around the house and depend on you entirely. He does need to learn independence.
At this point, you probably need to lay down some concrete ground rules for living in your house. No driving unless you take your medicine. You must work at least 20 hours a week. If he has a cell phone, he has to start paying for it once he has a job. Etc…
My understanding is that bi-polar can really wreak havoc on a life when untreated. Try to have a collaborative conversation about his concerns with taking his medicine and see if you can work through some of that. It may be that different medications wouldn’t have as many side effects… or it could be that he just doesn’t want to (denial that he has a condition), in which case you’ll need to tie it to something motivating (like driving, or gaming, or whatever it is for him).
Then, help him find something he’s really interested in or passionate about. That could help him find a job he can stick with, or may even inspire him to get his GED and pursue further education in an area he really likes. This could be gaming – there’s a huge industry now with lots of careers in gaming. Many schools offer a 2-year certification program in different aspects of the gaming industry. My daughter is currently an art major in college, focusing on animation, so she can work at a gaming company. She considered programing specific to gaming, but didn’t have the math aptitude required and found she didn’t really like programming. So many options, you just have to help him find what he’s interested in enough to take action.
ADDitude Community Moderator, Author & Trainer on Parenting ADHD, Mom to teen w/ ADHD, LDs, and autism