Since many are cross addicted - and some just prefer AA. And I recommend getting a sponsor, someone who has been there and can contribute helpful advice and guidance. I met mine at my second AA meeting and she helped me so much.
I also used to attend meetings with a guy who was on Suboxone and it really helped him, but last I knew he was still on it.
I know that these are early days for your son, so patience is necessary. It took me six months to put down alcohol for good and even in my sixteenth year, I still attend meetings since I need to remain connected. And I also have made good friends in the program and that sure helps.
I wish your son all the luck in the world, I hope that he wants sobriety this time. And I wish your family support as well, I used to attend Alanon meetings which is for family and friends to support alcoholics/addicts.
Here's the link for Narcotics Anonymous, since meetings which provide advice and support was what worked for me. 
https://usa-na.org/
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