son admitted abuse, taking suboxone now??

My 22 year old son and his best friend  just admitted they have been addicted to percoset for 2 years.  my son says he's been off them about 1 month and is taking a drug called Suboxone to help him with the withdrawl (withdrawal) effects (he showed me a sublingual strip @ 8mg/2mg).  He has been getting it from someone else who is trying to get off the percosets as well, not from a doctor.  What is the first step I should take to help them?

This all came up because we caught them smoking pot in the garage.  They said it also helps and is not addictive?

Thanks