Friend with a problem...

So a good friend of mine has beginning to develop what i see as a problem. I have noticed him taking pain medication on a regualar basis and i have said something to him on a number of different occasions about it. I have been trying to display my help to him and tell him that these are only going to hurt him in the long run but he believes that theres nothing wrong with what hes doin. It hurts to see someone fall into the trap but i feel that as long as i am here for him and just keep reminding him that what hes dong is going to hurt ihim. I care a lot about my friend andi just dont wanna see something happen. These situations suckk. Any advice just coment thanks