In fact the only think you can do is report this if he is a potential harm to himself or others.
Since he has threatened harming himself, he can be put on a 3 day hold for hospital evaluation. His doctor can initiate this, for example.
If it is determined that he truly is at risk, the medical hold can be extended.
This is really not a self help situation in terms of what you can do, as he is 27.
If he wants help, then finding him an addiction medicine specialist would be the best avenue.
OK, so that is an initial answer…. Please use reply to expert if you have further questions. When you are ready, please click a positive rating [hopefully excellent]. If you forgot something, come back. I am here daily.