It's when they started cracking down on pharmaceuticals. As it turns out, it's a lot easier to not accidentally kill yourself when all the doses are the same, which is obviously not the case for illicit heroin (it could be with a safe supply initiative though*). This crisis has been made this deadly, make no mistake.

I think it was 2013 that 200% more Americans admitted to using heroin than the year before, and also the year the started taking them off the shelves in stores.

E: Anyone who wants narcan please click here (US only though I think; apologies)