Yeah, it's tricky, because most people who overdose won't have the ability to Narcan themselves because they bypass the symptoms and go straight to black out/no breathing. So, it's an interesting question, at what point should one Narcan theirselves? I guess if I was going to Narcan myself, and I didn't slide past the slippery slope into unconsciousness, I would do it when my lips and tounge start turning blue. However, I just don't think most people would have that chance - you'd really have to be slowly bringing up your dose gradually, so with that in mind, hope that helps.