I'll preface this by saying I've never been brought back with Narcan so I don't have first hand experience in that way. But I'm pretty sure being brought back with narcan will put you into withdrawal.
Avoiding withdrawal is the number one motive driving everything I did as a heroin addict. So while I might get Narcan as a precaution to use in friends or for friends to use on me if someone were likely to die. No way in hell would I do anything that I would knowingly think would make it likely to have it used on me.
People don't use intending to OD. Addicts DO NOT use more thinking "oh well if I OD my friends can use narcan on me". I've been a junkie a long long time and been surrounded by junkies just as long. I just do not think any of us think like that.
It would imply not caring much about the idea of waking up in withdrawal after using too much and having to be narcanned. And NO opioid dependent person wants to risk being in withdrawal.
It just wouldn't happen. I don't believe it. The idea that junkies might use more because they have Narcan is the kind of thing you think cause you're NOT a junkie. It reflects a logic you only have cause you don't have hundreds of experiences of being in withdrawal burned into your subconscious making you do whatever you have to to avoid it. Addicts, serious opioid dependant people just don't think like that. They won't generally take risks that end in major withdrawal. Cause they've all been through it too many times already providing an extremely powerful psychological aversion the likes of which you can't comprehend if you've never experienced it.
Sure, you might take additional stupid risks sometimes, but not with that kinda logic behind it. I've never known a serious opioid user who would be that indifferent to the idea of ODing and waking up in withdrawal from Narcan. I haven't even experienced it and the idea of it scares the shit out of me.
So no, I don't buy it not for one second. Most people don't think they're gonna OD to that extent in the first place.
Having Narcan available is only a good thing. I simply don't believe that anyone's gonna go "oh well if I OD it doesn't matter, it only means I'll wake up in excruciating withdrawal so bad I'll wish I'd just died". Yeah right. Not happening.
If Narcan didn't put you into withdrawal by virtue of saving your life, then there might well be some merit to the idea of it causing people to take risks they might otherwise not have. But so long as it ends in withdrawal, I just don't see it happening. No way no how.
What I think it comes down to here is a reflection of how non addicts just don't truly comprehend how strong the compulsion to avoid withdrawal can be. Nobodies gonna play chicken when withdrawal is the price of failure. No freakin way.