Here is some data which argues against single-drug fentanyl poisoning being a significant contributor to so-called fentanyl overdose deaths:
Vermont's drug poisoning deaths mostly involve fentanyl. In 2019, coroners found that 86% of drug poisoning deaths "involved" fentanyl (link, remove spaces:
https://www.healthvermont.gov/ sites/ default/ files/ documents/ pdf/ DAP_Data_Brief_Opioid_Related_Fatalities.pdf). That same year, Vermont reported that only 17% of drug poisoning deaths "involved" a single substance. If we look at
Scottish data for 2019, we see that in their case, out of those who were considered to have died via drug poisoning "involving" a single substance, 60% of them had two or more drugs in their system. If we assume that the same ratio holds in Vermont, only 7% of drug poisoning deaths would have occurred after consumption of a single substance.
Interesting.
I've had friends who were heroin users for decades, but then died after being given fentanyl and thinking it was heroin (so they took their regular dose).
Although without doing the toxicology myself, I can't say with 100% certainty that, that's what killed them.
But I do have a big feeling that if they had received regular heroin like they were expecting, they'd still be alive.
I use to snort my heroin & was once given fentanyl.
I knew something was different about it because it wasn't brown/tan/grey/white rocks, but just white powder.
There was also no 'vinegar' type smell to it and the taste was nothing like heroin.
I only took a bump about the size of a match head and just that alone had me nodding out within minutes.
And I mean nodding hard. Hard enough that I had to go get my naloxone out just in case.
There was almost no euphoria, barely any histamine release and it was over within 15 minutes.
A week later, my buddy asked me "hey, so how did you like that fentanyl."
I told him never to give me that shit again or i'd kick his ass. lol
And he never did after that.
If that was indeed fentanyl and it took me just that little bit to go into such hardcore nods, I could maybe see how it would kill people, especially so if they also were on benzos/alcohol/etc...
With that said, I had a friend who was an alcoholic and a benzo addict and she did heroin right along side with me and some how she never overdosed either.
So while I'm definitely not saying overdoses aren't possible, I think they're more unlikely than people know, especially with single substance (opioid) use.