Depends how pure your gear
is most is cut to fuck if an addict actually got relatively pure heroin they would most likely OD
If some one has a tolerance, they are unlikely to overdose out of nowhere just by doing a little extra heroin.
I use to make my dealer give me my heroin uncut, in rock form, so I could control what cuts I used and knew I wasn't being ripped off. I did this for years and years, along with taking pain killers and never once overdosed. Most of the time I rarely used any cuts at all, cause it was just extra damage to my sinuses. Using uncut heroin made my tolerance grow incredibly quick but I still never ODed from it. But I was also smart about my use and rarely mixed heroin with benzos or alcohol (which I think are two of the biggest culprits in OD deaths). I also stuck to intranasal use and never injected my heroin.
A friend of mine some how managed to keep a heroin habit, a klonopin dependency and was an alcoholic, going for 2 years without overdosing. I worried about her all the time and felt guilty as I was the one who introduced her to heroin to begin with. I'm guessing her tolerance to everything played the biggest role here.
I often get into this debate with people on sites all across the internet, because I'm pro-heroin legalization.
If chronic pain patients can handle high doses of opioids for years and years, there's no reason why an addict wouldn't be able to either.
I would actually venture to say the opposite of what you said Higherfocus420, as in, if some one has pure heroin, they at least know they're fucking around with just pure diacetylmorphine, where as people who get bags full of cuts could have toxic chemicals in them or fentanyl (which is an opioid that you actually can OD on pretty easily if you do too much). But it also would depend on the person and how responsible and educated they are on heroin.
If some one is determined enough to overdose, i'm sure it's possible to do too much heroin and get just that. But a person could also overdose on water if they drank too much of it too.
I think it comes down to tolerance and personal responsibility. People who use drugs but take no time to research them (I use to be this way as a teenager) are the ones who are more likely to have adverse outcomes and events. I would love to see drug reform regarding opiates in my lifetime. At least letting people who are already addicts have access to clean & safe heroin.
For those interested in reading more on this topic -
Drug Truth Australia provides the truth about heroin including heroin overdose, its metabolism to morphine, supervised injecting facilities and naloxone.
www.drugtruthaustralia.org