Inspired from this thread: Could this be heroin track marks on this model? - Factual Questions - Straight Dope Message Board
What really happens to a vein after it is used for injecting a substance and why it cannot be reused?
It can be reused, just not indefinitely. After a certain amount of abuse, a vein will collapse. The addict then has to find new injection sites in the hands, feet, neck, privates, etc., as QtM noted in the other thread.
It’s not uncommon for states using lethal injection to have extrordinary difficulty getting the IV in due to the condemmed’s drug use. Sme states resort to laying open a vein with a scalpel to facilitate insertion, the so-called “cut-down” method.
I’m a regular donor for Blood Services Canada. Even thought their needle sticks are probably the most sterile around, long time donors are still sometimes told they need to find another vein after years of donations. YMMV, depending out how you scar. Addicts, don’t necessarily get the most skilled or sanitary needles sticks. And the most I could go donate would be every two weeks. A junkie likely shoots up daily.
So it’s mostly a matter of wrecking their veins with scar tissue.
pravnik got it in one. You will also see sloppy junkies with ulcers on their arms from where they just stuck a load in without hitting a vein. It’s gross AND a waste… 
If a vein collapses, doesn’t that mean that some part of their body isn’t receiving blood? Aren’t the major arteries the ones that are used first?
Junkies don’t inject in the arteries, at least not on purpose (they’re heading the wrong way), and there are plenty of other veins to take up the slack. It’s not just constant use that collapses the veins, addicts also inject a lot of stuff that’s not meant for injection (crushed tablets, for instance), that doesn’t do the vein much good either.
There are lots and lots of veins- there will be coverage!
nobody misses a vein on purpose, because if they wanted to do that they would just muscle it. sloppy… lol. right ulcers are gross but addiction is gross.
addiction is gross its not pretty. n its not a matter of being sloppy , thats just part of the junkie life. the farther u go in addiction the worse it gets. no one misses on purpose just to be sloppy. they just cant hit veins and once that starts the ulcers start
Ok, forgive the blatant curiousity, but mysadsong, what the heck were you searching for to find this particular thread? I can’t imagine that it was anything pleasant!
When my Dad had chemo, the injection tube thing was left in his skin full time, even when he was home, so that they didn’t have to keep poking him to give him treatments. Could something like that be used for addicts?
That “injection tube thing” is a shunt. Sure, an addict could probably find a cut-rate medico to install a shunt, and it would be DANDY…for a while.
Even under super-clean protocol, people can develop infections in shunts–after all, it’s essentially an open door through the skin into the bloodstream. Shunt infections can rapidly become fatal.
Addicts aren’t known for sanitary shooting up, clean surroundings, impeccable hygiene, or sterile injectibles. The shunt might provide some really cool highs, right before a fatal infection develops.
~VOW