when i was first getting into gear i looked into the long term affects of opioids cos i had scientific journal access. fact is. they don't know exactly. you get clean or die. upon autopsy, people who died after using many years of use had brains that were a different texture. they can't do clinical studies cos they wouldn't get ethical approval.
i don't think this is the paper i read originally cos i was only interested in heroin at the time and this is heroin and cocaine, and 2 is a statistically insignificant sample size, but
this has the quote 'extensive spongiform degeneration of the cerebral white matter.' i've known this for almost all of my career as a heroin addict, didn't stop me, but if it gives you some motivation, then ace. don't let it get you down though as that'll spiral into more wanting to use.
also- respiratory problems cos of continuous respiratory depression. this has nothing to do with whether you smoke- i was in rehab with a guy who'd never smoked, who'd found a way to double up his fentanyl prescriptions. he'd been on fentanyl 8 years and was hospitalised twice last winter with pneumonia.
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edit two other things: opioid induced osteoporosis. this actually scares the shit out of me cos i had osteopenia by the time i was 21, close to osteoporosis in my spine. my bones started healing when i started recovering from anorexia, then i got addicted to heroin and now i'm too old for them to get their full density back.
digestive system problems, i think the worst of these heal when you get clean, but i still have problems 9 months into recovery and they're showing little improvement.