On the pleasure scale, meth ranks far higher than heroin
What is WORSE with heroin is the severity of the withdrawls, and while reward pathways are screwed up with opiate addiction… after a while the user doesn’t get much of a rush anymore and they are predominantly using to starve off withdrawl.
But aside from the rush, opiates are very good at making your problems go away… they’ll put you to sleep, and during that sleep NOTHING matters…
The reason a heroin addicted individual keeps using despite their friends dying is because the prospect of going through withdrawl is genuinely harrowing… that and most heroin addicts sit atop a mountain of problems… including having to deal with all the nasty shit they might have done while under the influence while trying to get more heroin is slso harrowing.
Heroin is actually just a pro-drug to morphine. What makes it so ‘special’ is… when injected it avoids first pass effect (taken orally, heroin is pro drug to morphine) and it crosses the blood brain barrier VERY quickly. Through a process called deacetylation (heroin is ‘diacetylmorphine’) heroin is quickly converted to two main metabolites… inactive 3-monoacetylmorphine and the active 6-monoacetylmorphine (6-MAM)
6-mam has a very high binding affinity to the u-opiod receptor (receptor largely responsible for analgesia, but also implicated in the development of addiction/feeling euphoric etc).
6-mam also results in a very large histamine release. To an opiate naieve individual this would result in intense itching… to an addict this manifests as part of the ‘body load/high’ associated with H use. Morphine also causes a lot of histamine release…
6-mam may also bind to certain subtypes of opiate receprors that morphine itself doesn’t bind to… the pharmacological significance of this is unknown.
Most ‘heroin’ on the streets today is a mix of fentanyl and xylazine… look up xyalazine… terrifying… actually causes limbs to rot off and shit…
Xylazine is addictive in it’s own way… fentanyl is a very potent opiate. The ‘high’ from fentanyl is purportedly nowhere near as nice as heroin… but the potency of fentanyl is magnitudes higher than heroin… but duration of action is shorter meaning addicts have to use every few hours or less as opposed to 2-4x/day with heroin if using purely to starve off withdrawl.
This means the morphine equivalent dose you’d be dependent on as a fentanyl addict would be magnitudes higher than that of a heroin addict (usually). This usually means withdrawls are going to be even worse.
Some countries still use heroin medicinally. After all… it’s just an opiate.
Getting addicted to injecting morphine, oxycodone etc is just as bad… a lot of ‘how addictive’ an opiate is depends on individualistic predisposition coupled with route of administration (how quickly does substance peak in bloodstream).
So injecting is more addictive than smoking or taking it up the nose… but all of the above provides more of an instantaneous reward than taking it orally or using a patch.
Still… can become dependent or addicted to opiates through ANY ROA provided you take em long enough. I’ve gone through (prescription) opiate withdrawl a number of times (have a prescription for 6-8 months then you go off).
“Drugs of abuse release dopamine. Alcohol, for example, produced a release of dopamine from about 100 units to about 200, You get a similar magnitude of an effect with nicotine. Cocaine produces a huge release of dopamine, from 100 units to about 350 units, however the mother of them all is methamphetamine. Methamphetamine you get a release from the base level to about 1250 units.”
Morphine is around 200 units… I believe IV heroin is around 4-500… keep in mind ‘units’ is arbitrary and there’s more to how pleasurable something is than how much dopamine is released
These units refer to dopamine release in nucleus accumbens (somewhat responsible for regulating motivation/reward seeking behaviour)

If you’ve taken opiates before (in hospital, bad injury, chronic illness, whatever) you’ve PROBABLY noticed there’s nothing THAT great about them.
But if you’ve got serious issues you are trying to run away from… the way they can just put you to sleep would probably be very alluring.
I’ve never had heroin because that isn’t an approved drug in Australia. But through medical administration in hospital i’ve been given IV fentanyl, oxycodone and morphine.
Orally via script i’ve had tapentadol, oxycodone, tramadol, buprenorphine (0.2mg tablets, not the 2-16mg doses used for drug addiction) and codeine.
I’ve also had a script for a buprenorphine patch before.
I can’t comment on street opiates… but there’s nothing particuarly special about prescription opiates if you take them as intended. Any ‘nice feeling’ is pretty much gone within a week after which continually using just works for pain.
Still become physically dependent though and withdrawl (esp if you go cold turkey) isn’t fun… and that’s from doses that are magnitudes lower than what an addict has to withdrawl from…
The vast, vast majority of ‘heroin overdoses’ nowadays are related to fentanyl. The truth is, opiate addicts have less incentive to stop because opiate use provided you aren’t using so much you stop breathing is one of the least harmful addictions you can have in terms of physical damage incurred. With xyalazine the story is different, and fentanyl is very dangerous to be fucking around with… with fentanyl flooding the streets in the USA (and carfentanil) the death rates have spiked
You can blame drug users for this spike in deaths… or you can blame the cartels, dealers and corrupt politicians i.e China, Mexico for pushing fentanyl, carfentanil, protonitazine etc.
But opiates themselves… before fentanyl a LOT of opiate addicts were high functioning (i.e no one knew about their habit for decades… not wife, not coworkers… no one). My cousin was a heroin addict and NO one had a clue until he asked for help because he was sick of being a slave to the drug.
With alcoholism you might feel great… but you can feel how unhealthy it is… with opiates this doesn’t factor into the equation. You don’t feel “unhealthy” aside from constipation, low sex drive, and urinary retention if you are particularly sensitive to side effects. That and they’re very good for reducing physical and EMOTIONAL pain. Someone who is an addict + is using to deal with injuries that would otherwise stop them from working will have a lot of trouble getting off because now they have to suffer egregiously. An addict with psychiatric comorbidities who is self medicating with opiates to numb themselves will never get off until the mental illness is dealt with.