For many drugs, the worst negative effects are caused directly or indirectly by the drug being illegal. Opiates in general have very limited negative effects on your body - constipation is a common complication. People can br highly functional when using controlled doses of heroine. Morphine is a fairly common analgesic in hospitals because it’s strong, effective and poses little danger.

But needle sharing, the social stigma, the impurities in the drugs, the varying quality, that’s what gets you in the end. And all of these are caused by the drug being illegal, and to address this, you must make drug use legal. That doesn’t mean make it freely accessible in a supermarket, but controlled access like cigarettes and alcohol. Drug use must be treated like an illness, through health and prevention programs, through the medical system. Portugal does so, to great effect.

So if you’re talking about harm reduction bring the priority, then prioritize legalization. It will almost instantly reduce harm.