Many years ago I helped an old friend through detox from heroin. It was a very long 9 days cooped up with him in my flat with other friends keeping us fed and watered and giving me a break for a couple of hours.
I learnt a lot over those 9 days, what really stuck with me was that while he was addicted to the drug, it was the method of delivery, injection that he found the hardest to kick.
He told me “the heroin I can kick, the pin is a lot harder” he did shoot up random things , aspirin, speed, baking powder when he was through the 9 days, simply to fight that side of the addiction.
He dead now though, unfortunately he only stayed clean for a half a year or so.