I can't speak to heroin withdrawal, but opioid withdrawal was nothing like that for me. Quitting cigarettes was tougher.
I ran out after my surgery because I had plenty left over from before surgery, so I told the surgeon i was good on pain pills. Post-op pain was gone by the time I ran out and I had been reducing the dosage (too quickly as it turned out) on my own so I didn't worry about getting any more. Then I couldn't sleep more than a half hour a night for three days and I figured out I was dependent. Went to my surgeon, told him what was going on, and he prescribed enough for me to taper off without the side effects. Two weeks later I was pain AND drug free.
Easy Peasy.
Quitting cigarettes was hard. I think because it’s a lifestyle and your very body movements are involved. I would move my hand and think of a cigarette.
I finally quit when FR was new to me and my computer system was slow. I’d be involved in a hot thread and I couldn’t be bothered to take my hands of the keyboard long enough to smoke. Thank you FR, lol.