VANCOUVER, Canada — Walking back alleys in Vancouver’s impoverished Downtown Eastside, Kevin Thompson, 43, tells stories from roughly two decades of cocaine and heroin addiction.

Drug deals would sometimes go bad, and he was robbed and assaulted. One notable incident involved a fight over a waffle iron that ended with a golf club being broken over his head. “It can be a lot of hassle just to get what you need for the day,” Thompson recalls.

But even trouble-free buys weren’t much of a relief. A high never lasts long enough, he explains.

Life often consisted of little more than scrounging for money or shoplifting, getting through a drug deal, injecting cocaine or heroin, and then doing it all over again a few hours later. Years went by like that, always waking up anxious, enduring the early symptoms of withdrawal until he could find the next fix.

Thompson was finally able to break away from the risks and complications of scoring drugs on the street, he says, thanks to diacetylmorphine, or prescription heroin.

Thompson participated in two studies that provided access to the drug, which is administered following the protocol of a traditional treatment, like methadone. There was the North American Opiate Medication Initiative (NAOMI) from 2005 to 2008, he says, and the Study to Assess Longer-term Opioid Medication Effectiveness (SALOME), in which he participated in 2013. Three times a day, Thompson explains, he would visit a clinic in Vancouver’s Downtown Eastside, receive a free dose of pharmaceutical heroin and leave, without having to worry about where his next fix was coming from. Heroin maintenance, as this sort of therapy is known, falls into a category of public health policies called harm reduction, a bold strategy that Vancouver has long championed.