Some of those users say they feel a measure of security because many of their peers carry naloxone, which can quickly restore their breathing if they overdose.

Data suggest that in San Francisco, drug users may be reversing as many overdoses as paramedics—or more. In both cases, the numbers have risen sharply in recent years.

In 2018, San Francisco paramedics administered naloxone to 1,647 people, up from 980 two years earlier, according to numbers from the city’s emergency-response system.

That compares with 1,658 naloxone-induced overdose reversals last year by laypeople, most of them drug users, according to self-reported data from the DOPE Project, a Bay Area overdose-prevention program run by the publicly funded Harm Reduction Coalition. That’s nearly double the 2016 figure.