A new study suggests the opioid painkiller hydromorphone may help treat people with heroin addiction.

The study included more than 200 people addicted to heroin who had not responded to treatment with methadone or buprenorphine, HealthDay reports. Participants were randomly chosen to receive injections of either hydromorphone (sold under the brand name Dilaudid) or pharmaceutical-grade prescription heroin, called diacetylmorphine. They received the injections in a clinic, under the supervision of a healthcare professional.

At the beginning of the study, participants used heroin almost daily. After six months, patients in both groups reported using street heroin and other opioids three to five days a month. They also reported a large drop in the number of days they committed crimes—from an average of 14 days to less than four. Almost 80 percent of both groups were still in treatment after six months.

More than 88,000 injections were given during the study. There were 14 overdoses and 11 seizures, all of which were successfully managed in the clinic. The researchers noted these problems might have been fatal if they had occurred on the street.

The findings are published in JAMA Psychiatry.

“Hydromorphone is a widely available licensed pain medication. Our study shows that hydromorphone is as effective as diacetylmorphine, providing a licensed alternative to treat severe opioid use disorder,” lead investigator Eugenia Oviedo-Joekes of the University of British Columbia said in a news release.

Dr. Patricia Daly, Chief Medical Officer at Vancouver Coastal Health, noted that methadone and buprenorphine are effective treatments for many people. She added, “No single treatment is effective for all individuals. Every person with severe opioid use disorder left untreated is at high risk of serious illness and premature death.”