Otago-Southland coroner David Crerar said he was concerned about "an apparent drug subculture surrounding DHB facilities" in his findings on the death of Dunedin man Sean Robert Walsh (31) last December.
Mr Crerar found Mr Walsh overdosed on illegally obtained methadone while he was an inpatient of one of the district health board's mental health wards. Mr Crerar recommended the board give "specific attention ... to the illegal supply, by members of the public, of drugs to patients at SDHB facilities".
His findings noted, at the time of his death, which occurred when he took the methadone on top of his prescription drugs, Mr Walsh was staying in ward 11 at Wakari Hospital under a community treatment order.
The ward was not locked and patients were allowed unescort-ed leave into town.
Mr Walsh, who had mental-health issues for much of his life, was a known drug and alcohol abuser, but ongoing counselling was not considered useful as he did not recognise the substances were harmful to him.
It said police evidence was that the source of the methadone was never established, but that Mr Walsh most likely got it in town the day he died, while he was on day leave.
In his findings, Mr Crerar said he arrived at his opinion there was an issue with illegal drug dealing to hospital patients after receiving evidence to that end from police, the Walsh family's support person, and the board.
At an inquest hearing last month, Constable Keiran Young gave evidence there was a small illegal market for methadone along with other prescription medication, "within the Dunedin community".
The Walsh family's support person, Fiona Panirau, from the Schizophrenia Fellowship, said she told the hearing she believed there was a "huge problem" with drug suppliers taking advantage of mentally ill people, and it was happening inside and on the grounds of Wakari Hospital, as well as across Dunedin.
She said she had since written to the coroner to clarify she had not meant it imply there was a specific issue with the hospital.
In his findings, the coroner acknowledged Ms Panirau's letter.
After reading the coroner's findings, board mental health medical director Dr James Knight told the Otago Daily Times he would not go so far as to say there was a "drug subculture".
Substance use was common social behaviour and substance abuse a common problem, so it was not surprising mental health service patients used substances and sometimes brought them into hospital or were supplied while being treated as inpatients.
Police were contacted if patients were found with illegal substances, or if people were suspected of supplying illegal substances to patients in the hospital.
On rare occasions, people had been banned from hospital grounds when they had been found to be supplying substances to patients.
Some patients who were known to use drugs might be required to provide urine samples for drug screening.
Dr Knight emphasised that, in patients' treatment plans, education on substance use was the main strategy, rather than control and monitoring.
Counselling regarding substance abuse would be offered in an attempt to reduce the harm caused.
Dunedin police hospital liaison officer Senior Constable Robert Murray said police had been contacted about people supplying illegal drugs to patients at or around Wakari Hospital only "a handful" of times in the past four years.
He was not aware of any particular problems around the hospital with drug supply, he said when contacted.
Mr Crerar said he was disappointed to learn some people in Dunedin were preying on the most vulnerable members of society.
"Sean Walsh died because somebody supplied him with an illegal drug. I hope that steps will be taken to limit or eliminate such supply in the future."
He recommended the police and the board learn from the circumstances of Mr Walsh's death and take action to avoid the recurrence of deaths in similar circumstances.
