There has been a shift among injecting drug users towards prescription meds.

A new study published in the Journal of Addiction Medicine has found drug users are injecting benzodiazepines and pharmaceutical opioids like morphine and oxycodone in higher proportions.

Researchers spoke to 50 people from needle and syringe programs across Queensland who had accidentally overdosed in the previous year, nearly all of which had overdosed more than once.

Of those interviewed for the report, half said they primarily injected pharmaceutical opioids like morphine and oxycodone. Heroin and methamphetamines were the next most common, while almost a third had used fentanyl.

University of Queensland Alcohol and Drug Research and Education Centre director Professor Jake Najman said there had been a switch from illicit drugs like heroin to prescribed drugs, though many were mixing both prescribed and non-prescribed drugs.

“This is a group of people who are really quite heavy users and they're grabbing whatever drugs they can get hold of, and clearly it's possible to get hold of a wide variety of drugs,” Professor Najman said.

“Prescribed drugs are readily freely available to people who want to use — so, there is a problem there, it's a serious problem, it's a growing problem and we haven't really managed to deal with it.”

He said drugs were often prescribed for legitimate patients and issues, before other forces helped divert them to the illicit market.

“It's sometimes elderly people who have legitimate needs, for example for painkillers, who will go to a doctor, get a prescribed opiate and then sell that opiate on the illicit market,” he said.

The study also showed an increase in the age of chronic drug users, with some becoming hardened users by the time they were in their 30s.

The Federal Government announced $16 million in funding for a nationwide real-time prescription monitoring system this year, which could help reduce the misuse of some drugs.