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This week, Newstalk ZB has been hearing from people who have had their lives ruined by the substances.
One caller, Jayden, told Chris Lynch his addiction got him admitted to Christchurch's Hillmorton Hospital.
However, he soon discovered the substance was being circulated among patients.
"The units were split into north, south, east and west and I was in east and they were smoking it in there.
"People were selling it and supplying it and swapping their medications for it," he said.
The use of drugs in the hospital has since been confirmed by the CDHB - general manager specialist mental health services Greg Hamilton said units at Hillmorton are open, and consumers are free to come and go.
However, several measures have been undertaken to address the issue of banned items, including drugs.
"This has involved modifications to increase visibility, create a safer campus, and reduce areas where contraband can be hidden," he said.
Jaydon told Chris Lynch he thinks it is not good enough.
"You used to be able to go to a government hospital to get away from it. Not for it to follow you.
"That's the whole point, to get away from it. Yes, it's readily available in the community and things need to change but there needs to be a focus on keeping it away from the hospital."
He said he has battled with drug and alcohol addiction his whole life.
"I entered the criminal justice system and I chose the enter it because there was no help."