Some prisoners with mental health problems aren't receiving the help they need, due to lockdowns and a lack of medical staff, according to Radio New Zealand.
The claims come from lawyers who say clients of theirs with mental health issues have not been able to get appropriate subscriptions while in prison.
In one instance, a homeless man in a Serco-run prison was meant to be receiving an anti-psychotic drug via injection, but didn't receive it for over a week and appeared in court in a "highly agitated state".
Because of this, the judge did not grant the man the bail he was seeking, because of the way he appeared, lawyer Alex Steedman told the radio station.
Mr Steedman said it wasn't an isolated incident, and that others were also appearing in court without prescribed medication to aid their behaviour.
"I am aware of personal instances with clients that I've had and also talking to other practitioners that seem to confirm that medication is a problematic issue at the moment," he said.
Alcohol and drug counsellor Roger Brooking said one prisoner who was asked to do an alcohol and drug assessment had been on remand in Rimutaka Prison for three months.
Before this, he had been on anti-depressants, but had not received any medicine while being in prison, despite wanting to take it, Mr Brooking told Radio New Zealand.
"He couldn't get to see the doctors; the doctors are only available in prisons part time. There isn't a prison in the country where there's a doctor on duty full-time, so you can have up to 1000 prisoners, and doctors on duty only 20 hours a week."
The lawyers also said there were frequent lockdowns which meant nurses are unable to give prisoners their medication and restricts access to prison health care.