A first of its kind study has found more people are being prescribed antipsychotics, with older women most likely to receive the medications.
The University of Otago study, which spanned from 2008 to 2015, shows the number of those taking antipsychotic medication went up by almost half in less than a decade.
The highest users were European females aged over 65, followed by Māori males aged between 25 and 44.
However, study author psychiatrist Roger Mulder said there was no evidence rates of psychosis were increasing.
"What seems to be happening is these drugs are increasingly being dispensed for things like anxiety, PTSD etc. and this is what's being described as off-label prescribing," he said.
Dr Mulder said the concern is that there isn't studies to show it's safe and effective to use for off-label reasons.
"There are a few small studies that have been done in anxiety, which suggest maybe it does help a bit, but we also know these drugs have side affects and can cause metabolic changes and other changes," he said.
He said he would feel more confident if there was good data.
Dr Mulder said there was also an identical paper under review currently on anti-depressants and they were also on the rise.
"Their rate of increase isn't so fast, because they're already quite high even 10 years ago."
He said there are a lot of people taking these medications, but we don't have good evidence these high rates of prescribing in an overall improvement in people's mental health," he said.