A new study shows a growing number of synthetic cannabis users are being admitted to psychiatric care.
The study published in the New Zealand Medical Journal shows 13% of all patients admitted to Dunedin Hospital's psychiatric ward over a period of three-and-a-half months were using synthetic cannabis
Researcher Chris Gale says some of those had pre-existing mental health issues, but others developed psychiatric problems at the same time they started using the drugs.
Mr Gale says it is likely psychiatric wards throughout the country are experiencing a similar increase in patients and that will be stretching health resources.
The study of 162 admissions says patients using synthetic cannabis tend to be more aggressive, suicidal, and in one case, homicidal.