Christchurch Hospital has been inundated by a surge of people with severe poisoning from synthetic cannabis, doctors say.
Seven people, including three admitted to the Intensive Care Unit, were treated by the hospital's emergency department in the past 24 hours.
Emergency medicine specialist Paul Gee says it's a trend that has been on the rise for some time now.
Some of those seeking treatment had minor effects but others were more serious.
Last month, a man suffered a cardiac arrest after using synthetic cannabis but was successfully resuscitated.
"There are dangerous synthetic drugs available and taking them could seriously harm or kill you," Dr Gee said.