Ten people with severe poisoning from synthetic cannabis have been treated at Christchurch Hospital in the last 48 hours.
Nine of those admissions were male and one was female. All patients were aged between 17 to 59 years old.
Of the 10, at least three were admitted to the Intensive Care Unit.
Emergency medicine specialist Paul Gee says it's a trend that has been on the rise for some time.
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," Gee said.
Toxicology analysis identified the substance taken by the recent patients as either AMB-Fubinaca or AB-Fubinaca. AMB-Fubinaca has been linked to numerous deaths in the North Island during the past year.
The Canterbury District Health Board said it was unable to give drug users tips to help identify this lethal drug because the recent patients "were unable to disclose any useful information".
Synthetic cannabis users in Canterbury should be extremely cautious.
The health board said drug and addiction services could be accessed at Tuhauora, Christchurch's Central Coordination Service using this email address: email@example.com.
The Alcohol and Drug Helpline was also available on 0800 787 797.