Otago police have been visiting retailers selling the synthetic cannabis K2 and asking them to drop the item from their shelves.
Police visited Dunedin K2 retailers last week "and appealed for them to take it off the market", Sergeant Chris McLellan said.
"We realise the dairies are selling a product that is profitable for them, but the reason we are asking them to take the product off the market is all the flow-on health effects..."
These included users becoming highly aggressive, experiencing anxiety and hallucinations. The product was also believed to be a "driver of crime".
"People on the substance are doing things that they would not normally do at other times."
The product had also appeared for sale in K2-only "tinny houses", with two detected in Balclutha and one in Dunedin, he said.
During the weekend, Dunedin police dealt with three youths who had taken K2 and become aggressive and suffered hallucinations.
"[K2] seems to have become quite popular ... Interestingly, I spoke to some cannabis users who tried it and said they would never touch it again."
Retailers, some of whom had been targeted in synthetic cannabis-related crime, had given a mixed reaction about removing the over-18 product.
Some maintained they would continue to sell K2 until it was declared illegal.
Unlike previous synthetic cannabis products- many of which were banned last year - K2 was often bought in bulk over the internet and divided up into smaller amounts for retail.
Last year, police targeted 36 Kronic retailers in the greater Dunedin area, with nine removing the product off their shelves immediately.
Police introduced controlled purchase operations last year, and set up a working group involving high schools, justice and health officials, and which had now turned its attention to K2.
"When we started with Kronic, we felt the product was bad and we maintained that stance right throughout and we tried to educate and provide information ... but K2 has taken it to a whole new level."
Sgt McLellan was interested in talking to anybody who was concerned about K2, particularly any report of youths obtaining the product, or of shops not displaying the product but selling it "under the counter".
"At a national level, we will continue to work with the manufacturers of K2 but also investigate any offences we uncover," he said.
K2 was being tested by health officials, and could join the 28 substances placed under temporary class drug notices, which has led to the removal of 50 synthetic cannabis products from the New Zealand market.