Dunedin Hospital emergency department clinical leader Dr Tim Kerruish has called for a ban on the sale of Kronic, as it caused "quite significant issues for some people".
"We would support it being removed from sale."Health issues include anxiety and increased heart rates and blood pressure, with one patient suffering seizures as a result of smoking the product.
"There is some consternation among staff that it is available for purchase."The department had not kept any official records on how many patients with Kronic-related issues it had treated, but "it might be worthwhile doing that".
"It must be a fairly potent, active substance," he said.
On Tuesday, Judge Stephen Coyle labelled the sellers of addictive legal highs "amoral", following the sentencing in the Dunedin District Court of a man who grew cannabis as an alternative to the legal substance to which he was hooked.
"While those that sell it do so because it is legal, they do so without conscience," Judge Coyle said.
A Dunedin high school teacher who works with at-risk youth, Marcelle Nader-Turner, called for a boycott on stores selling herbal-high products.
"My preference would be people concerned about this would not go to those dairies, but to boycott them.
"We have to make a public stand and support the dairies who aren't selling it." Secondary schools and youth agencies were struggling to cope with pupils using Kronic, as it appeared the products were marketed directly at youth, with names such as Pineapple Express and Purple Haze.
About 40 Dunedin stores are believed to sell the cannabis substitutes, with several declining to comment on the products yesterday.
On its website, the company behind the product, also called Kronic, says it is "committed to providing responsible adults with ways to relax, kick-back and unwind in a safe and legal manner".
"Our products have always been promoted as strictly R18, and we regularly remind stores and stockists they risk losing the ability to stock them should they violate this."
Associate Health Minister Peter Dunne told the Otago Daily Times he was "concerned about the availability and potential health effects of products such as Kronic, particularly if they were sold to young people".
Retailers had been issued with a warning, reminding them it was an offence to sell to under-18s, with those flouting the law likely to face prosecution under the Smokefree Environments Act.
Mr Dunne said he welcomed the final report from the New Zealand Law Commission on its review of the Misuse of Drugs Act.
Recommendations include improved regulation of psychoactive substances, preventing their importation, marketing and distribution before any approval by a regulatory body.
"I expect the classification of synthetic cannabinomimetics as restricted substances I announced earlier this year to come into effect next year."
NZ Drug Foundation executive director Ross Bell said the products were marketed as an alternative to illegal drugs, but did not disclose what they contained, or give detailed health warnings or dosage limits.
At the very least, the cannabis-substitute industry should limit sales to specialty stores where they could be controlled, rather than making it available to local dairies or video stores, Mr Bell said.
Substances such as Kronic were initially made by scientists wanting to create an alternative to cannabis for medicinal purposes.
"It does seem the New Zealand guys have found a way of getting these chemicals and turning it into a profitable business."
It appeared the same New Zealand product was being marketed in Australia and the United Kingdom as an alternative to cannabis and "they have gone global".
"We don't know what is in the product, there is no research about what the long-term health effects are, and we are unable to give some real, free and factual honest advice to parents."
Cases seen in the Dunedin emergency department were no different from others around the country, raising questions over just what was in the product, he said.
The Western Australian Government was investigating whether to ban synthetic cannabis, following recommendations from health officials and police.
In a recent drug blitz on Western Australian miners, one in 10 tested positive for synthetic cannabis.
Legal highs
• Vegetable matter sprayed with research chemicals called cannabinoids.
• Synthetic cannabinoids mimic the affects of THC, the active compound in cannabis.
• Synthetic cannabinoids believed to be five times more potent than THC.
• Marketed under the name Kronic; sold in ounces, packets, and pre-rolled joints.
