Invercargill police say tests have not found any illegal substances in the synthetic cannabis product known as Kronic.
The Drug Foundation is concerned that teenagers younger than 18 are getting high on Kronic, which can only be legally sold to adults, and that it is not clear what its ingredients are.
The Area Commander for Southland, Inspector Barry Taylor, says testing of Kronic was conducted by the Institute of Environmental Science and Research.
Mr Taylor says its ingredients were found to be legal, and it appears police have no power over its sale and supply.
He says concern from the community has prompted him to seek advice from Police National Headquarters on how to deal with Kronic.