A Timaru stockist has no qualms about selling synthetic cannabis despite Associate Health Minister Peter Dunne's announcement that all legal highs will soon be dealt "the knockout blow".

Mr Dunne says he will introduce legislation later this year that will reverse the onus of proof of safety, making all psychoactive substances illegal until approved by a new unit within the health ministry. The Government has been applying temporary one-year bans to new substances as they emerge.

All substances will now be cleared from a pharmacological, a toxicological and a clinical point of view before they are allowed on the shelves, Mr Dunne says.

Numerous varieties of synthetic cannabis are available in stores and online.

They include Kush, Tripping Weed, Marley, Pineapple Express and Blueberry brands and retail for between $25 and $35.

The product is designed to produce a feeling of euphoria, similar to that experienced by cannabis users.

Dizzy Spells on Stafford St stocks synthetic cannabis and owner Megan Devries says it is selling well. "We'll keep selling it because it keeps bringing people into the shop."

The store stopped selling pills and powders some time ago because it was too much of a grey area, Ms Devries says.

"We've seen the Marley and Pineapple Express around for some time now," she says. "It's quite good as people would rather smoke it than cannabis because they get drug-tested at work."

Mr Dunne denied new regulations risked pushing the industry underground, because the industry supported a formal regime.

The current approach of temporary bans has seen 28 substances and more than 50 products that contain them taken off the market.

- © Fairfax NZ News