An emergency law banning party pills and synthetic cannabis has passed under urgency.
The Psychoactive Substances Amendment Act removes all remaining psychoactive products on the market. It also bans the use of animal testing data in support of product approvals.
The Act is expected to receive Royal assent today and become law at 12.01am tomorrow.
Health Minister Tony Ryall said when the Psychoactive Substances Act was passed last year, some products were allowed to stay on the market.
"The amendment means all interim retail and wholesale licences will be cancelled and all psychoactive products given interim approval will be removed from sale. It will also become illegal to possess and supply the products.
"While animal testing remains a necessary and important component of the process for developing a number of important products, such as medicines, the government does not believe that such testing was justifiable for the recreational drug market."
Approved, low-risk products would be able to come on market in the future when regulations were made, Mr Ryall said.
However, all psychoactive products will become unapproved from Thursday and it will become an offence to possess, supply or sell them.
The penalty for possessing a small amount of a psychoactive substance will be a $500 fine. Possessing a large amount with intention to supply will be punishable by up to two years' jail or a fine of $500,000.
Those in possession of products are advised to return them to the retailer they purchased them from, Mr Ryall said.
Retailers and manufacturers would not be compensated for their losses.
While the psychoactives testing regime would accept overseas animal drug trials which proved that a product was unsafe, such tests would not be able to be carried out in New Zealand to support a product's application.
Mr Ryall said the 41 products which had temporary waivers were not linked to adverse reactions when they were approved last year.
But since the bill passed in August, health authorities had reported an increase in serious reactions including vomiting, seizures and psychotic episodes.
The Government already had power to remove specific products from the market. But because it has been difficult to link cases to individual products, all of them are being removed until a robust testing regime is in place.
- Brendan Manning of APNZ, additional reporting by Isaac Davison