Retailers in New Zealand can legally sell 28 types of synthetic drugs, all of which have been approved by the Ministry of Health.
The Psychoactive Substances Act was introduced in July, but the regulations probably won't be implemented until next year.
The ministry says 28 products, most of which contain synthetic cannabis, have been given interim approval for retail.
Medicines Safety Authority group manager Stewart Jessamine said the approved substances appear to be low risk.
Approved substances had very few adverse reactions reported, and those that had been reported, were deemed to be a low risk of harm.
The ministry estimated that more than 1000 sites were selling synthetic drugs prior the introduction of the act, but since then, Dr Jessamine said, the ministry has approved licenses to fewer than 150 retailers.