A 31-year old man has been arrested in Hamilton and accused of selling psychoactive substances, the first arrest since the drugs became illegal at midnight on Wednesday.
Police responded to a call to a motel on Thursday night and said they found the man and his female partner in possession of 196 packets of unsold product and $680 in cash.
They said the man told them he had purchased the packets in Auckland for $10 each and was selling them for $20.
He has been charged with selling a prohibited substance and will appear in the Hamilton District Court.
Watch young people talk to The Wireless about the law change
The Psychoactive Substances Bill made it an offence to sell, supply or possess the products. Possession of even a small amount is punishable by a $500 fine.
Call, patients increase
Since the law came into effect, Waitemata District Health Board has noted an increase in the number of people presenting with effects of the drugs, but not as many as expected.
Clinical director of community alcohol and drug services Susanna Galea said there had been a rise of about 20 percent in the number of cases.
She said there had been a noticeable increase in the number of calls from family and friends of users, as well as from health practitioners, asking for advice.
The Alcohol and Drug Association said calls to its helpline had increased since synthetic drugs became illegal.
Chief executive Paul Rout said there had been a moderate increase in the number of calls to the Alcohol Drug Helpline, with 18 on Thursday specifically about synthetics.
In general this week calls had increased about 63 percent over last week and overall calls had doubled about synthetic drugs since the withdrawal from retail shelves was announced.
Mr Rout said the calls were split between those seeking help for themselves, and family and friends seeking advice on helping others.