People seeking help with psychoactive substance are referred to Care NZ Addiction Service.
Where there were also mental-health issues, the DHB's mental-health services worked alongside Care NZ to support recovery, said Mr Fairley.
New Zealand Drug Foundation executive director Ross Bell said some people had continued to use psychoactive substances after the ban. Synthetic cannabis was on the black market alongside new products.
"The added challenge is that people can also buy these substances online and have them posted from overseas," said Mr Bell.
A thriving black market for the drugs had always existed.
"If people want to get their hands on substances, then they still can."
The psychoactive substances law as it first passed had been "brilliant" and should have gone a long way to giving the Government greater control over the drug market, he said.
However, the amendment removing products with interim approval from sale meant the Government had handed control to the black market: "Users of these products are at real risk now because the black market doesn't care for consumer protection. It doesn't care for potency or dosage or quality control."
The Psychoactive Substances Act could work if somebody in the industry was willing to develop a product, put it through the testing regime and get it approved for legal availability.
"Until then, we're left with this mess where there is a whole lot of unknown and very risky substances on the black market and we're seeing problems being reported in A and E, people reporting seizures and that kind of stuff."
However, Mr Bell said a black market would exist even if the act was working perfectly.
"It wasn't ever going to be a law that solved all of New Zealand's drug problems but I think it would have gone a long way to reducing some of that harm."
Mr Bell said some people had stopped using the substances since the ban came in and had swapped to others such as alcohol and cannabis.
Many of those who had bought psychoactive substances because they were legal had stopped after the ban, "but the market's still pretty thriving".