More than 60 per cent said synthetics were "very easy" to get.
The average cost of a gram of synthetics last year was $17 - the cheapest of the four centres. It cost $24 in Wellington, $22 in Whangarei and $19 in Auckland.
In Christchurch, 18 per cent said synthetics were the substance responsible for their drug-related harm.
The statistics come after police revealed they believed about 20 people may have died from synthetic drugs.
Synthetic cannabis was banned in 2014. Since then, a black market had been formed to distribute and sell it.
The survey found the use of synthetics was on the rise in Auckland, Whangarei and Wellington as well.
Detective Inspector Greg Murton said targeting the manufacturers and suppliers of synthetic drugs was a "major priority" for the organised crime squad and offender prevention team.
"We are engaging with outside agencies and counselling/drug support services to assist users to overcome addiction."
Christchurch Hospital emergency department clinical director David Richards said there had been no known deaths from synthetic drug use.
"At the present time, we don't have the ability to accurately collect the data re numbers of synthetic cannabinoid users presenting to ED but, anecdotally, numbers are increasing and users when spoken to are stating they are dependent upon them and it is relatively easy to obtain."
Richards said there had been a small change in the side effect profile of synthetic drugs with some people, which could indicate there was a new substance or ingredient around.
"Some people are showing increased agitation and confusion, and a few people have suffered seizures. We are also seeing cyclical vomiting from both natural cannabis and synthetic cannabinoid."
Drug-ARM manager Geoff Howard said it had seen a shift in the demographic of people using synthetics and seeking counselling and support services.
He said prior to synthetics being banned in 2014, a wide range of people were using them.
Now, people who were already using other drugs were becoming larger users, he said.
"It's a shocking drug; it's very physically addictive," Howard said.
"I've definitely seen a reasonable spike in people we're seeing presenting with: I want help getting off synthetic cannabis."
But he said there had been a larger spike in those seeking help for the "powerfully additive" methamphetamine.
He said: "Now it's horrendous."
"There's a lot of money in it, that's the big thing."
The study said meth had become easier to get and cheaper in Christchurch. The price of a gram was $1120 in 2014, and $765 last year. According to the latest figures, last year 32 per cent said they used it, up from 20 per cent in 2012. But the 2016 figure had reduced slightly from the year prior.
In 2011, 31 per cent said they could get the drug in an hour or less. That increased to 66 per cent last year. Although that did drop from about 75 per cent in 2015.
But Detective Inspector Murton said police had not seen evidence of meth becoming easier to get and pricing of drugs fluctuated.
On the other hand, the study found cannabis was becoming harder to obtain and more expensive. The mean price of an ounce increased from $316 in 2012 to $343 last year. The study said successful police cannabis eradication operations could be a factor.
"Police in Canterbury actively target cannabis growers, dealers and supplies," Murton said.
"A dedicated offender prevention team has the focus of preventing the harm caused by drugs and gangs, and their focus is always on this area. Search warrants on drug dealers, growers and manufacturers' premises are conducted regularly."
Fifty-two per cent of those surveyed said they had used cannabis in the past month. That figure had steadily declined since 2013.
When it came to alcohol, those surveyed said they drank less days in a year, with 14 per cent saying they felt dependent on it.
Ecstasy use declined in Christchurch, dropping from 29 per cent in 2011 to 12 per cent last year, while cocaine and illicit opioid use remained low.
Murton said the use of psychoactive substances was a "real concern".
"We see first-hand the harm these products can cause to users and the people around them. Such illicit drugs have a detrimental and negative impact on our communities and we are focused on preventing that."
How quickly those interviewed could buy drugs in Christchurch in 2016:
•Methamphetamine: One hour - 30 per cent; less than 20min - 37 per cent.
•Cannabis: One hour - 23 per cent; less than 20min - 55 per cent.
•Ecstasy: One hour - 39 per cent; less than 20min - 7 per cent.
•Synthetic cannabinoids: One hour - 24 per cent, less than 20min - 66 per cent.
Average cost of drugs in Christchurch in 2016:
•Methamphetamine: Point - $126; gram - $765.
•Cannabis: Tinny - $20; ounce - $343; pound - $4294.
•Ecstasy - One pill - $42.
•Synthetic cannabinoids: Gram - $17.
•If anyone is aware of synthetic cannabis being sold or distributed, police urge them to phone 111 if urgent, their local station, or Crimestoppers anonymously on
0800 555 111.
- star.kiwi
