Methamphetamine is becoming harder to get, more expensive and is poorer quality due to travel restrictions caused by Covid-19.
The change has prompted the NZ Drug Foundation to warn users that the substance they are currently getting their hands on may be a different strength or have different ingredients substituted so could be dangerous and result in hospitalisation.
The National Drug Intelligence Bureau said the international border closures had disrupted international methamphetamine supply chains and made it harder for the drug to get into New Zealand from its main sources Southeast Asia and North America.
• Meth bust: Charges after Customs finds methamphetamine in Auckland Airport traveller's suitcase
• Methamphetamine still the drug of choice in New Zealand according to new police data from national wastewater testing
• Methamphetamine user tell how drugs 'completely destroyed my life'
• Methamphetamine prices drop to record lows despite big seizures
The domestic travel restrictions placed on New Zealand during alert level 3 and 4 had also made it difficult for both the product and precursors to travel around the country.
The Herald has been told by a source that methamphetamine has been difficult to access for the past few weeks.
"It's impossible to obtain anywhere ... and if it does pop up, you're having to pay high prices for your fix. It's ridiculous."
People were also being sold salts, MSM and other substances that looked like methamphetamine.
Drug bureau manager Detective Inspector Blair Macdonald said the majority of the drugs arrived in New Zealand via Auckland. These drugs were then typically transported across the country and into the South Island on either regional flights or in vehicles using the Cook Strait ferries.
Macdonald said there was anecdotal evidence the price and availability of meth varied according to the region. In harder-to-reach areas such the South Island the price was higher.
However, he believed the disruption to supplies would be short-term because organised crime groups had resilient drug supply streams and exploited a range of importation methods to ensure a steady supply of illicit substances.
Ben Virks Ang, deputy executive director in charge of programmes at the Drug Foundation, said feedback from treatment services was that some of the people they were supporting were finding it more challenging to get the same quality substance or that the price had increased.
"I think there's still a lot out there that they could say is meth if they were wanting it, but harder to trust that it actually is methamphetamine."
Virks Ang was concerned that because a large number of people had stopped using the substance during lockdown - their tolerance may have dropped so they may not be able to handle the same amount of the substance or could be taking a different type of substance so were at a high risk of overdosing.
People who were dependent on a substance were also less able to suddenly reduce or stop their use so were more likely to try different substances or accept a substance even thought they knew it might not be the real product.
"And all of that puts people at higher risk of needing medical help because they've taken too much and overdosing."
Massey University's Shore & Whāriki Research Centre is still in the process of analysing the data collected during the lockdown period, but research from last year showed the median price for a gram of methamphetamine had dropped from $538 in 2017/2018 to $500 in 2018/2019.
Auckland, Waikato and Wellington are the cheapest places to buy it.
At the time, associate professor Chris Wilkins said the lower prices reflected the regions' proximity to international smuggling routes, for example airports, seaports and isolated coastlines, and the concentration of domestic meth manufacture in those regions.
Data provided by Customs showed that so far this year the amount of illicit drugs, including meth, seized at the borders is less compared with the same time over previous years, but this was expected to rebound once trade increased later this year.
A Customs spokesperson said it had continued its efforts to risk assess all passengers, cargo, mail and craft during the Covid crisis.