Latest drug checking data shows 91% of substances matched expectations — but risky substitutes and toxic additives are still being found.

KnowYourStuffNZ checked a total of 3,943 samples at 165 events in the 2024-25 drug checking season, which runs from April – March.

Most notably, 91% of drug samples turned out to be what people thought they were. This is the highest portion of samples to date, up from 2020/21’s low of 69%, said a KnowYourStuffNZ statement.

Of the 9% of drugs with question marks, 2% had additional substances such as fillers or other psychoactives, and 5% were something else entirely, 2% were inconclusive.

“While 91% may seem like a great result, it should still come as a concern that 9% of all samples were something different from what they were purchased as,” KnowYourStuffNZ general manager Casey Spearing said.

“These can range from relatively harmless to very high-risk. While substitution is slightly down overall, many of the substances that are being substituted or added are much higher-risk than we have seen in previous years.”

Many substances of concern were detected through drug checking services last year.

Nitazenes are a relatively new class of potent synthetic opioids, similar to fentanyl.

They were first detected in New Zealand in 2022, and have since been found at drug checking clinics, often sold as counterfeit medicines such as benzodiazepines.

Other notable detections included a ketamine analogue ‘CanKet’ first discovered in Australia in 2022, a new type of cathinone, and in several cases, toxic chemicals used in manufacturing.

Cathinones, says Spearin, have been sold as MDMA for well over a decade now, but continue to pop up in new forms.

“This year we saw the emergence of n-isopropylbutylone.

“It’s a constant sprint for drug checking organisations to keep up with the new substances on the market and ensure that we’re giving people the best harm reduction advice we can.”

“We continually see this pattern where the manufacture of these substances overseas is banned by legislators – and the manufacturers quickly design and pump out new substances to skirt these regulations.

“This means that, here in Aotearoa, people are consuming these drugs with no knowledge of their identity, effects, dosage, or immediate or long-term risks to their health.”

Drug checking is a vital harm reduction tool to help people make informed decisions about their drug use.

“Our data shows that half of people choose not to take a substance when it’s not what they expected — and nearly all say they wouldn’t take it if it’s known to be especially risky,” deputy manager Jez Weston said.

“Additionally, nearly all clients report changing their behaviour to safer practices after the harm reduction conversation.”

New Zealand is world-leading for its support of drug checking services, being the only country which has specific legislation to offer legal protection to people bringing their drugs in to get checked.

Despite this, there’s a long way to go.

“We know that less than 1% of the drugs consumed in Aotearoa are presented to a drug checking clinic,” said Spearin.

“Our hope for 2025 and beyond is that we can continue to expand our reach, particularly in rural areas, and offer more opportunities for people and communities to have these vital conversations about drug safety.”

Read the full report here.