More than half of MDMA being checked at festivals this year is actually a more dangerous drug known as bath salts.
Under a new law, testing organisations can now legally check people's drugs, and it's revealing an alarming increase in other substances.
"This season is very different to previous years, we are seeing a hell of a lot of cathinones," Know Your Stuff deputy manager Dr Jez Weston says.
"These are a stimulant - not as much fun as MDMA and a lot more risky."
It is a risk that has Rhythm and Alps on guard.
"We're quite concerned at the level of cathinones being sold as MDMA," founder Alex Turnbull says.
"We encourage people not to purchase drugs and keep safe here at the festival."
But the new law apparently wasn't passed in time for the larger festivals to get drug testing organisations on-site, which is something festival-goers are keen to see.
"I wish they had a testing site here at this festival," one tells Newshub.
"Don't touch it, it's not worth it, and if you do get it tested," another says.
Last month, Wellington police seized 20kg of a substance called eutylone, which can cause seizures, anxiety, and psychosis. It's a type of cathinone often sold as MDMA because it looks similar.
"Your drug dealer is not your friend, they are trying to make money and are trying to fool you into thinking you have something stronger or better - they're basically giving you rubbish," Wellington emergency doctor and toxicologist Paul Quigley says.
St John paramedics have been flat out at festivals this week - dealing with sunburn and intoxication - as well as people showing symptoms of recreational drug use. The organisation is calling for widespread drug testing.
Quigley also wants some drugs, such as MDMA, to be regulated.
"You have no idea what you're getting or how strong it is," he says.
"A good old Kiwi will take a whole capsule without realising it's six to eight doses."
It's believed the surge of bath salts in New Zealand is linked to Europe's COVID-19 lockdowns.
"Cathinones are produced in Southeast Asia, and Southeast Asia has done a much better job than Europe of dealing with COVID," Weston says.
Know Your Stuff says it's dealing with this big problem by talking to the Government about scaling up festival drug testing.