Security checks at one of the country's busiest New Year celebrations uncovered a mystery drug containing pesticides and other potentially dangerous substances.
The Rhythm and Vines music festival in Gisborne confiscated the drugs and alerted health authorities.
Newshub understands the pills look like MDMA or Ecstasy and are purple.
- Rhythm and Vines organisers stop bad drugs entering festival
- Festival drug testing finds more new psychoactive substances than ever
- Greens want drug-testing legal by summer festival season
"We have the ability to be able to actually look at contents of the drugs that we seize," Inspector Andrew Sloan told Newshub.
"You don't know what you're taking so be aware of this sort of stuff and be safe."
Analysis of the substance found they contained dangerous compounds like pesticides, paints and antibiotics.
"We're really against people over indulging and taking drugs but unfortunately people do do that, and we just provide a safe space for them to come and be looked after," St John Ambulance's Shane Clapperton told Newshub.
While the bad batch of pills didn't make it into the festival, there was still plenty of other contraband trying to get through the gates.
Drugs and alcohol-related emergencies kept St John Ambulance paramedics busy. Leading up to midnight, they saw up to 50 partygoers an hour.
"We are seeing some people who have overindulged and we're just looking after them and trying to get them patched up and back out there, but some of them have had their nights spoiled by overindulging," Mr Clapperton said.
But for the vast majority, Monday night topped off three days of summer celebrations.