Fake ecstasy tablets that render users angry and aggressive have landed at least eight young Aucklanders in hospital needing sedation.
Middlemore Hospital in Manukau has reported half a dozen cases of drug-takers seeking emergency treatment last week after taking pills known as "red rockets" that they believed were ecstasy.
A further two people were treated on Friday.
While packaged as MDMA-based ecstasy pills, the tablets trigger behaviour similar to methamphetamine intoxication from those who take them, hospital spokeswoman Lauren Young said on Monday.
"They're coming in very aggressive, agitated and certainly wound up," she said.
"It's more like methamphetamine, which is prolific in South Auckland."
Some users suffered violent seizures and hallucinations that shocked staff, and all required sedating until they were well enough to leave.
Ecstasy tablets are made with MDMA and are known to make users feel euphoric, but sometimes the drug is cut with other chemicals and may contain no MDMA at all.
Police and drug specialists fear this latest batch of pills may be available in large quantities in Auckland over coming weeks and have warned potential buyers to be aware they may not be getting what they're paying for.
"They might get a bunch of chemicals that are entirely different and could include methamphetamine," Massey University drugs researcher Dr Chris Wilkins told the New Zealand Herald.
"Methamphetamine has got a really bad reputation at the moment as quite a harmful drug.
"One way to sell methamphetamine is to call it ecstasy and sell it as a powder."