A medical examination has shown the substance that hospitalised 13 people in Christchurch was not MDMA, as they thought, but another drug three times as potent.
Police issued a warning about N-Ethylpentylone on Tuesday, advising people of the potential dangers of the drug.
This comes after 13 people, including a 15-year-old, were admitted to the Christchurch Hospital Emergency Department at the end of February with symptoms and side effects associated with having taken an MDMA-containing substance.
It was then assumed the people had taken a dodgy batch of ecstasy.
The issue for the public is that a dose of MDMA/ecstasy is generally 100mg - however, to get the same effect, only 30mg of N-Ethylpentylone is required,
"Hence, if N-Ethylpentylone is mistaken for MDMA/ecstasy, the user will be taking three times the 'prescribed' dosage, posing a danger to themselves."
Police say accidental overdoses of the drug have killed people overseas.
"The importers, manufacturers and dealers of these types of drugs, in the form of MDMA, synthetics and so called 'party pills' have no scruples about what they put into them, most of which are simply chemicals in varying doses," Det Insp Murton says.
"Dealers have no idea of the potency of the drugs they are supplying, nor what is contained within them - or simply do not care."
Canterbury DHB Emergency Medicine Specialist Paul Gee says duty doctors at the hospital were very astute in picking up that the behaviour of the patients was not consistent with usual MDMA side effects.