Six sellers of a coffee powder marketed as a weight loss product have been told to close up shop or face prosecution after the brew was found to contain potentially dangerous levels of phenethylamine.
MedSafe is warning consumers to ditch any supplies of Elevacity Elevate Smart Coffee (version 3) powder, and get medical advice if feeling unwell.
Compliance manager Derek Fitzgerald told Checkpoint there were "fairly soft therapeutic claims" being made about the product.
"The control drug that's in there occurs in very small amounts in natural coffee, but these products have been fortified if you like.
"It's clear that they are using those therapeutic claims to market the product over and above ordinary coffee."
Fitzgerald said the class-C controlled drug contained in the powder could cause reactions such as agitation, increased heart rate and blood pressure, and psychological effects.
He said they had officially warned six distributors in New Zealand, who were getting the product shipped to them from overseas.
"As far as we are aware, at the present time, they have been complying with that and have shut down that particular part of their business."
While items that are shipped which appear to be medicines - like tablets or ointments - do get scrutinised at the border, others could slip by.
"As they come in the post and it looks like a pot of coffee, it could go through. So we recommend that people do not buy this and that applies to a whole load of therapeutic-like or therapeutic products that might be offered online and coming from overseas," Fitzgerald said.
"We probably detect around about 1000-1200 packages a year that are coming through that contain maybe prescription medicines for instance, or control drugs.
"They are stopped at the border and the person they are consigned to has to have a good excuse, for instance, a prescription from their doctor ... there is a mechanism there that will stop some products from entering the country that's for sure."
It is the second time this week the watchdog has issued a serious warning about products masquerading as medicines; making unsubstantiated therapeutic claims - with no proof with the risk of significant side effects.
MedSafe dropped charges against the makers of Arthrem in favour of a deal to stop making and selling the product, for which they had received warnings on since 2016.
"What we have in the background is an upgrade to the Medicines Act, which will provide much better mechanisms to take action, other than prosecuting through the courts," Fitzgerald said.
However, he said most organisations once warned about a product, would stop selling it.
"Quite a lot in that particular area don't realise that they are breaking the law some, some do, and they will stop their advertising and supply. So there are only very few that really go through to the process where we find that we have to prosecute them."