‘Walking the tightrope’: Experts worried about the rise of peptides

Peptides have been growing in popularity recently, with online sellers promising a wide range of benefits. What they don’t mention, of course, is the equally wide range of potential side-effects and general complications which can arise from their use. That job instead falls on the experts and academics, with regulatory body Medsafe issuing a consumer advisory about them last month. Speaking to rova, the Ministry of Health’s Dr Anna Skinner described the explosion in packages containing peptides which have been caught coming into New Zealand:

“There has been an increasing number of intercepts of these peptides over the last year, and particularly in the first part of this year. In the whole of 2025, 370 packages were intercepted at the border. Between January and April this year, just over 200 packages have been, which is a substantial increase. Prior to 2025, there were under 100 intercepts a year. 

There is absolutely no quality control on these, there's no certification of the factory in which they’re produced. We don't know if there's bacteria, heavy metals or any other contaminants. Also, because these are unregulated medicines that have not been approved, they haven’t been through clinical trials to prove their safety or efficacy.”

Dr Skinner also broke down how some sellers are trying to use misleading labelling to make it appear as though their operations are all above-board:

“There is some confusion out there about having things labeled as being for research purposes only, which gets around the fact that it is illegal to import unapproved prescription medicines without a prescription. It actually doesn't make any difference. The disclaimer is not useful and doesn't make the sale lawful, but I think it's been presented on some websites as a way to make it seem lawful.” 

For more about why it might not be a good idea to inject yourself with mystery chemicals from the internet, rova also spoke to Professor Peter Shepherd from the University of Auckland:

“Some of these peptides are not as pure as people think, and have byproducts in them that will give unexpected effects, or may not even be sterile in some cases, which could potentially lead to infections. Even more worrying is whether you’re getting the right dose of some of these things. If it's too low then you're not going to get an effect. If it's too high, you can have dangerous side-effects. So you're walking the tightrope of getting the exact right amount of the drug.

There are many different types of peptides that have a wide range of effects, and supposed effects. Some of them have a lot of evidence based in scientific literature and are used medically, and can be beneficial if used under the correct supervision. Some of the peptides that are being sold however have almost no real evidence to support what the claims of their effects are. But there are many different types of peptides, which is one of the really confusing things, and people are just saying, "Look, they’re all peptides," and then they're going for them. But it could be a really really dangerous thing for people to do.”

Asked what can be done about this, Professor Shepherd felt the most important thing was education, rather than solely relying on new laws:

“Legislating against them can be done, and it is being attempted to be done, but these things just keep popping up in different forms. They’re often coming from overseas so they're very hard to regulate, and it’s not always possible to intercept them at the border. What we really need to do is make people aware that, just because social media says something's good, it doesn't mean that this is the case. These things are really affecting the way your body works and could have really really damaging consequences on you. So be super careful and check, and only use these things under proper medical advice and guidance.”