A poorly regulated grey market is growing online around unapproved peptides, which are being promoted on social media for uses that go from fat loss to anti-ageing.
MedSafe has issued an alert on unapproved peptide products, as it sees increasing imports and sales of the compounds coming into the country.
The Science Media Centre asked experts about the risks of buying peptides online. Feel free to use these comments in your reporting.
Professor Chris Wilkins, Associate Professor Marta Rychert & Dr Robin van der Sanden, SHORE & Whariki Drug Research Team, comment:
What are the biggest health risks of using and self injecting peptides?
“While some peptides can be taken orally or applied topically, the most effective and common form of administration is via self-administered intramuscular or subcutaneous injection to promote more gradual peptide release and sustained effects over time.
“Self-administration of injectable peptides by naïve and inexperienced users carries serious health risks, ranging from injection-related injuries and infections to the transmission of serious diseases like Hepatitis C if needles are reused or shared.
“Additionally, the lack of regulation and mislabelling of products means that there is potential for peptides to be contaminated or to contain an entirely different substance than advertised.”
What does the scientific evidence show about the claimed benefits of popular peptides?
“Unregulated synthetic peptides have surged in popularity in the last few years and can cause serious adverse reactions. Use also carries risk of developing unknown long term health issues.
“At present, there is no data or published research on unregulated peptide use in NZ. Responding to the lack of an evidence base to inform further regulations, the 2026 New Zealand Drug Trends Survey (NZDTS) will collect local data on patterns of performance enhancing drug and peptide use and harms.”
Many of the peptides being bought by NZers online are sold under the label “research use only” or “not for human consumption”. What does this mean?
“Unregulated peptides are commonly promoted by biohackers and fitness influencers for their purported wellness optimization benefits, ranging from anti-aging and tanning to injury recovery, muscle building and weight loss.
“Increasingly, they are also marketed for their cosmetic benefits as skin treatments (e.g., injectable copper peptide GHK-Cu), leading to growing peptide use among new groups such as women.
“However, most have not undergone the clinical safety evaluations needed to be sold as legal medicines. The sale of unapproved peptides is illegal under the Medicines Act in Aotearoa.
“To circumvent these restrictions, these products are marketed as “research chemicals” or “not for human consumption”. This mislabelling and unethical marketing allows the trade to flourish in a legal grey zone between approved and unapproved medicines, potentially putting people at risk of health issues.”
What is the one thing you wish people knew before buying peptides online?
“Unregulated peptides have unknown health consequences. Users should avoid injecting them which comes with additional risk. Buyers can get the contents of drugs checked at drug checking clinics around Aotearoa although this does not guarantee all contaminants will be detected.
“Clean needles and syringes are available via the New Zealand Needle Exchange Programme for those who make the risky decision to inject
peptides. We strongly advise against injecting unregulated chemicals.”
Conflict of interest statement: “The Drug research team have no conflicts of interest to report.”
Professor Clare Wall, Head of the School of Medical Sciences, University of Auckland, comments:
What are peptides, and how different are they from regular supplements or steroids?
“Peptides are small chains of amino acids which are the building blocks for proteins. Your body naturally makes peptides. Peptides act as chemical messages telling cells in your body what to do – examples include peptides involved in blood sugar control, appetite regulation, immune function.
“Consuming dietary supplements containing specific peptides is largely ineffective because we break them down in the digestive tract. There are some very specialised therapeutic peptides that can be taken orally but these have a special formulation which protects them from digestion. Steroids are synthetic versions of hormones such as testosterone.
“Peptides generally do not directly replace hormones. Instead, many stimulate the body to release hormones or activate specific cellular pathways.”
What are the biggest health risks of using and self injecting peptides?
“You may not be getting what the label says! These preparations are not regulated like medicines and independent testing has found incorrect doses, contamination, different compounds.
“Self injection can cause skin infections, abscesses, damage to tissue or blood vessels.
“There are uncertainties about long term safety including effects on growth hormone pathways – including: water retention, joint pain, increased blood sugar, insulin resistance.”
What does the scientific evidence show about the claimed benefits of popular peptides?
“There have been very few long-term robust clinical trials on IV peptides to provide evidence that they are effective and safe. To run large and robust trials requires significant investment that many of the popular IV peptide companies do not have.
“Much of the evidence is from laboratory studies or animal studies, anecdotal reports and very small human studies.
“However, for some of the medical grade peptides such as Semaglutide and liraglutide there is substantial evidence showing benefits of weight loss etc.”
Many of the peptides being bought by NZers online are sold under the label “research use only” or “not for human consumption”. What does this mean?
“This product is being sold for laboratory or research purposes, not as a medicine or dietary supplement intended for people. This can create a regulatory grey area.
“By marketing a product as “research use only,” a seller may attempt to avoid some of the regulatory obligations that would apply if they openly marketed it as a medicine.”
What is the one thing you wish people knew before buying peptides online?
“The biggest question is not “Does this peptide work?” but “How do you know what’s actually in the vial?” And is it safe!?”
Conflict of interest statement: No declaration received.
Professor Peter Shepherd, Faculty of Medical and Health Sciences, University of Auckland, comments:
How do peptides differ from nutritional supplements or steroids?
“Many people seeking to “bulk up” will use nutritional supplements to help this process. Most often this will be in the form of proteins with the rationale being that your body will break these down into the basic building blocks called amino acids and then your body can reuse these to build the very specific new proteins that make up your muscle. The actual composition of amino acids in the protein supplement can also affect outcomes. This works to a certain extent but supplement companies often over hype the effect. Plus some of the supplements have other additives that can cause other problems. It’s a murky area.
“Steroids are small chemicals that we naturally produce and that regulate a wide range of functions in our body. One of these is testosterone which has a range of effects including increasing muscle mass. People have modified the basic structure of testosterone to make new drugs that are way more potent than testosterone itself and the “anabolic steroidal drugs” have some legitimate medical uses but are widely misused by as well by bodybuilders and athletes seeking to increase muscle bulk.
“The term peptide really means a chain of amino acids, and is really just another name for a protein. Our genes in our DNA carries the code for the 20,000+ different peptides our body needs to fulfil all the functions that make us what we are.
“However, in the context of this current debate the term peptides really refers to a small subset of these 20,000, that subset being a group of peptides that we call hormones.
“These peptide hormones control all sorts of processes in our body and drug companies not only produce all sorts of natural peptide hormones (e.g. insulin) but have also figured out how to modify the natural peptide hormones to make them even more effective.
“Wegovy is an example of that. One problem though with peptides is that they are rapidly broken down in our stomach so most peptides have to be injected.”
What are the biggest health risks of using and self injecting peptides?
“Infection is a major concern but also risks that the material in the bottle is not what it says it is.”
What does the scientific evidence actually show about the claimed benefits of popular peptides?
“Some have well documented beneficial effects if used properly, others are far less proven.”
What is the one thing you wish people knew before buying peptides online?
“If the peptide you buy is in fact what it claimed to be you have to really remember that these are things that target the hormonal systems that regulate our body.
“It’s very easy to get the dose of these wrong and the consequences can be really severe.”
Conflict of interest statement: No declaration received.
Jason George, National Harm Reduction Lead, DISC Trust, comments:
What are peptides, and how different are they from regular supplements or steroids?
“Peptides are substances that can influence how the body functions. Some are approved medicines (e.g. Ozempic or Wegovy), while others are not currently approved as medicines and marketed or used for purposes such as muscle growth, injury recovery, weight loss, anti-ageing, or tanning.
“Peptides are very different from both supplements and anabolic steroids.”
What are the biggest health risks of using and self-injecting peptides?
“One of the biggest risks is uncertainty. Many of the peptides being sold have not been adequately tested for safety, effectiveness, quality, or long-term effects. Due to limited regulation, many are not produced in pharmaceutical-grade facilities or subject to rigorous quality assurance processes.
“This means there may be contaminants, variations in purity or strength, or no guarantee the product contains what is claimed.
“Injecting without proper instruction and good injecting practice carries risks, including abscesses, infections, soft tissue damage, and blood-borne virus transmission.
“Poor injecting practices, including sharing needles & syringes or multidose vials, or using previously used needles & syringes to access them can contaminate products and increase the risk of infection and blood-borne virus transmission.
“People considering injecting peptides should seek reliable information about safer injecting techniques and practices from reputable harm reduction and healthcare sources.”
What does the scientific evidence actually show about the claimed benefits of popular peptides?
“While some peptides have recognised medical uses, the evidence for many is limited and the claimed benefits often exceed what has been demonstrated in studies.
“Many people report benefits from using peptides, but personal experiences and anecdotal reports are not the same as scientific evidence. For many products, much of the evidence comes from laboratory or animal studies which don’t always apply to humans.”
Many of the peptides being bought by NZers online are sold under the label “research use only” or “not for human consumption”. What does this mean?
“These labels are intended to indicate that a product is not being sold for human use. Similar labelling has been used with unclassified psychoactive substances being sold as “research chemicals”. While some peptides have legitimate research applications, many of the peptides being sold are clearly intended for human use despite these statements.
“In practice, these statements are often attempts to shift responsibility onto the purchaser and distance the seller from how the product is used. They may also be used to try to avoid regulatory requirements applicable to products intended for human use.”
What is the one thing you wish people knew before buying peptides online?
“Whether a peptide works is only part of the picture. When suppliers provide laboratory reports or certificates of analysis, consumers often can’t verify those documents relate to the specific product they receive.
“Without independent testing, people are relying on trust when it comes to a product’s identity, purity, and quality.”
Conflict of interest statement: “None.”
Dr Rhys Ponton, Faculty of Medical and Health Sciences, Pharmacy, University of Auckland comments:
What are peptides, and how different are they from regular supplements or steroids?
“Peptides are being used by a growing number of people across New Zealand with little understanding of what they are, how they work, or what harm they may cause. Peptides are chains of amino acids — the building blocks of proteins — synthesised to trigger specific biological responses in the body. The desired effects of use range from enhancing performance, or changing the appearance of the body through weight loss, muscle gain or other effects, such as producing a sun-tanned look.
“The peptides used to produce these effects are novel structures that are not used medically. They have not been thoroughly assessed in regard to either their effect or their safety. Furthermore, the number and variety of the products available mean there will be a range of potential benefits and risks attached to their use, which needs assessment on an individual basis.”
What are the biggest health risks of using and self-injecting peptides?
“As unapproved products that are not supplied via the legitimate medical products pathway, they pose a significant risk regardless of whether the product works as intended; each compound will carry its own profile of effects and hazards that cannot be assessed without proper evaluation.
“As products sourced from the Illicit market, there is no quality control. There are risks not only from the purported material (which may be the wrong compound and/or wrong strength), but also from further aspects relating to production including the how well the product has been purified.
“Due to the unregulated manufacturing the products may contain contaminants, by-products or adulterants. The dosing of these drugs additionally raises a significant risk – the data to support the use of these drugs to produce the desired effects without acute or long-term effects simply does not exist. As a harm reduction specialist, I feel it is key to discuss the risks posed by the use of these products.”
“Primary risks relate to routes of consumption – the majority of these products in New Zealand require injection. This raises both risks from the product (on injection) and the injection process. Risks are compounded by injection by people with little or no experience with the injection of drugs, and any information provided by people with no expertise or qualifications to provide such information, leading to dangerous injection practices.”
“Injection site injuries (including damage caused by the product/drug) are commonly the result of the use of inappropriate injecting equipment for the application, e.g., a needle of inappropriate gauge or length for the intended injection site and depth. Injection site infections can result from contaminated injection materials or equipment, or from bacteria or fungi present on the skin that transfer to internal tissues during the injection
process.
“The reuse of multidose vials can lead to contamination, especially if safe sterile use procedures are not followed, and there are additional risks if vials are shared amongst individuals. Bacteriostatic water is limited in its effect in reducing infection and in no way guarantees sterility.
“The sharing of injection equipment carries specific well-understood risks, in particular that of blood-borne virus transmission. The reuse of injection equipment by one individual carries risk: from physical injury caused by blunt needles to bacterial or fungal infections as a result of equipment becoming contaminated by organisms during storage between uses.
“Safe injecting practices are to be encouraged, however consumers of these products may never have injected drugs before and therefore be unfamiliar with practices that have been driven home to consumers of more traditional drugs of misuse over many decades. These were initially developed by newly created needle exchange services in response to the emergence of HIV in the 1980s and more recently to tackle hepatitis C.
“Safe injection practices are essential, and include:
- Using new, clean equipment for each use – do not reuse equipment, even for use by the same person.
- Using the right equipment for the type of injection, for example, subcutaneous injection vs intramuscular injections, which require very different needle sizes and lengths and which dictate different injection volumes.
- Never sharing equipment between individuals; Importantly with regard to these products, it means not sharing multidose drug containers, even if using different injecting equipment.
- If using with or around other people, not injecting in close proximity, i.e., where there is the risk that equipment or materials could get muddled up.
- Ensure the safe disposal of used equipment (‘sharps’).”
What is the one thing you wish people knew before buying peptides online?
“Peptides are commonly sold and obtained as ‘lyophilised’ (freeze-dried) powder which requires reconstitution before injection. This is a particular point of risk as over- or under- dilution will lead to a product that is stronger or weaker than expected or intended, leading to the dose of the product injected being higher or lower than expected.
“Peptides are fragile molecules and require careful storage to reduce degradation. As products sourced from a market without careful temperature regulation (a ‘cold chain’), they may have degraded by the time they have been received. Once diluted, they will degrade more rapidly and careful storage is vital.”
Conflict of interest statement: No declaration received.