At some point in the last year, testing black-market peptides stopped being an occasional favour and became a routine job. That is the quiet takeaway from a joint investigation by the ABC, the University of Queensland and harm reduction group PED Test Australia, which sent counterfeit retatrutide vials to a Melbourne laboratory and published what came back.
The short version: of 18 samples of black-market retatrutide tested by the lab so far this year, exactly one matched its label claim. Around 30 per cent came in at higher concentrations than labelled. Around 30 per cent came in lower. One vial contained no retatrutide at all.
If you have been following our coverage of the retatrutide grey market or the Victoria liver toxicity cases, none of this will surprise you. But the direction of the dosing errors might.
The lab that saw the market change
Grace Hamann is an analytical chemist at Leeder Analytical in Melbourne. This time last year she had never heard of black-market peptides. Now, she told the ABC, about half her job is testing them.
“October 2025, we started to get almost daily requests for testing,” she said.
That spike tracks the social media peptide boom exactly. As unapproved compounds gained visibility online, demand for purity and dose testing from consumers and the wellness industry grew fast enough that the lab upskilled specifically to test these substances.
The investigation centred on three vials of counterfeit retatrutide obtained from black-market users at the ABC’s request, with testing paid for by UQ’s School of Public Health and PED Test Australia. The results were unexpected in a specific way: while one vial contained less retatrutide than its label suggested, two contained much higher concentrations.
That runs counter to the usual assumptions about the black market. The intuitive model is “vendor cuts the product to save money.” The data does not support that being the whole story.
Overdosing is the surprise
Hamann was blunt about the pattern: “You would expect if you’re buying an unregulated product that they’d want to cut costs [and include less of the drug]. But the fact that we’ve had almost equal amount to be over 100 per cent than under 100 per cent, surprises me.”
UQ peptide researcher Tim Piatkowski said the results contradicted what he had seen in steroid testing, where underdosing is by far the dominant problem. “I definitely didn’t expect that level of overdosing,” he said.
The findings were written up for the journal Drug and Alcohol Review. The paper’s framing matters: “Although media attention has often focused on counterfeit or adulterated products, these findings suggest that inaccurate dosing alone may represent an important source of risk.”
That is the key sentence. The community has spent a lot of time worrying about outright fakes, contaminated product and the question of whether a vial contains the right compound at all. What this data says is that even when the compound is right, the dose can be dangerously wrong - in both directions.
This is not an abstract concern. Earlier in the investigation, ABC testing found a black-market retatrutide vial labelled “10 mg” that actually contained 19 mg - nearly double the labelled strength - at 16.6 per cent purity, with the remainder likely filler material such as mannitol. Melbourne gastroenterologist Dr Darcy Holt described the overdose risk as “enormous,” and told the ABC about a patient who took a high dose of retatrutide and developed a critical case of secretory diarrhoea that could have been life-threatening from dehydration and electrolyte disturbance. “He could have become so dehydrated with such severe electrolyte abnormalities that he could have died,” Holt said.
The bigger Australian picture
The timing matters. Australian regulators and health bodies have spent 2026 escalating their response to the peptide boom, and the ABC’s own undercover ordering investigation from August showed how easy it is to buy unapproved compounds through social media. The TGA enforcement push has now run through the year, with seizures and compliance actions.
Here is the number that puts the problem in scale: the Australian poisons hotline received more calls related to unapproved peptides in the first six months of 2026 than in the two previous years combined, according to data reported by the AFR on 10 August. That is a leading indicator, and it points the same direction as the lab numbers - real people are taking real doses of product that nobody has verified.
What the Research Says
The evidence from the ABC/UQ investigation, in brief:
- Leeder Analytical tested 18 samples of black-market retatrutide in 2026; only one matched its label claim.
- Roughly 30% of samples came in over the labelled concentration, roughly 30% under, and one vial contained no detectable retatrutide.
- Three vials tested for the ABC: one underdosed, two overdosed relative to label.
- One vial labelled 10mg contained 19mg of retatrutide at 16.6% purity, rest likely mannitol filler.
- A Melbourne gastroenterologist reported a high-dose retatrutide case causing critical secretory diarrhoea with potentially life-threatening dehydration and electrolyte abnormalities.
- The results were submitted to the journal Drug and Alcohol Review, which concluded inaccurate dosing alone may represent an important source of risk.
The limits of the data are worth stating plainly. Eighteen samples is a small, convenience-based sample - people who chose to test, or whose vials were captured by journalists - not a randomised survey of the market. Leeder’s broader testing volume suggests the pattern is not a blip, but nobody should treat this as a precise market-wide failure rate. It is evidence of a serious problem, not a precise measure of it.
What this means for the community
Two things, neither of which is comfortable.
First, the “just buy from a trusted vendor” heuristic is weaker than people think. If the same product stream produces both underdosed and overdosed vials, then a vendor’s reputation is not a reliable proxy for what is in any single vial. The only real protection is testing the actual product you have, which is exactly why harm reduction groups like PED Test Australia exist, and why paying for third-party analysis is the responsible move for anyone doing serious research with unapproved compounds.
Second, the overdose finding changes the risk conversation. The community has talked a lot about contamination and underdosing. This data says the realistic failure modes include getting substantially more compound than intended. For a powerful compound like retatrutide, which is still in Phase 3 trials and unapproved anywhere, the difference between a research dose and a harmful dose can be smaller than the label error this lab keeps finding.
As always, Grey Highway is an education and research community. We do not sell or supply compounds, and we are not telling anyone what to do. What we can do is keep surfacing the data that makes the grey market legible, and let people make informed decisions with their eyes open. The dosing data from Leeder, UQ and the ABC is a significant piece of that picture.
If you want to discuss the findings with other researchers, the Grey Highway Telegram community is where the conversation lives.
Disclaimer: This article is for educational and informational purposes only. It does not constitute medical advice, therapeutic recommendations, or endorsements of any compound. Grey Highway is a research-education community. We do not sell, supply, or promote the use of research compounds. Always consult a qualified healthcare professional regarding health decisions. For Australian regulatory information, visit the TGA website.
Sources: ABC News, “We tested counterfeit peptides off the black market. Here are the results”, 27 August 2026 (syndicated at MSN: https://www.msn.com/en-au/money/general/new-testing-of-black-market-peptides-reveals-dangerous-dosing-levels/ar-AA2b3zJU). ABC News, “Vial of unapproved peptide retatrutide had double the strength indicated on label”, June 2026: https://www.abc.net.au/news/2026-06-27/double-strength-retatrutide-peptide-sparks-warning/106844372. Piatkowski et al., findings reported to Drug and Alcohol Review (2026). Australian Financial Review, “Peptide craze leads to surge in calls to poison hotline”, 10 August 2026: https://www.afr.com/life-and-luxury/health-and-wellness/peptide-craze-leads-to-surge-in-poison-hotline-calls-20260810-p60mx8.