ABC Australia-led research has found that black market peptides sold online often contain incorrect and unsafe dosing levels. Testing showed that many products labelled as weight-loss peptides do not match what is actually inside the vials.
Some samples contained much higher amounts of the active substance than stated, while others contained less or none at all.
How the investigation was done
The investigation was carried out by ABC Australia in partnership with the University of Queensland and laboratory Leeder Analytical.
Researchers tested counterfeit peptides, mainly products labelled as retatrutide, a weight-loss drug still in clinical trials and not approved for human use.
Three vials were tested directly for the study, and wider lab data from 18 samples tested in 2026 was also reviewed.
What the tests showed
From the 18 samples tested:
- Only 1 matched the label dose
- About 30% contained higher-than-stated levels
- About 30% contained lower-than-stated levels
- 1 sample contained no detectable peptide
In the three-vial test, two samples had higher concentrations than labelled, while one had a lower amount.
Researchers said the results show large inconsistency in how these products are made and sold.
Expert reaction
University of Queensland researcher Tim Piatkowski said the level of overdosing was unexpected and different from past testing of illegal steroids, which more often show underdosing.
Medical experts warned that incorrect dosing increases health risks.
Liver transplant specialist Dr Marie Sinclair said patients using these products may assume testing makes them safe, but this is not true. She said unregulated vials can still contain unknown substances and contaminants.
Safety warnings
Australia’s Therapeutic Goods Administration (TGA) said black market peptides are not approved medicines and have not been tested for safety or quality.
Officials warned that:
- These products are not clinically tested
- Manufacturing is not regulated
- Small changes in dose can cause serious health risks
The TGA also warned that testing for one ingredient does not confirm the product is safe or pure.
Wider concern
Authorities in Australia have seized and destroyed large quantities of illegal peptides this year.
Researchers say the main concern is not only incorrect dosing, but also unknown chemicals inside these products. This makes their use unpredictable and potentially dangerous.