Lab Finds Wide Dosing Variability in Counterfeit Weight-Loss Peptide Retatrutide

Amid a boom in illicit peptide sales online, Leeder Analytical expanded its capabilities to test unapproved substances, reporting that demand for such analysis has grown exponentially. Recent testing of three black-market retatrutide vials, commissioned by the University of Queensland and PED Test Australia, found two with concentrations markedly exceeding label specifications and one with a lower amount. The lab’s 2026 data show that out of 18 retatrutide samples, only a single vial matched its label claim, while about 30% were overdosed, another 30% underdosed, and one contained no detectable peptide.

Experts note that inaccurate dosing poses a serious health hazard, especially since the products are untested for safety and may contain unknown contaminants. The Therapeutic Goods Administration stresses that even correct peptide identification does not guarantee safety, citing risks such as endotoxins and heavy metals. Eli Lilly, the patent holder of retatrutide, warns consumers that any online version is unapproved and unsafe.