For anything bought outside the regulated supply chain, the contents of the vial are an open question. Independent testing gives a sense of how open.
What testing has found
In 2026 an analytical laboratory tested 18 samples of a single compound obtained from the grey market. One matched its labelled concentration. Roughly 30% were stronger than labelled, roughly 30% weaker, and one vial contained none of the compound at all.
The same work found that the peptide typically accounted for about 10% of vial contents. What made up the remaining 90% was not established.
Mislabelling, not just inaccuracy
In a July 2026 case, vials sold in New York retail stores as one compound were found on testing to contain a different drug entirely. The certificate of analysis supplied with them was confirmed as fake by the laboratory it named.
What a certificate of analysis proves
- Identity: whether the compound present is what the label says.
- Purity: what proportion of the peptide content is the intended compound.
- Usually not quantity per vial, which is what determines a dose.
- Usually not sterility or endotoxins, which is what matters for anything injected.
- Nothing at all, if it is fabricated or if it refers to a different batch.
A certificate hosted only on a seller’s own website, with no way to verify it with the issuing laboratory, is an assertion rather than evidence. Independent verification spending reportedly fell about 88% per buyer as reliance on vendor-supplied certificates grew.
Why unpredictable strength is the central risk
For any compound where effects scale with dose, a vial containing 30% more than labelled converts a chosen dose into a different one. Where a compound is dosed in milligrams and escalated deliberately in trials for tolerability, that variation defeats the purpose of escalating at all.
This is the most likely explanation for why self-reported experiences with online peptides often fail to match the pattern seen in clinical trials of the same compound.