08/26/2026
“Third-party tested.” “99% pure.” “Sterile.”
Those words sound reassuring when you’re buying a peptide. But there’s a limit to that reassurance.
The bigger question should be: Tested for WHAT, exactly?
With the explosion in peptide use, more people are turning to inexpensive “research-grade” peptides purchased online—often assuming that a Certificate of Analysis means the product has been thoroughly evaluated for everything that could make it unsafe to inject.
News flash: It doesn’t.
A peptide can be certified as sterile and still contain bacterial endotoxin.
That’s because purity testing, sterility testing, and endotoxin testing are three different things.
Endotoxin testing is commonly absent from standard research-peptide COAs. Typical research-use COAs focus on HPLC purity and mass-spectrometry identity; endotoxin testing is a separate assay and is often not included. You would need to see lot-specific LAL/endotoxin testing, sometimes with numerical EU/mL or EU/mg results. If it’s not reported, chances are it’s not being done.
In this video, I explain where endotoxins come from, why they can remain even after bacteria have been eliminated, what we know—and importantly, what we don’t know—about long-term, low-level exposure, and why sourcing matters when something is going directly into your body.
I prescribe peptides routinely and I’m excited about where peptide medicine is going. But I’m equally passionate about using these therapies thoughtfully and safely.
If you use peptides—or know someone who does—I think this is worth watching.
Were you aware that “sterile” does not necessarily mean “endotoxin-free”?
Tell me what you think in the comments, and please share this with someone who is using or considering peptides.
For more educational and informational content like this, regarding peptides, hormone optimization, sexual wellness, and topics in aesthetic medicine, consider following my new YouTube channel. I will place the link in the comments.
Lisa Vuich, MD
