What's in the vial
No regulator checks research peptides before they're sold. The people who have tested them afterward keep finding problems.
Last reviewed . About this date
Lab tests of peptides bought online
Semaglutide ordered without a prescription
In a 2024 study, researchers ordered semaglutide from six websites that sold it without a prescription (Ashraf et al., 2024a). Three sellers never delivered and asked for another $650 to $1,200 in fake customs fees instead. The three vials that did arrive claimed 99% purity and tested at 7.7% to 14.37%. They held 28.56% to 38.69% more semaglutide than their labels said, and every one carried endotoxin (Ashraf et al., 2024b). Both papers report the same purchases.
Pooled results across research peptides
An April 2026 preprint, which hasn’t been peer-reviewed, analyzed 6,441 test results from Finnrick’s public dataset. The results covered 14 peptides, retatrutide, tirzepatide, BPC-157, and TB-500 among them (Mendias & Awan, 2026). Depending on which quality standard the authors applied, 41.6% to 71.1% of samples failed. Of the 243 samples with endotoxin data, 15% had a measurable amount.
Finnrick collects samples from vendors and sends them to outside labs, mostly for HPLC testing, and endotoxin testing is optional (Finnrick, 2026). As of September 2026, its retatrutide page listed results from 256 sellers, going back to December 2024 (Finnrick, 2026). Read these numbers with their limits in mind: nobody has peer-reviewed the dataset, and a good Finnrick rating doesn’t make a seller legal or its vials safe.
Endotoxin
In February 2026, Finnrick reported on 140 endotoxin tests. Nearly 63% found none, 29% found traces below the level the test can measure precisely, and nearly 8% came in above that level (Finnrick, 2026). That level is a limit of the test, not a safety limit.
Lilly’s warnings
Lilly warns that illicit retatrutide “may contain harmful contaminants, impurities, or the wrong ingredients entirely” (Lilly, 2026). We couldn’t find retatrutide test results published by Lilly. In August 2026, the company said it had filed six lawsuits against sellers and reported more than 14,000 websites, ads, and social media posts selling illegal retatrutide in over 100 countries (Lilly, 2026).
Retatrutide’s status
No regulator anywhere has approved a medicine containing retatrutide (Lilly, 2026). The only legal way to get it is inside Lilly’s clinical trials (Lilly, 2026), and Lilly plans to file with the FDA in early 2027 (Lilly, 2026). Any reta you buy online came from someone other than Lilly.
Regulators on “research use only”
- FDA warns about semaglutide, tirzepatide, and retatrutide “falsely labeled ‘for research purposes’ or ‘not for human consumption’” (FDA, 2026).
- FDA warning letters sent to research-use-only sellers in 2026 cite the sellers’ own marketing as proof their products were drugs meant for people (FDA, 2026) (FDA, 2026) (FDA, 2026).
- Health Canada told Canadians in April 2026 to think twice before injecting peptides bought online. It named BPC-157, TB-500, and retatrutide, and said a research-use-only label “does not make these products legal” (Health Canada, 2026).
- Australia’s TGA put unapproved peptide suppliers on notice in July 2026, warning that the products may contain the wrong ingredients or fail sterility (TGA, 2026).
- The UK’s MHRA seized more than 2,000 unlicensed retatrutide and tirzepatide pens at an illegal factory in October 2025 (MHRA, 2025).
Classic research peptides
In its review of BPC-157 as an ingredient, FDA said the peptide “may pose risk for immunogenicity” and raised problems with peptide-related impurities (FDA, 2026). FDA now lists BPC-157 and TB-500 as previously on its list of substances with significant safety risks, because the groups that nominated them withdrew. FDA didn’t clear either peptide.
The paperwork problem
In a May 2026 article for The Conversation, a McMaster University professor wrote that the “third-party” labs behind vendor COAs are often the vendors themselves (Phillips, 2026). A 2025 editorial in the Annals of Pharmacotherapy looked at 38 websites selling semaglutide and tirzepatide “for research purposes.” Only 4 asked buyers to tick a box, none checked age, and 17 then showed the authors targeted social media ads (Belcourt et al., 2025).
Next steps
The vendor checklist walks through the checks that catch fake companies and fake paperwork. If a vial looks wrong or you feel unwell, go to the bad batch page.
Sources for this page
- Safety and Risk Assessment of No-Prescription Online Semaglutide Purchases
Only 3 of 6 semaglutide orders arrived, scam sellers sought $650 to $1,200 more, and vials tested 7% to 14% pure vs 99% claimed with 29% to 39% extra drug; one had elevated endotoxin (8.95 EU/mg).
- Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study
Of 317 online pharmacy links, 134 led to 59 illegal sites; test vials were 7.7% to 14.37% pure, held 28.56% to 38.69% more semaglutide than labeled, and all had endotoxin.
- Evaluation of Research Grade Peptides Marketed Directly to Consumers Reveals Extensive Variability in Purity and Measured Abundance Not peer-reviewed
A preprint of 6,441 Finnrick-tested samples across 14 peptides finds 41.6% to 71.1% failed basic quality criteria, and 15% of 243 endotoxin-tested samples had measurable endotoxin.
- Methodology
Finnrick says it sources samples from vendors and sends them to third-party labs, requests HPLC as the primary method, and does not require endotoxin testing.
- Retatrutide Safety Testing Results & Vendor Ratings Not peer-reviewed
Finnrick lists 3,694 retatrutide tests from 256 vendors, dated Dec 17, 2024 to Aug 26, 2026; its public test history table shows only 200 of them.
- Why Endotoxin Testing Matters for Peptides Not peer-reviewed
Of 140 Finnrick endotoxin tests, nearly 63% found none, 29% found traces below the limit of quantification, and nearly 8% found amounts above that limit.
- Identify Real Lilly Medicine
Lilly warns that illicit retatrutide, often sold under a "research use only" pretext, may contain harmful contaminants, impurities, or the wrong ingredients entirely.
- Lilly calls on online platforms, payment companies and regulators to shut down the illegal retatrutide black market
Lilly says no retatrutide medicine is approved anywhere; it filed six new lawsuits, referred 200+ parties to authorities, and reported 14,000+ sites, ads, posts and listings in 100+ countries.
- What to know about retatrutide: An investigational triple hormone receptor agonist
Lilly states that no regulatory agency has approved retatrutide and that it is legally available only through Lilly's clinical trials.
- Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials, delivering significant improvements in weight and A1C
Lilly reports two more successful Phase 3 retatrutide obesity trials and says it plans to submit a Biologics License Application to FDA in Q1 2027.
- FDA’s Concerns with Unapproved GLP-1 Drugs Used for Weight Loss
FDA says firms illegally sold unapproved GLP-1 drugs, including retatrutide, falsely labeled "for research purposes" or "not for human consumption."
- Gram Peptides - 721806 - 03/31/2026
FDA found that the company's retatrutide and tirzepatide, labeled "Research Use Only," were drugs for human use, citing its own site claims about reducing body weight.
- Peptide Partners LLC - 735063 - 08/24/2026
FDA says the company's "research use only" products, including one sold as "GLP-3 Reta," are drugs for human use, and that selling bacteriostatic water provides the means to prepare an injectable drug.
- Royal Peptides LLC - 734884 - 08/24/2026
FDA says the company marketed bacteriostatic water alongside a "peptide guide" and "peptide calculator," which together provide the means to prepare an injectable drug.
- Think twice before injecting peptides bought online: unauthorized products can seriously harm you
Health Canada lists BPC-157, TB-500 and retatrutide among seized unauthorized injectable peptides and says "research use only" labels do not make them legal.
- Unapproved peptide product promoters and suppliers are put on notice
TGA warns that unapproved peptides may contain the wrong ingredients, be contaminated or fail sterility standards, and says labeling a blank vial counts as manufacture.
- MHRA smashes major illicit weight loss medicine production facility in record seizure
MHRA seized more than 2,000 unlicensed retatrutide and tirzepatide pens at an illicit Northampton production facility and notes retatrutide has not been approved for UK use.
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks
FDA says BPC-157 may pose immunogenicity and peptide impurity risks, and lists BPC-157 and TB-500 as previously on its safety-risk list after their nominations were withdrawn.
- The peptide problem: Hype is outrunning the evidence
McMaster professor Stuart Phillips writes that the "third-party" labs issuing peptide purity certificates are often the vendors themselves, linking to a CBC Radio explainer.
- Bypassing Prescribers and Pharmacists: Online Purchasing of Semaglutide and Tirzepatide “For Research Purposes” Editorial
38 sites sold semaglutide or tirzepatide "for research purposes"; 4 asked buyers to check a researcher box, none required proof of age, 37 said "not for human consumption," and 17 served targeted ads.