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GLP-1 · Grey market

Track 3: grey-market "research" GLP-1s

Some people start with a vial of powder bought online, labelled for research and not for human use: retatrutide, cagrilintide, or cheap semaglutide and tirzepatide. This page does not tell you to, and it does not tell you not to. It sets out what is known about these products, what tests of them found, and the pages to read first.

Last updated November 3, 2026 · Reviewed by Grey Peptides Editorial Board · ✓ Every claim sourced · No products sold, no seller named

📋 Key takeaways

No approved product. FDA says retatrutide and cagrilintide are not components of any FDA-approved drug, have not been found safe and effective for any condition, and cannot be used in compounding.1

"For research" is not a safety grade. FDA calls these labels false when the products are sold for people, and urges consumers not to buy products of unknown quality.1

Tests found the wrong amounts. Three online semaglutide vials held 28.6% to 38.7% more than their labels, and one had a measurable level of endotoxin, a fever-causing bacterial toxin;3 three products sold as retatrutide in Australia held from about half to almost double the labelled amount.4

If you go ahead anyway, read the grey-market buyer's guide, mix with the calculator, and start with the syringes section. These pages reduce some risks; none makes the product approved.

On this page

  1. What is being sold
  2. What tests of these products found
  3. Side effects: the trial evidence
  4. If you are going ahead anyway: read these first
  5. The approved route is still open
  6. Frequently asked questions
  7. Related on Grey Peptides
  8. Sources

What is being sold

Online sellers list GLP-1-type peptides as powder in a vial, labelled for research use and not for human use. The common ones are retatrutide, an investigational drug that acts on three hormone receptors (GIP, GLP-1 and glucagon);2 cagrilintide; and research-labelled semaglutide and tirzepatide, the molecules in the approved pens.

FDA's position is plain. Retatrutide and cagrilintide cannot be used in compounding under federal law, are not components of FDA-approved drugs, and have not been found safe and effective for any condition.1 Products sold "for research purposes" or "not for human consumption" are, in FDA's word, falsely labelled when they are marketed for people, and FDA urges consumers not to buy them because they are of unknown quality and may be harmful.1 Our guide to the research-use label explains what it means legally, and the retatrutide hub covers the drug's trials and status.

Put simply, for retatrutide there is no approved product to compare a vial with; for semaglutide and tirzepatide there is, and the research vial is not it (our reasoning).

What tests of these products found

Few research-labelled GLP-1 vials have been tested independently and published. These are the ones we found:

  • Semaglutide bought without a prescription. Researchers made test purchases from illegal online pharmacies. Three vials arrived, and none of three ordered pens did. The vials held 28.56% to 38.69% more semaglutide than labelled.3 Semaglutide made up 7.7% to 14.37% of the powder in each vial by weight; that is its share of the powder, a different measure from the sellers' claim of 99% purity.3 Endotoxin, a fever-causing bacterial toxin, was measured at 8.95 EU/mg in one vial; the other two were reported only as below the test's limit (figures from the full paper, as recorded in our lab-results dataset, rows LR-0004, LR-0008 and LR-0012).3
  • Retatrutide in Australia. Three products sold as retatrutide and labelled 10 mg were analysed by an accredited laboratory. All three contained retatrutide, but at 5.13 mg, 19.0 mg and 16.5 mg: from about half to nearly double the label.4 At those amounts a carefully measured dose could be half or twice what the buyer intended (our reasoning).
  • Liver injury in Victoria. In June 2026 Victoria's health department reported acute liver injury in people who had used products labelled retatrutide, and said the toxic effects were possibly linked to a contaminant; the cause was not established.5

A test of one batch says nothing about the next. Our verification guide explains what a lab report can and cannot show, and the test results page lists each published measurement.

Side effects: the trial evidence

For retatrutide, the side-effect evidence comes from trials run by its maker, with medical supervision, a known product and a slow start. In the 48-week phase 2 obesity trial, 338 adults were randomised to retatrutide or placebo. The most common side effects were in the gut; they rose with dose, were mostly mild to moderate, and were partly eased by starting at a lower dose. Heart rate rose with dose, peaked at 24 weeks and then fell.2 At the highest dose, weight fell by 24.2% at 48 weeks against 2.1% on placebo.2

Everything on the hub's long-term risks list (thyroid, pancreas, gallbladder, kidneys) comes from the labels of semaglutide and tirzepatide. A research vial has no label, so nobody has written those warnings for it; that does not mean the risks are absent (our reasoning). The retatrutide entry's dosing box shows which amounts were used in trials and says that no dose is approved; this page prints none.

If you are going ahead anyway: read these first

This site names no seller and recommends no source. If you have decided to use a research vial, these pages cover the steps where people get hurt:

  1. How the grey market works, and the grey-market buyer's guide: twelve steps for a first-time buyer, from checking for an approved alternative to reporting a reaction.
  2. Kits versus single vials: the price per milligram, what a test of one vial does and does not say about a kit, and the published test results above.
  3. The name decoder: listings use code names such as "GLP-3" for retatrutide; the GLP-3 guide explains them.
  4. The reconstitution calculator: enter the amount in the vial, the water you add and the dose; it gives the mark on the syringe. FDA's reports of people injecting five to 20 times the intended dose came from exactly this step, with compounded semaglutide.6
  5. Syringes for first-timers: which syringe, units versus millilitres, injecting under the skin, and disposal.
  6. Contamination and reactions: what a bad vial can do and when to get care.

FDA also recommends not using any injectable GLP-1 that arrives warm or without enough refrigeration.1 If something goes wrong, report it to FDA's MedWatch programme.6

The approved route is still open

For most people weighing a research vial, the alternative is an approved semaglutide or tirzepatide product, which has a label, a reviewed factory and a known amount in every dose (the prescribed track). The approved alternatives tool and the transition planner help with that conversation. Retatrutide has no approved version to move to; its hub follows the trials and the maker's filing plans.

Frequently asked questions

Is research-grade retatrutide legal to buy?

FDA says retatrutide is not a component of any approved drug, cannot be used in compounding, and that 'for research purposes' labels are false when such products are sold for people. This page is not legal advice.1

Is research semaglutide the same as Ozempic?

No. Test purchases of online semaglutide vials found 28.56% to 38.69% more drug than labelled, and a measurable endotoxin level in one; an approved pen is made under an FDA-reviewed application.3

What dose of retatrutide should I take?

Grey Peptides gives none. Retatrutide has no approved dose; its encyclopedia entry shows the amounts used in trials, where people started low under supervision.2

Starting a GLP-1 hub Track 1: a prescribed GLP-1 Track 2: a compounded GLP-1 GLP-1 titration planner GLP-1 pens, vials and dose math GLP-1s and muscle loss Stopping a GLP-1 and weight regain GLP-1 drug interactions Reconstitution calculator Syringes for first-timers

Sources

FDA pages are cited with the date each shows; studies by PMID, checked on PubMed. All read November 3, 2026.

  1. U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (sections on retatrutide and cagrilintide, products labelled for research, storage on arrival). Content current as of October 1, 2026; read November 3, 2026. Source
  2. Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. PMID 37366315. Funded by Eli Lilly. Read November 3, 2026. Source
  3. Ashraf AR, Mackey TK, Vida RG, Kulcsár G, et al. Multifactor Quality and Safety Analysis of Semaglutide Products Sold by Online Sellers Without a Prescription: Market Surveillance, Content Analysis, and Product Purchase Evaluation Study. J Med Internet Res. 2024;26:e65440. PMID 39509151 (full text PMC11582493). Read November 3, 2026. Source
  4. Piatkowski T, Craven A, Cornell S, Ferris J. Composition and Labelling Accuracy of Products Sold as Retatrutide in Australia. Drug Alcohol Rev. 2026;45(6):e70231. PMID 42559975 (a letter; figures as recorded in our lab-results dataset, rows LR-0013 to LR-0016). Read November 3, 2026. Source
  5. Victorian Department of Health (Australia). Health alert: Toxicity linked to unapproved peptide product labelled Retatrutide. Issued June 19, 2026 by the Chief Health Officer; as recorded on our kits-versus-single-vials page, re-read there October 27, 2026. Cited without a link, as that page cites it.
  6. U.S. Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. July 26, 2024; read November 3, 2026. Source

This section explains GLP-1 medicines in plain words; it is not medical advice, and it does not replace the prescriber or pharmacist who knows your history. Grey Peptides sells nothing, links to no seller and rates none. If you feel unwell after an injection, contact a clinician or Poison Help (1-800-222-1222 in the US); in an emergency call 911.