Retatrutide is the most tested peptide on the gray market, and the tests point two ways. Vials from established sellers usually pass independent testing. Vials from unlabelled social-media listings usually do not, and one of them put someone in hospital. Where you buy decides which of those you get. The rest of this page is the evidence behind that, what a careful purchase looks like, what it costs, and where the law stands. Updated 27 September 2026.
What do tests of online retatrutide show?
Finnrick buys peptides from sellers without telling them and sends the vials to independent laboratories. By 20 September 2026 it had published 3,858 retatrutide tests from 293 sellers, more than for any other peptide.11 Of the 200 most recent, about 7 in 10 passed its standard: the right compound, at least 99.5% pure, within 35% of the labelled amount. Sellers with long records pass about 9 in 10. Sellers at the bottom of the list pass fewer than half. The bad results in the news this year came from somewhere else. An Australian laboratory tested 18 vials bought through social media and unlabelled listings. One matched its label. About a third were stronger than labelled, a third weaker, and one contained no retatrutide at all.1 Then in September the regulator traced a vial that had put a patient in hospital with a torn oesophagus after uncontrollable vomiting. It contained no retatrutide at all, and it contained semaglutide at about eight times the approved dose.2
| Where it came from | What testing found |
|---|---|
| Sellers with a published test record | About 7 in 10 pass; the best pass 9 in 1011 |
| Unlabelled vials from social-media listings | 1 of 18 matched its label1 |
| The vial that caused the hospital case | Semaglutide, eight times the approved dose, no retatrutide2 |
| A pass on Finnrick's standard covers identity, purity and amount. It does not cover sterility or endotoxins, which are separate tests. The counts above are Finnrick's as of 20 September 2026 and move every week; the live page has the current figures. |
How do careful buyers check retatrutide before using it?
People who buy retatrutide and get what they paid for treat it as a testing problem. Four steps.
- Check the seller's test record first. Look the seller up on Finnrick and read the number of tests behind the rating, not just the rating.11 Then check that the seller is on the vendor page and has no open letter on the regulatory tracker. Sellers that label the product GLP-3 RT instead of retatrutide are not doing anything unusual; the vendor-codes guide explains why.
- Get a certificate that matches your vial. A useful COA names the compound, shows a mass-spectrometry identity result and an HPLC purity figure, names the laboratory, and carries a lot number that is printed on your vial. The COA guide shows how to read one. A COA cannot tell you whether the vial in your hand is from that batch or how much powder is in it, which is why step 3 exists.
- Test the first vial from any new seller. This is the only way to know what is in your vial rather than in the seller's past batches. Finnrick accepts mailed samples from US buyers, sometimes at no charge. With retatrutide the test matters twice, because it confirms the compound as well as the amount, and both have been wrong in published samples.
- Dose from the tested amount, not the label. If a "10 mg" vial holds 19 mg, as one tested Australian vial did,5 every draw is nearly double. Run the calculator with the tested amount once you have it. Sellers list retatrutide in vials up to 100 mg,9 against a highest trial dose of 12 mg a week; a concentration error on a large vial is repeated across months of doses. None of this makes the vial approved. It does mean you know what you bought.
How much does retatrutide cost online?
In our 27 September 2026 price capture,9 78 tracked sellers carried retatrutide across 311 listings. The middle of the market was $6.95 per mg, with most listings between $3.83 and $13.80. The 10 mg vial is the size most sellers stock, with 64 listings. The price page has the current listings. Price says nothing about what is in the vial. The sellers at the top of Finnrick's retatrutide ranking are spread across the price range, from under a dollar per mg to nearly eight.11
Is retatrutide legal to buy online?
Selling it is not. In June 2026 the FDA said that selling unapproved retatrutide to consumers is illegal and that it cannot be compounded.3 In August, Lilly sued six US sellers and said it had reported more than 14,000 listings to platforms and payment companies.7 In September the FDA posted warning letters naming retatrutide among the products.8 Buying is not what the enforcement targets, but there is no legal seller to buy from, no compounding pharmacy that can make it, and no clinic with a source a pharmacy does not have. The only legal way to get retatrutide is a Lilly clinical trial. The compound page lists the registered trials and their status. When it might be approved is covered in the filing guide. Enforcement has not removed retatrutide from sale. It has changed how it is listed and how it is paid for. Of the 132 sellers we track, 53 now list semaglutide, tirzepatide or retatrutide under codes, and retatrutide is the compound most often coded. And because Lilly reported listings to payment companies as well as platforms,7 card processing at retatrutide sellers has thinned out. Sellers push wire transfers, Zelle or crypto instead. None of those can be reversed, so a wrong or missing order has no chargeback behind it. Price that in, and count it as one more reason step 3 above matters more here than for a card purchase.
Is buying retatrutide online riskier than semaglutide or tirzepatide?
| Semaglutide or tirzepatide | Retatrutide | |
|---|---|---|
| An approved product exists to compare against | Yes | No |
| A legal compounding route exists | Yes, on a prescription (how that works) | No3 |
| Blind tests published11 | Semaglutide 345; tirzepatide 2,478 | 3,858, the most of any peptide |
| The first two rows are why a bad retatrutide vial is a bigger problem than a bad semaglutide vial: there is no known drug for a doctor to work from, and as the hospital case showed, the vial may be a different drug entirely. The last row is the offset. More retatrutide has been blind-tested than any other peptide, so a buyer has more to check a seller against. |
What is retatrutide?
Retatrutide is Lilly's experimental weekly injection. It acts on three receptors (GLP-1, GIP and glucagon), one more than tirzepatide. Lilly's code for it is LY3437943; sellers call it Reta, GLP-3, GLP-3 R or GLP-3 RT.4 It is in Phase 3 and approved nowhere. People want it because of the Phase 2 result: a mean 24.2% loss of body weight at 48 weeks on the 12 mg dose, against 2.1% on placebo.10 That is above anything semaglutide or tirzepatide showed at the same point. The trials also reported high rates of nausea, vomiting and diarrhoea at the higher doses, and a dehydration pattern serious enough that we wrote a separate guide on it.
What if something goes wrong?
The reported cases share the same picture: uncontrollable vomiting, inability to keep fluids down, severe diarrhoea. Go to an emergency department for any of them rather than waiting it out. Tell the doctor exactly what you injected and bring the vial. The dehydration guide covers the electrolyte risk.
Common questions
Is retatrutide legal to buy in the US?
No. The FDA has said selling it is illegal and it cannot be compounded. There is no legal seller.
Is retatrutide sold under another name?
Yes. GLP-3, GLP-3 R, GLP-3 RT, GLP-3 RTA and Reta all mean retatrutide on seller pages. LY3437943 is Lilly's development code. GLP-3 is not a hormone.
How common is fake or counterfeit retatrutide?
It depends where you buy. About 7 in 10 recent blind-tested samples from tracked sellers pass; the best sellers pass 9 in 10. Of 18 vials bought through social media and tested in Australia, one matched its label, and a separate vial turned out to be semaglutide.
Which sellers test well?
Finnrick publishes a ranked list with pass rates per seller. We do not reproduce or endorse it. Read the number of tests behind a rating, and check the seller against the vendor page and the regulatory tracker here.
How do I know if my vial is real?
Not from the vial. A seller's test record covers their past batches; a COA rules out some problems; only a test of your own vial tells you the compound and the amount in your hand.
How much does retatrutide cost online?
In our 27 September 2026 capture, a median of $6.95 per mg, with most listings between $3.83 and $13.80 per mg.
How much weight did it cause in trials?
A mean of 24.2% at 48 weeks on 12 mg in the Phase 2 trial, against 2.1% on placebo. Phase 3 results are not yet published.
Can I get it from a clinic or compounding pharmacy?
No. The FDA has said it cannot be compounded, and a clinic has no source a pharmacy does not have. The only legal route is a Lilly trial.
Sources
- ABC News (Australia), New testing of black market peptides reveals dangerous dosing levels, 28 August 2026, reporting Leeder Analytical's 2026 results and the University of Queensland tests. https://www.abc.net.au/news/2026-08-28/black-market-peptides-dangerous-doses/107059092
- Therapeutic Goods Administration, TGA tests counterfeit retatrutide product following serious adverse event report, safety advisory, 14 September 2026. https://www.tga.gov.au/safety/safety-monitoring-and-information/safety-alerts/tga-tests-counterfeit-retatrutide-product-following-serious-adverse-event-report
- U.S. Food and Drug Administration, FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (retatrutide cannot be used in compounding; unapproved retatrutide sold to consumers is illegal). https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
Also reported by CNBC, 12 August 2026. https://www.cnbc.com/2026/08/12/lilly-lawsuits-obesity-drug-retatrutide.html - Sport Integrity Australia, Retatrutide, substance education page listing LY-3437943 and Reta as other names. https://www.sportintegrity.gov.au/what-we-do/anti-doping/substance-education/retatrutide
- ABC News (Australia), Vial of unapproved peptide retatrutide had double the strength indicated on label, 27 June 2026. https://www.abc.net.au/news/2026-06-27/double-strength-retatrutide-peptide-sparks-warning/106844372
- Eli Lilly and Company, Lilly calls on online platforms, payment companies and regulators to shut down the illegal retatrutide black market, news release, 12 August 2026. https://investor.lilly.com/news-releases/news-release-details/lilly-calls-online-platforms-payment-companies-and-regulators
- FDA warning letters posted 1 September 2026 naming retatrutide among products sold online, as listed on the regulatory tracker. https://peptidedecoding.com/status
- Peptide Decoding vendor price capture, 27 September 2026. Internal data; figures reproduced on the retatrutide price page.
- Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. N Engl J Med 2023;389:514-526. https://doi.org/10.1056/NEJMoa2301972
- Finnrick, Retatrutide safety testing results and vendor ratings, blind-purchase testing dataset, 293 vendors and 3,858 tests as of 20 September 2026; recent 200-test summary and the Purity Focus standard (HPLC purity at least 99.5%, fill within 35% of label). https://www.finnrick.com/products/retatrutide