When retatrutide seems to stop working, there are three possible causes: the vial holds the wrong compound or too little of it, the peptide degraded in storage, or the dose is still low on the TRIUMPH step-up ladder. An identity and quantity test is the only way to rule out the first. In our mirrors of 271 Kovera and 68 Janoshik retatrutide certificates, 3 failed identity, one of them with 0.00 mg in the vial, while most vials held more than the label said. Storage data from a crowdfunded study shows refrigerated, reconstituted retatrutide losing single-digit percentages over 60 to 90 days, with one vial in eight collapsing.
A retatrutide vial that "stopped working" is one of three things: the wrong compound or too little of it, a degraded solution, or a dose and timeline that has not caught up yet. Appetite and the scale cannot tell these apart. A lab test can.
We read five Reddit threads posted between 13 September and 2 October 2026 in which buyers said retatrutide was not working, plus two threads on failed third-party tests. We checked those reports against our mirrors of 271 Kovera Labs and 68 Janoshik retatrutide certificates, a crowdfunded stability study, and the published trial data.
Is my retatrutide fake or am I a non-responder?
Run the checks in this order. The first three are free.
- Count the weeks at each step. In TRIUMPH-2, according to the Lancet paper and Lilly's medical summary, participants started at 2 mg and stepped up every four weeks, so the 12 mg arm reached its dose at week 16. If you are under 12 weeks, or still at a low step, a slow scale matches what the trials saw.
- Check the handling after mixing. More than 60 days since reconstitution, a freeze, weeks at room temperature or plain sterile water instead of bacteriostatic water all push loss up. See the storage section below.
- Match your lot to a certificate you resolved yourself. The lot printed on your vial must appear on a record held by the lab, not on a PDF the vendor sent. Our COA verifier does this lookup.
- Test the vial. Ask for identity by LC-MS and content by HPLC. Three
outcomes are possible:
- Wrong compound or "no analyte detected": the vial is the problem.
- Right compound, content well under label: the vial is part of the problem.
- Right compound, content at or above label: the vial is not the problem.
If the vial passes, stop changing vendors. The cause sits in steps one and two, or in how you respond to the drug.
"Reta not working": what are people reporting?
Five threads in three weeks, with 29 to 148 comments each. The pattern repeats:
- A buyer who had used tirzepatide 7.5 mg wrote in "Reta not working" (13 September, 148 comments) that after starting at 2 mg on 24 July and reaching 8 mg, "I haven't lost a single pound." The top reply pointed to prior GLP-1 exposure, not the vial.
- "All the sudden I have no appetite suppression from Reta" (24 September, 41 comments) describes good results at 4 mg, then a stall that did not respond to higher doses after the poster switched from a vendor's Chinese warehouse to its US one.
- "Reta dose" (2 October, 38 comments): a restart after eight months off, with "no appetite suppression" at 6 mg and product "purchased from two reputable sources".
- "Reta and not losing weight" (14 September, 40 comments) argues "it might be time to switch vendors", after 5 lb a month on the first source.
- "Reta isn't working, now what?" on r/Peptides (20 September) was removed by moderators; the replies blame a two-month break from a GLP-1 and diet.
None of these posters reported a lab test. In every thread, at least one reply asked whether they had tested. Two other threads did report tests, and they show what a bad vial looks like.
How often do retatrutide vials fail testing?
Buyers on Reddit report the failures; our certificate mirrors show the base rate among vials vendors chose to submit. The two answer different questions.
What buyers reported. In a 203-comment thread on r/PeptidePathways (23 September 2026), one buyer wrote: "Purchased 4 kits of reta and had it test as Sema." The vendor reshipped, and the new batch tested as retatrutide. Another reported cagrilintide that came back as ipamorelin and "reta come back as 100% filler." An account that identifies as a testing lab wrote that "about 20% of what we've tested over the last month has had nothing in it other than filler." That is the account's own claim about its own samples; we have not seen its data and cannot confirm it. In a separate thread a gray-market tirzepatide kit failed with "No Analyte Detected" (23 September, 127 comments).
What our mirrors hold. We mirror Kovera Labs and Janoshik public certificates and audit every record.
| Mirror | Retatrutide records | Test dates | Identity failures | Content under 90% of label | Median content vs label |
|---|---|---|---|---|---|
| Kovera Labs (snapshot 1 Aug 2026) | 271 | 19 Jan to 16 Jul 2026 | 3 | 0 of 263 measured | 110.3% |
| Janoshik (snapshot 30 Jun 2026) | 68 | 4 Feb 2025 to 23 Jun 2026 | 0 | 1 of 60 measured | 110.4% |
The counts include code-named products such as "GLP-3 RT", which is retatrutide sold under another name.
The three Kovera identity failures:
- KVR-2026-06D5D6, client GLP-We1, analysed 22 May 2026: labelled retatrutide 10 mg, measured 0.00 mg and 0.000% purity. The lab found nothing to measure.
- KVR-2026-9197F8, client Instant Peptides, analysed 11 May 2026: "GLP-3 RT", labelled 15 mg. LC-MS identity returned "Unknown" while purity read 99.848%.
- KVR-2026-40AF14, client Glacier Aminos, analysed 11 May 2026: "GLA-3 RT", labelled 10 mg. Identity "Unknown", purity 99.878%.
The last two show why purity alone settles nothing. A vial can be 99.8% pure of something that is not retatrutide.
On Janoshik, test 102150 (Arctic Lab Supply, 26 February 2026) measured 8.78 mg in a 10 mg vial, 87.8% of label. Test 97074 (RetaEU.nl, 7 January 2026) was a qualitative LC-MS screen that found "mannitol, retatrutide, and degradation products."
The bigger pattern runs the other way. Across both mirrors, 175 of 323 vials with a measured content held more than 110% of label, and 17 held more than 120%. If your vial is real, it more likely holds extra peptide than too little. The Kovera vendor analysis and the Janoshik purity analysis cover the wider corpus.
Can retatrutide degrade after mixing?
It can, but in most of the published tests it degraded slowly. PepRecon published stability data on 13 September 2026 from PTDS, a crowdfunded testing group, with Janoshik running the assays. The Reddit post sharing it drew 303 upvotes and 110 comments.
| Condition | Result | Test |
|---|---|---|
| Mixed with bacteriostatic water, 4 °C, 90 days | −2.4% total peptide | 683 |
| Mixed with ultrapure water, same kit, 90 days | −7.9% | 683 |
| Mixed, room temperature, 45 days | −1.6% and −8.7% (two products) | 715 |
| Mixed, steady refrigeration, 90 days | 91.0% and 90.4% of mass retained | 616 |
| Mixed, frozen then refrigerated, 45 days | 85.6% and 86.6% retained | 624 |
| Mixed, refrigerated, 90 days (outlier) | 16.61 mg to 9.26 mg, purity 98.17% to 57.0% | 473 |
| Dry powder, home fridge, 14 to 21 months | purity flat (99.49% to 99.62%, for example) | 625 |
| Dry powder, 130 °F, 21 days | mass flat, purity 96.958% to 93.672% | 293 |
Read the method before leaning on these. Most conditions rest on one vial, the designs differed from test to test, and the authors measure stability by recovered mass because filtration before HPLC removes aggregated peptide and can leave purity looking clean. One commenter who exported the raw data noted that a "well-behaved" vial was already down 8% by day 60.
What this means for a stalled vial: a fridge-stored, bacteriostatic-water vial under two months old is an unlikely cause of a total loss of effect. A frozen vial, one mixed with plain water, or one past 60 to 90 days is a reasonable suspect for partial loss. One vial in eight failing badly is also real. If a mixed vial turns cloudy or forms particles, our cloudy vial guide covers what that can mean, and the reconstitution guide covers mixing and storage.
Am I on a dose that should work yet?
The trial data says response builds with dose and time, and it varies more than the averages suggest.
In the Phase 2 trial (NEJM, 2023; 338 adults with obesity), mean weight change at 24 weeks was −7.2% on 1 mg, −12.9% on 4 mg, −17.3% on 8 mg and −17.5% on 12 mg, against −1.6% on placebo. By week 48, 92% of the 4 mg group, and 100% of the 8 mg and 12 mg groups, had lost at least 5%. On the top doses, nobody in that trial was a complete non-responder over 48 weeks.
Type 2 diabetes changes the picture. TRIUMPH-2 (The Lancet, 29 September 2026; 1,152 adults with obesity and type 2 diabetes) reported −11.9%, −16.8% and −18.8% at 80 weeks on 4, 9 and 12 mg under the treatment-regimen estimand, against −5.1% on placebo. Lilly's release of the same date gives the share losing at least 20% as 24.0%, 45.3% and 52.0% by the efficacy estimand. So close to half of participants on 12 mg with diabetes did not reach 20% in 80 weeks of supervised dosing.
| Trial | Population | Weeks | Top dose result | Responder figure |
|---|---|---|---|---|
| Phase 2, NEJM 2023 | obesity, no diabetes | 48 | −24.2% on 12 mg | 100% lost ≥5% on 8 and 12 mg |
| TRIUMPH-2, Lancet 2026 | obesity + type 2 diabetes | 80 | −18.8% on 12 mg (treatment-regimen) | 52.0% lost ≥20% on 12 mg (efficacy) |
Two gaps in the trial record matter for Reddit posters. None of the trials we read tested people switching from tirzepatide, and none tested restarting after a long break. Claims that prior GLP-1 use "needs a higher dose" are community observations without a published trial behind them. Several posters also equate appetite with effect; one reply in the 24 September thread argued that retatrutide suppresses appetite less than tirzepatide while weight still falls. The trials measured weight, not hunger, so treat that as anecdote. Our dosing protocols page lists the published step-up schedules, and the side-effects page covers what the trials recorded at each dose.
"Reta and not losing weight": should I switch vendors?
Only after a test. The 14 September poster switched vendors and reported "a huge difference" in appetite. That is one data point with two confounders: the second vial arrived later in the step-up, and neither vial was tested. The top reply to that post called 5 lb a month "still good progress."
A failed test is worth more than a switch. In the 23 September thread, the buyer whose reta tested as semaglutide got a reshipment plus testing costs back, because the result was on paper. Without a certificate, a vendor can call it a slow responder and move on. Our where to buy retatrutide page covers how we screen sellers, and retatrutide cost per month shows what a test adds to the bill.
How do I get a vial tested?
Send one unopened vial from the lot you are using. Ask for identity by LC-MS (or mass spectrometry by another name) and net content by HPLC against a reference standard. Purity alone will not catch a wrong compound, as the two "Unknown" Kovera records show. Ask for an endotoxin screen if the vial will be used for anything beyond bench work.
Our testing labs compared page lists which labs offer which assays and what they charge. Before you rely on any certificate a vendor sends instead, resolve its report number on the lab's own site with our COA verifier, or follow how to verify a Janoshik COA. If you need to check the arithmetic on a reconstituted vial, the peptide calculator converts mg and mL to concentration.
What we read
- Five Reddit threads on r/Retatrutide and r/Peptides posted 13 September to 2 October 2026 about retatrutide not working, plus the PTDS stability thread, read with their top comments.
- Two r/PeptidePathways threads on failed third-party tests, 23 September 2026.
- Our Kovera Labs mirror (1,828 certificates, snapshot 1 August 2026) and Janoshik mirror (337 public reports, snapshot 30 June 2026), filtered to single-compound retatrutide records including code names.
- The PepRecon/PTDS retatrutide stability write-up of 13 September 2026.
- The retatrutide Phase 2 paper (NEJM, 2023), the TRIUMPH-2 abstract (The Lancet, 29 September 2026) and Lilly's TRIUMPH-2 release of the same date.
What we did not read
Private test results shared in Discord or Telegram groups, the testing-lab account's underlying data for its 20% filler figure, and any Janoshik or Kovera records published after our snapshot dates. We did not run our own stability test. The PTDS data is third-party and mostly single-vial; we report it as published.
Sources
- Jastreboff et al., Triple-hormone-receptor agonist retatrutide for obesity, a Phase 2 trial (NEJM, 2023)
- TRIUMPH-2, The Lancet, 29 September 2026
- Lilly, TRIUMPH-2 detailed results release, 29 September 2026
- PepRecon / PTDS, Retatrutide: the complete stability picture, 13 September 2026
- r/Retatrutide, Reta not working, 13 September 2026
- r/Retatrutide, Reta and not losing weight, 14 September 2026
- r/Retatrutide, PTDS degradation data thread, 15 September 2026
- r/Peptides, Reta isn't working, now what? (removed), 20 September 2026
- r/PeptidePathways, Anyone ever had Chinese peptides fail third-party testing?, 23 September 2026
- r/PeptidePathways, Tirz from gray market failed COA test, 23 September 2026
- r/Retatrutide, All the sudden I have no appetite suppression from Reta, 24 September 2026
- r/Retatrutide, Reta dose, 2 October 2026
Kovera certificates cited (KVR-2026-06D5D6, KVR-2026-9197F8, KVR-2026-40AF14) resolve at koveralabs.com/verify. Janoshik tests 102150 and 97074 resolve at verify.janoshik.com.
Frequently asked
Is my retatrutide fake or am I a non-responder?
You cannot tell from appetite or the scale. A vial that holds semaglutide, filler or nothing produces the same experience as a slow response. The only way to separate them is an LC-MS identity test plus an HPLC content test on a vial from your lot. If the vial passes both, the vial is not the explanation and the question becomes dose, time and storage.
Reta isn't working, now what?
Work through four checks in order: how many weeks you have been at each step, how the vial was stored after mixing, whether the lot number on your vial matches a certificate you resolved on the lab's own site, and finally a lab test of the vial itself. The first three cost nothing. The fourth is the only one that settles identity.
Can retatrutide degrade after mixing?
Yes, slowly in most tests. In crowdfunded stability work published by PepRecon in September 2026, refrigerated vials mixed with bacteriostatic water lost single-digit percentages of peptide over 60 to 90 days. One vial out of eight lost nearly half its mass. Freezing the mixed solution lost mass faster than steady refrigeration.
Do fake retatrutide vials exist?
Yes. In our Kovera mirror, certificate KVR-2026-06D5D6 records a vial labelled retatrutide 10 mg that held 0.00 mg, and two code-named vials returned "Unknown" on LC-MS identity. Reddit testers in September 2026 reported kits that tested as semaglutide and vials of "100% filler".
Should I switch vendors if reta isn't working?
Switching without testing swaps one unknown for another. A Reddit poster who switched reported better appetite suppression afterwards, but without a test of either vial nobody can say whether the first was bad or the second dose simply arrived later in the step-up. Test the vial you have first. A failed test is also your evidence for a refund.
How much weight did people lose on retatrutide in trials?
In the Phase 2 trial (NEJM, 2023), every participant on 8 mg and 12 mg lost at least 5% by week 48. In TRIUMPH-2, in people with type 2 diabetes, 52.0% on 12 mg lost at least 20% at 80 weeks by Lilly's efficacy estimand, so roughly half did not reach that mark.