Retatrutide test results: what 336 lab-tested vials show

Retatrutide is the second most-tested compound in our database, well behind tirzepatide's 788 vials but well ahead of everything else: 336 vials from 37 vendors, drawn from roughly 189 lab reports run by 12 different labs between October 2024 and September 2026. Buyers call it "reta" for short, and sometimes "GLP-3" — an informal shorthand for its three-receptor mechanism, not an official drug class.

This article is a dated snapshot of what those 336 lab-commissioned tests show. The retatrutide results page stays current as new reports come in; this piece won't. Everything below concerns research retatrutide sold for research use only, and none of it is about dosing or use — that's not a question a lab report can answer, and it's not what this article covers.

Why retatrutide gets tested this much

Retatrutide is a triple agonist — it acts on GIP, GLP-1, and glucagon receptors, one more target than tirzepatide's two. It's being developed by Eli Lilly, which has announced Phase 3 results from several trials (Lilly's own overview). That publicity is likely a big part of why it's the second-most-tested compound in our database: a molecule with widely covered late-stage trial results draws buyer interest well before it reaches a pharmacy shelf, and buyer interest in a grey-market compound tends to produce buyer demand for lab reports.

The headline numbers

Purity is strong. Dose accuracy is the more complicated part of the picture, and it moved in an interesting direction over the two years covered by our data — up, then back down.

Of 336 vials, 14 count as a scoring failure under our rules: empty, under 95% purity, more than 20% under label, or more than 50% over it. That's 4.2% of the sample. Seven of those fourteen failed on purity, six failed for running more than 20% under label, and one failed for running more than 50% over. No vial in our retatrutide data was reported empty.

Purity: consistently high, with a small tail

Every one of the 336 vials has a purity result. 317 of them — 94% — came in at 99% or higher, and 239, or 71%, hit 99.5% or higher. Median purity across the full sample is 99.71%.

The tail is small but real: 7 vials, all of the purity failures in the dataset, tested under 95%. That's about 2% of the sample, and it's worth naming plainly rather than folding into the "94% clean" headline — a small number of genuinely bad-purity vials exist alongside a large majority of very clean ones, and both facts are true at once.

Dose vs. label: wide spread, median running over

Purity and fill amount are different measurements, and retatrutide's data makes that split obvious. Of the 292 vials with both a stated label amount and a measured amount (44 vials in our data had no label figure to compare against), the median measured amount came in at +8.2% over label — a meaningfully bigger overrun than tirzepatide's +5.4%.

Read plainly: fewer than a third of vials land within ±5% of their label, and just over half land within ±10%. At the tails, over-label results outnumber under-label ones by a wide margin — 30 vials more than 20% over versus 6 more than 20% under — which is the same overfill-over-underfill pattern we see market-wide, just more pronounced here than in tirzepatide's numbers.

By vial size: the middle sizes run hottest

Breaking the 292 measured vials out by their labeled vial size shows the same broad shape as tirzepatide, with the largest vials closest to label, but the middle sizes vary a lot:

Two sizes stand out. The 12 mg vials, a small sample of 8, show the highest median overrun on the table at +19.8%. The 15 mg vials, a larger sample of 38, run nearly as hot at +13.3%, and only 6 of the 38 land within ±5% of label. Five of the six vials that measured more than 20% under label anywhere in our data came from the 30 mg group, the single largest vial-size sample here at 81 vials, even though that group's median sits at +6.5%. At the other end, 60 mg vials, though a small sample of 9, sit closest to label: median +2.5%, with 8 of the 9 within ±5%.

We don't have a confirmed reason for this pattern from the reports themselves. A lab report says what a vial measured, not why a manufacturer's fill process behaves the way it does at a given concentration. What the data supports is narrower but still useful: vial size is worth noting on any retatrutide report, and the 12 mg and 15 mg sizes have run furthest from label in our sample so far.

Year over year: overfill peaked in 2025, eased in 2026

Grouping vials by the year each was tested shows a clear rise-and-partial-fall:

The median jumped from +6.6% in 2024 (a small early sample) to +10.9% in 2025, then came back down to +5.7% in 2026 — nearly back to where 2024 started. The count landing within ±5% rose too, from 38 in 2025 to 48 in 2026 on a similar number of vials. We haven't broken that shift down by vendor, and we can't say from the report data alone whether that reflects manufacturers tightening fill processes, buyers shifting toward vial sizes that run closer to label, or some mix — but the direction, for retatrutide specifically, has been toward the label over the most recent year in our data, which is the opposite of what tirzepatide's numbers show over the same window.

Vendors: failures spread thin, no vendor with more than three

We don't name vendors in articles — that's what the live vendor ratings are for, where every score is tied to specific, checkable reports and updates as new ones arrive. Here's how the ranked vendors look right now for retatrutide specifically:

A ranking isn't automatically a green light — the table also flags any vendor with more than 5% failed vials, and a vendor needs at least five separate retatrutide lab reports before it's ranked at all. But the shape of the wider spread is worth describing too.

Of the 37 vendors with retatrutide results in our data, 14 have only a single vial tested, and 13 have five or more vials. Nine vendors are currently ranked for retatrutide specifically; ranking takes at least five separate lab reports, not just five vials. Twenty-eight of the 37 vendors have zero failed retatrutide vials on file; the 14 failures in the dataset sit across 9 vendors, and no single vendor accounts for more than three of them. Among the nine ranked vendors, seven have a 0% retatrutide failure rate, and scores for this compound range from 73.7 to 96.5, with a median of 87.5.

The pattern here isn't a small number of bad actors driving most of the failures — it's failures distributed thinly across a minority of vendors, against a majority with a clean record so far. A vendor with five or six reports on file is one bad result away from a very different-looking record, so treat any single vendor's current standing as current, not permanent.

Endotoxin: mostly low, with a real tail

Sixty-one of the 202 endotoxin results in our overall database are retatrutide, run mostly by Janoshik. Twenty-four came back below the lab's detection limit and one was reported simply as "Pass" — together, about 41% of retatrutide's endotoxin results sit at the clean end, a notably larger below-limit share than tirzepatide's. Of the rest: 12 came in under 2 EU, 11 at 2–10 EU, 6 at 10–20 EU, 1 at 20–100 EU, and 2 at 100 EU or more, the highest a single result of 1,438 EU/vial. Three more results were reported only as ">10 EU" and one only as ">1000 EU/vial" — thresholds rather than precise numbers.

So most retatrutide endotoxin results sit at the low end, with a small, real high-end tail: a handful of results in the hundreds or low thousands of EU sit alongside a much larger cluster of low or below-limit readings. As with every endotoxin figure we publish, units aren't consistent across reports — some state EU per vial, others don't state a basis at all — so results aren't safely comparable side by side unless the units and vial size both match. We're not assigning a "safe" or "unsafe" label to any of these numbers; pharmacopeial endotoxin limits apply to approved drug products under regulated conditions, not to a research vial of unknown provenance, and it's also worth remembering these are the vials buyers chose to test, not a random sample of everything sold.

Sterility, TFA, and other tests: a small, heavily caveated picture

Only 7 retatrutide samples in our data have been tested for sterility — reported as TAMC and TYMC, total aerobic microbial count and total yeast and mold count. All 7 failed at least one of the two counts. That's a very small sample, almost certainly skewed toward buyers who already had a reason to be suspicious before paying for a sterility test, and a failed microbial count on a sample prepared for lab testing is a lab finding about that specific sample — not a medical diagnosis, and not a statement we're extending to the wider retatrutide market. We report it because it's real data from real tests, and because seven honest results are more useful than silence, as long as the sample size that produced them is stated plainly.

Other tests on retatrutide are rarer still and consistently clean where they exist: 5 TFA results, all "0" or "not detected"; 4 heavy-metals results, all not detected; and 6 LC-MS impurity screens, typically describing "retatrutide and degradation products," several of them also noting mannitol — a common bulking agent in freeze-dried vials, so seeing it listed is expected.

Retatrutide's regulatory status

As of this writing, retatrutide is not approved by the FDA. Eli Lilly describes it as an investigational medication, has reported positive results from five Phase 3 trials (most recently TRIUMPH-2 and TRIUMPH-3 on July 23, 2026), says more trials are still underway, and plans to submit a Biologics License Application to FDA in Q1 2027 (Lilly's own overview, last updated July 2026). Nothing in that trial program changes what's in a research-market vial sold today: a lab report tells you what one sample measured on the day it was tested, not whether the compound has cleared any regulatory review, and not what any dose in a trial protocol does or doesn't do. Those are separate questions, and this article, like every lab report we publish, only answers the first one.

What this data can't tell you

A lab report describes one vial, on one day, as measured by one lab. It doesn't describe a different vial from the same batch, a different vendor's product, or the same vendor's next shipment. Our vial-size and year-over-year breakdowns are patterns across hundreds of individual reports, which is useful precision, but 336 vials is still a sample, not a census of every retatrutide vial sold — we don't know how large the total market is, and every vial here was tested because someone chose to test it (almost always a buyer, occasionally the vendor itself), which likely skews the data toward buyers who had some reason to check.

It's also worth restating plainly: nothing here is about dosing, effects, or how any compound should be used. A lab report answers what's in the vial. That's the whole scope of it.

What to check on a retatrutide report

Given everything above, a few things are worth looking for specifically on any retatrutide certificate:

• Vial size. Our data shows 12 mg and 15 mg vials running furthest over label and 60 mg vials sitting closest — knowing the size matters here more than for some other compounds.
• Test date. Given the swing from a 2025 peak back toward label in 2026, a year-old report may say less about a current batch than a recent one.
• Whether quantity is reported separately from purity. Retatrutide's purity numbers are strong; its dose-vs-label numbers are the part worth reading carefully.
• The lab and report key. Each result on a vendor's page names its lab and, where the report has one, its report key, so you can check the number against the lab's own record.

We publish every retatrutide result we can verify, matched against its vendor, on the retatrutide results page, which updates continuously — this article is a snapshot, that page isn't. If you've had a retatrutide vial tested and want it added to the record, you can submit the report.

Figures in this article are from the VendorVerify database as of September 28, 2026. See also how to read a peptide COA for what each line of a certificate measures, underdosed peptides for how retatrutide compares with other compounds on dose vs. label, and our tirzepatide test results for the market's most-tested compound.