Tesamorelin test results: what 32 lab-tested vials show

Tesamorelin doesn't have the sample size that tirzepatide and retatrutide do, and this article isn't going to pretend otherwise. Thirty-two vials, from 12 vendors, drawn from about 24 lab reports run by 3 labs between November 2024 and July 2026. That's a real dataset, but it's a small one, and the honest thing to do with a small dataset is say so up front rather than dress it up with confident-sounding averages.

This is a thinly tested compound, which is exactly why this snapshot matters — and why it comes with more caveats per paragraph than our tirzepatide or retatrutide pieces do. Everything below concerns research tesamorelin sold for research use only. None of it is about dosing or how to use anything; a lab report can't answer that, and neither can we.

The headline numbers

Purity is solid but noticeably softer than the two GLP-1 compounds we've covered elsewhere. Dose accuracy looks reasonable in aggregate, with a small cluster of vials running well short. And the vendor picture is the real headline: with this few reports per vendor, nobody has qualified for a ranking yet.

Of 32 vials, 4 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 12.5%, a higher failure rate than tirzepatide (1.9%) or retatrutide (4.2%). All four of those failed vials came from a single vendor, which we're not naming here for the same reason we don't name any vendor in an article: a live score on the vendor ratings page is tied to specific, checkable reports and updates as new ones arrive, and a vendor's standing months from now may look nothing like it does today.

Purity: solid, but lower than the GLP-1s

All 32 vials have a purity result. Twenty-nine, or 91%, came in at 99% or higher — a respectable figure on its own. But only 12, or 38%, reached 99.5% or higher, a much smaller share than tirzepatide's 77% or retatrutide's 71% at that same threshold. Median purity across the sample is 99.27%, below tirzepatide's 99.76% and retatrutide's 99.71%.

One vial tested under 95% purity, the sample's only purity failure. Read together, tesamorelin's purity picture is good but not as consistently excellent as the two GLP-1 compounds we've published data on — worth knowing if you're used to seeing 99.5%+ results as the norm.

Dose vs. label: close on the whole, with three vials well short

Of the 30 vials with both a label amount and a measured amount, the median came in at +5.5% over label — close to tirzepatide's +5.4%, and gentler than retatrutide's +8.2%. Eleven vials, 37%, landed within ±5% of label, and 17, 57%, landed within ±10%.

The tail is where it gets more specific. Four vials measured more than 10% under label, and three of those were more than 20% under — a 10% share of the 30-vial sample, higher than tirzepatide's or retatrutide's comparable shares. On the other side, only one vial measured more than 20% over label, and none measured more than 50% over. Tesamorelin's dose-accuracy story, in other words, runs the opposite direction from the two GLP-1 compounds: where they skew toward overfill, tesamorelin's outliers in our data skew toward running short.

Twenty-five of the 30 measured vials are labeled 10 mg, and that group's median sits close to label at +1.7%, with 10 of the 25 within ±5%. But all three of the vials that measured more than 20% under label also came from this same 10 mg group — so the group that looks closest to label on its median is also where every serious shortfall in the dataset sits. That's a real tension in a sample this size: a median can look reassuring while a handful of individual vials tell a very different story.

By year, 2025 vials (20 of them) had a median of +0.9%, and 2026 vials (11 of them) ran hotter at +8.3%. Both are small groups on their own, and a single unusual result can move a median like this substantially — we'd treat this year-over-year comparison as suggestive at most, not the kind of pattern we're confident describing for tirzepatide or retatrutide with their much larger samples.

Vendors: too few reports for a ranking, yet

This is the section where "thin data" stops being a caveat and becomes the actual finding. Twelve vendors have tesamorelin results in our data. Only 2 have five or more vials tested; 3 have just a single vial. And despite that, no vendor is currently ranked for tesamorelin — ranking on VendorVerify requires at least five lab reports for that specific compound, and not one tesamorelin vendor has reached that bar yet, even the two with five or more vials on file. Eleven of the twelve vendors have zero failed tesamorelin vials; as noted above, all four failures in the dataset sit with one vendor.

That's the plainest way to say it: if you're searching for "best tesamorelin vendor," there isn't a ranked answer to give you yet, honestly. Here's how the ranked vendors look right now for tesamorelin specifically — expect this to come up empty, since nobody has cleared the five-report bar:

There's a live, unranked list on the tesamorelin results page, and it will start producing rankings as more reports come in — but as of today, the data simply hasn't reached the threshold we'd need to say any vendor's tesamorelin results are proven out.

Endotoxin and sterility: almost no data yet

Only 2 tesamorelin results in our entire database include an endotoxin test: one came back below the lab's detection limit, and the other measured in the 2–10 EU range. Both sit at the low end, but two results tell you almost nothing about a market of unknown size. No tesamorelin sample in our data has been tested for sterility at all.

We're not going to draw any conclusion from two endotoxin results beyond the fact that they exist and are both fairly low. This is the section of this article that most needs more submitted reports before it says anything useful.

Tesamorelin's regulatory status

Tesamorelin is the active ingredient in Egrifta, a branded drug FDA approved in November 2010 for excess abdominal fat in HIV-infected patients with lipodystrophy. That's a fact about the approved product, not about any vial in our database — a lab report tells you what one research-market sample measured on the day it was tested, and says nothing about whether that sample matches the manufacturing standard behind an approved drug. We're not making any claim here about effects or appropriate use; that's outside what a lab report, or this article, addresses.

Why thin data changes how you should read this

With tirzepatide's 788 vials or retatrutide's 336, a median or a failure rate is built on enough independent reports that a single unusual result barely moves it. With tesamorelin's 32 vials — barely a tenth of retatrutide's sample — a single bad vial or a single generous vendor can shift a headline number noticeably. The all-four-failures-at-one-vendor fact above is a good example: the overall 12.5% failure rate reflects one vendor's results more than the market's, since eleven of twelve vendors have a clean record so far.

Practically, that means two things for a reader deciding what to trust. First, weigh an individual vendor's specific reports more heavily than the market-wide average — with this few data points, "the market" is really a handful of vendors' worth of results. Second, batch matching matters more here than it does for a heavily tested compound: a report on one lot doesn't tell you much about a different lot from the same seller when there are only one or two reports total to compare it against. Neither of these is a knock on tesamorelin specifically — it's what any market looks like before enough people have tested it.

What this data can't tell you

Thirty-two vials is a real number, not a rounding error, and everything above is an honest description of what those 32 vials showed. But it's not enough to say with confidence how the tesamorelin market as a whole is behaving, the way our tirzepatide and retatrutide numbers can, and it's not enough to rank a single vendor. It also doesn't tell you anything about dosing, effects, or how tesamorelin should be used — that's not a question a lab report answers, for this or any compound.

Help close the gap

This dataset only grows if buyers who get vials tested submit the results. If you've had a tesamorelin vial tested, submitting the report is the single most useful thing you can do for this specific page: it takes a signed-in account, the lab report itself as a PDF or image, and the numbers off it, and an admin checks it against the report before it's added. Right now, more than almost anywhere else on this site, a handful of new submissions could meaningfully change what this article is able to say.

What to check on a tesamorelin report

Given how thin the data still is, a few things matter more here than they would for a heavily tested compound:

• How many reports exist for that specific vendor. With no ranked tesamorelin vendors yet, a single report tells you less than it would for a compound with hundreds of data points behind it.
• Batch and lot number. With so few reports per vendor, a result from a different lot than the one you're considering carries even less weight than usual.
• Whether quantity is reported at all, separately from purity. Given tesamorelin's lower share of 99.5%+ purity results, and three vials in our data running more than 20% under label, both numbers are worth checking rather than assuming.
• The lab and report key. Each result on a vendor's page names its lab and, where available, its report key, so you can check the figure against the lab's own record.

We publish every tesamorelin result we can verify on the tesamorelin results page, which will update as new reports arrive — this article is a snapshot of a data set that's still filling in.

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 tesamorelin compares with other compounds on dose vs. label, and our retatrutide test results for a compound with a much larger sample.