If you have spent any time researching growth-hormone-releasing peptides, you have probably run into both names and assumed they are interchangeable. They are not, and the gap between them is the single most important thing to understand before spending money on either one. Both are GHRH analogs — synthetic versions of the signal your hypothalamus sends to your pituitary to release growth hormone. But one of them stopped being sold as an approved drug decades ago, and now exists only as compounded material. The other is a currently-marketed, FDA-approved prescription product with modern outcome trials behind it. That is not a marketing distinction. It is the difference between a drug your doctor can prescribe on-label and one that legally cannot be prescribed on-label for anything, because nothing is currently approved.
At a glance
| Sermorelin | Tesamorelin | |
|---|---|---|
| Mechanism | GHRH(1-29) analog — binds the pituitary GHRH receptor, stimulates endogenous GH release [1] | GHRH(1-44) analog, stabilized against enzymatic breakdown — same receptor, longer-acting molecule |
| FDA status today | Not currently approved in any form. Originally approved as Geref (two NDAs, 1990 and 1997); both discontinued for non-safety reasons. Everything sold today is compounded from bulk powder [2] | Currently FDA-approved and marketed as EGRIFTA SV (BLA022505, Theratechnologies), first approved 2010 |
| What it is approved for | Nothing, currently | Reduction of excess abdominal visceral fat in HIV-infected adults with lipodystrophy — a narrow, specific indication, explicitly not indicated for general weight loss [3] |
| Outcome-trial evidence | Ten RCTs ever indexed on PubMed; one small positive adult outcome trial (n = 19), unreplicated in 29 years [4] | Multiple modern, well-powered RCTs: a 12-month visceral-fat/cardiovascular trial (n = 60) [5], a 20-week cognition trial (n = 152) [6] |
| What it is actually used for today | Off-label, compounded, marketed for general “anti-aging” and body-composition use | On-label for HIV lipodystrophy; also studied off-label in obesity and cognitive-decline populations, but not approved for either |
The regulatory story, precisely
Sermorelin was FDA-approved twice — as Geref, an injectable, first in 1990 and again in a higher-strength formulation in 1997. Both approvals belonged to EMD Serono. Both are now listed as discontinued. The FDA’s own record on both NDAs carries a specific determination: the product was “not withdrawn for safety or effectiveness reasons” [2]. That phrase matters, because a withdrawal for safety or efficacy reasons would generally have barred the substance from being used in compounding. Sermorelin’s absence of such a withdrawal is exactly what has kept it eligible to be compounded from bulk powder today. But eligibility to be compounded is not the same thing as being approved. Every sermorelin product on the market right now, without exception, is a 503A or 503B compounded preparation made from bulk active ingredient. There is no FDA-approved sermorelin product currently sold in the United States, under any brand [2]. See the full regulatory picture for what that means for a buyer.
Tesamorelin’s story is the opposite. It is a different molecule — a stabilized analog of the full GHRH(1-44) fragment rather than sermorelin’s GHRH(1-29) fragment — and it has never lost its FDA approval. It is sold today as EGRIFTA SV, a prescription injectable, under a Biologics License Application held by Theratechnologies. But here is where people talk themselves into more than the approval actually says: EGRIFTA SV’s indication is not “growth hormone deficiency,” not “anti-aging,” and not “fat loss” in any general sense. The FDA label is specific: it is indicated for the reduction of excess abdominal fat in HIV-infected adult patients with lipodystrophy. The label explicitly states it is “not indicated for weight loss management” because it has a “weight neutral effect” — meaning it moves fat from the visceral compartment without necessarily changing the number on a scale [3]. The label also flags, in its own limitations-of-use language, that tesamorelin’s long-term cardiovascular safety has not been established. That is a real, FDA-approved drug for a real, narrow population — not a general performance or longevity product, whatever the marketing around it online implies.
Why the trial evidence is not close
This is the part of the comparison that actually should move a buying decision, and it is not subtle once you look at the raw numbers. A PubMed search for sermorelin AND randomized[tiab] returns exactly ten records, ever indexed, across more than three decades of the drug’s existence. Of those, only one is a placebo-controlled adult trial measuring outcomes a buyer would actually notice rather than a lab biomarker. It is a 1997 study of 19 people — 10 women, 9 men, ages 55 to 71 — given nightly subcutaneous sermorelin for five months [4]. It found a real, non-trivial benefit: lean body mass increased significantly, but only in the men. It also found real limits: no change in bone density in either sex, no change in sleep quality in either sex, and no body-composition benefit in women at all. The companion immune-system paper on the same 19 subjects reported GH and IGF-1 rising as expected and no adverse effects beyond transient, self-resolving hyperlipidemia [7]. That is the entire adult outcome-trial evidence base for sermorelin: one small trial, split by sex, with real but partial findings. Nobody has gone back and repeated it in the 29 years since. See our full trial-by-trial review for how thin that record really is.
Tesamorelin’s more recent literature looks different in kind, not just in size. A 2012 trial randomized 60 obese adults with reduced GH secretion to tesamorelin or placebo for a full year. It used objective imaging — CT for visceral fat, carotid ultrasound for intima-media thickness — rather than self-report. The result: visceral fat dropped by 16 cm² on tesamorelin versus rising 19 cm² on placebo (P = 0.003), carotid intima-media thickness improved (P = 0.02), CRP fell (P = 0.04), and triglycerides improved (P = 0.02), with no significant change in glucose control [5]. A separate 2012 trial gave 152 older adults — including 66 with mild cognitive impairment — tesamorelin or placebo nightly for 20 weeks, and ran a full cognitive battery. The intent-to-treat analysis showed a significant cognitive benefit (P = 0.03), sharper in the completer analysis (P = 0.002), with a specific executive-function improvement (P = 0.005) [6]. Still, 68% of the treated arm reported adverse events against 36% on placebo.
It is worth being precise about something here: neither of those two tesamorelin trials was conducted in the HIV-lipodystrophy population the drug is actually approved for. The visceral-fat trial enrolled obese adults with reduced GH secretion; the cognition trial enrolled older adults with and without mild cognitive impairment. Both are legitimate, well-run RCTs of the same approved molecule — but they represent off-label research populations, not evidence for tesamorelin’s approved use. What they do establish is that tesamorelin, as a compound, has a substantially deeper and more modern outcome-trial record than sermorelin does, even setting the approved indication aside entirely. That is the core asymmetry of this comparison: better trial evidence exists for a chemical cousin of sermorelin than exists for sermorelin itself.
What this actually means if you are choosing between them
If your interest is specifically visceral-fat reduction and you happen to be in the population tesamorelin is approved for — HIV-associated lipodystrophy — you are looking at a drug with FDA approval and a real outcome trial behind that specific use, prescribed through a normal on-label pathway. Outside that population, both compounds are used off-label, from a regulatory standpoint: tesamorelin off-label for a non-approved population, sermorelin off-label because there is no on-label use available at all anymore. The trial evidence does not close that gap. Sermorelin’s decades-old, unreplicated, sex-split n = 19 trial is a real finding, but it is a thin one to build a purchasing decision on. Whichever one you are considering, the honest framing is this: you are looking at compounds with meaningfully different regulatory footing and meaningfully different depths of evidence. They are not two interchangeable ways to say “GHRH analog.” For sermorelin sellers themselves, see every injectable seller we could verify.