A coastal research digest / the growth-hormone axis
Sermorelin is GHRH(1-29), the synthetic fragment studied for nudging the body's own growth-hormone tide back up.
It does not supply growth hormone. It asks the pituitary to release its own, in the natural pulses, with the body's feedback left intact. Here is what the studies measured, and where the adult data stop.
The short version
Sermorelin is a small peptide — a chain of 29 amino acids — that copies the front end of the brain's own "make growth hormone" signal, a hormone called GHRH (growth-hormone-releasing hormone). Instead of injecting growth hormone itself, sermorelin asks the pituitary gland (a pea-sized gland under the brain) to release the body's own. That release happens in natural bursts, not a steady drip, and it raises IGF-1 (a growth signal the liver makes when growth hormone rises). Sermorelin was once an approved children's medicine; it was pulled from the US market in 2008 for business reasons and is now made by compounding pharmacies. This page digests the published research.
What Is Sermorelin?
Sermorelin is GHRH(1-29)NH2 — the amidated synthetic 29-amino-acid fragment corresponding to the active amino-terminal portion of growth-hormone-releasing hormone, and the shortest fragment that retains full activity at the GHRH receptor [1]. The natural hormone is 44 amino acids long; the first 29 carry the signal. It is a pituitary growth-hormone secretagogue (a secretagogue is something that tells a gland to release its hormone), so it works one step upstream of growth hormone rather than replacing it.
Its regulatory history is often misstated, so it is worth stating plainly. Sermorelin acetate was a prescription drug approved by the FDA for evaluating and treating growth-hormone deficiency and short stature in children. It was withdrawn from the US market in 2008 for commercial reasons — not because of any safety or efficacy problem. It is no longer sold as a finished, FDA-approved product; it is now prepared by compounding pharmacies and is treated as a long-standing Category 1 bulk drug substance under the FDA's Section 503A framework (final guidance January 2025). So the accurate phrasing is "a formerly FDA-approved GHRH analog, now compounded" — never "currently FDA-approved," and never "never approved."
Sermorelin Peptide Context: GHRH(1-29) as a Research Compound
Studied as a research peptide, sermorelin is interesting because of where it acts. It binds GHRH receptors on the somatotrophs — the growth-hormone-producing cells of the anterior pituitary — and switches on the adenylate-cyclase / cAMP / PKA pathway (a common cellular "go" signal) to stimulate synthesis and pulsatile release of growth hormone [1]. Because the signal enters upstream, the body's own brakes stay on: somatostatin (the opposing "stop" hormone) and IGF-1 negative feedback continue to shape the output, so the natural pulsatile pattern is preserved rather than overridden.
That upstream position is the whole mechanistic story of the sermorelin peptide. Direct growth hormone bypasses the pituitary and the feedback loop entirely; sermorelin leans on them. A 2006 editorial framed sermorelin as a more physiologic approach to adult-onset growth-hormone insufficiency than recombinant growth hormone precisely on those grounds [4]. The fuller pharmacology — receptor signaling, the GH/IGF-1 axis, and the analog landscape — is synthesized in the 2025 Nature Reviews Endocrinology review of GHRH and its analogues [6]. The sermorelin mechanism of action is covered in depth on the research page.
Sermorelin Acetate: The Salt Form Used in Research
Sermorelin acetate is the acetate salt of the amidated GHRH(1-29) fragment — the form supplied for laboratory work. The amidation (the NH2 on the C-terminus) and the acetate counter-ion are not cosmetic: peptide stability and handling depend on them, which is why GHRH(1-29) is supplied as a lyophilized (freeze-dried) powder rather than a ready solution. The molecule carries a molecular weight near 3357.9 Da and CAS number 86168-78-7 (the acetate salt, 114466-38-5). Pharmacokinetic work in healthy men established that the peptide is rapidly cleared yet keeps growth hormone elevated for roughly three hours after a single dose, while intranasal bioavailability was only about 3-5% [3] — context that shapes how doses were spaced in research and why oral or sublingual formats are widely doubted.
What Sermorelin Has Been Studied For
The strongest human result is the historical one. In a multicenter trial of prepubertal growth-hormone-deficient children, once-daily subcutaneous GHRH(1-29) accelerated linear growth, raising first-year height velocity from about 4.1 cm/year to roughly 7-8 cm/year, without excessive IGF-1 generation [2]. That was the basis of its approved pediatric use.
Adult research has tracked the aging growth-hormone axis. In healthy older men, 14 days of subcutaneous GHRH(1-29) produced dose-related increases in 24-hour growth hormone and IGF-1; at the high dose those values no longer differed from young men's, with no change in fasting glucose [5]. That single finding — an aging axis nudged back toward a younger profile — is the anchor of the adult literature, and it is summarized on sermorelin, aging and growth hormone. The closely related stabilized analog tesamorelin has carried much of the adult cognition and body-composition work; the sermorelin vs tesamorelin page draws that line. A frank note belongs here too: anti-aging and body-composition marketing for sermorelin runs well ahead of the adult evidence, and an Annals of Internal Medicine editorial judged growth-hormone-secretagogue use for aging "not yet ready for prime time" [9]. These pages describe research findings and give no human dosing.