Research broadsheet / GHRH(1-29)
Sermorelin is the GHRH(1-29) secretagogue, read here through what its studies in men and IGF-1 actually measured.
A carved digest of the mechanism, the dose-response data in older men, the short half-life, and the line where adult anti-aging marketing outruns the evidence — every figure cited to the study that produced it.
The short version
Sermorelin is a small synthetic copy of the brain's own "make growth hormone" signal. The body's hypothalamus releases a hormone called GHRH (growth hormone-releasing hormone) that tells the pituitary gland to put out growth hormone (GH); sermorelin is the first 29 amino acids of that hormone — the shortest piece that still works fully. It is a secretagogue (something that tells a gland to release its own hormone), so it prompts your pituitary to make GH in natural bursts rather than supplying GH from outside. In older men, it raised GH and IGF-1 — a growth signal the liver makes when GH rises — back toward youthful levels [2]. This page covers what sermorelin is, what it does in the body, and where the research stops.
Sermorelin Peptide: GHRH(1-29) and the Somatotropic Axis
The sermorelin peptide is the amidated 1-29 N-terminal fragment of growth hormone-releasing hormone — the shortest fragment of the 44-residue parent hormone that keeps full activity at the GHRH receptor [1]. It is a 29-amino-acid chain, molecular weight 3,357.9 Da, supplied as the acetate salt and known in the literature as GRF(1-29) or GHRH(1-29)NH2.
Its job is upstream. Rather than delivering growth hormone into the body, sermorelin binds the GHRH receptor on the pituitary's growth-hormone-producing cells (somatotrophs) and tells them to synthesize and release the body's own GH in its natural pulsatile pattern — bursts, not a steady drip [4]. Because the signal still has to pass through the pituitary, the body's own brakes stay on: somatostatin and IGF-1 feedback continue to regulate how much GH actually comes out [12]. That is the somatotropic axis — hypothalamus to pituitary to liver — and sermorelin acts at the top of it.
The axis weakens with age. Using a GHRH-receptor antagonist in healthy men, one study found nocturnal GH about 30% lower in elderly than young men and traced the decline to reduced endogenous hypothalamic GHRH output — a relative GHRH deficiency of aging [9]. That is the physiologic gap a GHRH analog is studied against.
What the older-men literature actually measured
The clearest adult result is a reversal. In healthy old men (mean age 68), subcutaneous GHRH(1-29) at 0.5 mg and 1 mg twice daily for 14 days produced dose-related increases in 24-hour GH and IGF-1; after the high dose, their GH and IGF-1 parameters no longer differed from those of young men, with no change in fasting glucose [2]. The age-related decline was, for the duration of the study, undone.
The pharmacology is brisk. In 30 healthy men, intravenous GHRH(1-29)NH2 triggered GH release at doses as low as 0.25 mcg/kg, peaking at 1-2 mcg/kg, and despite rapid clearance the GH rise lasted about 3 hours; given intranasally, only 3-5% of the dose reached circulation [3]. The native peptide is gone from plasma in minutes but its downstream effect — a GH pulse — outlasts it.
The pediatric record is where sermorelin earned its approval. In a multicenter trial of prepubertal growth-hormone-deficient children, once-daily subcutaneous sermorelin 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 [1]. The full account is on the sermorelin mechanism of action page.
What Is Sermorelin?
What is sermorelin?
Sermorelin is the amidated synthetic 29-amino-acid fragment of growth hormone-releasing hormone — the shortest piece that retains full activity at the GHRH receptor — a pituitary GH secretagogue that stimulates the body's own pulsatile GH release [1]. It is research-grade material here, summarized as published science, not a medicine to self-administer.
What does sermorelin do to the body?
It binds GHRH receptors on anterior-pituitary somatotrophs and raises cAMP through the Gs/adenylate-cyclase/PKA pathway, driving synthesis and pulsatile release of growth hormone, which in turn raises liver-made IGF-1 — all while somatostatin and IGF-1 feedback stay intact [4][12].
Will sermorelin raise my IGF-1 levels?
In healthy older men, subcutaneous GHRH(1-29) at 0.5-1 mg twice daily for 14 days produced dose-related increases in 24-hour GH and IGF-1, with high-dose values no longer differing from young men [2]. The IGF-1 response is the axis-level readout of the GH pulses sermorelin stimulates.
What is sermorelin used for?
It was FDA-approved (NDA 020443) for evaluation and treatment of idiopathic growth hormone deficiency and short stature in children, then withdrawn from the US market in 2008 for commercial reasons; it is also studied in adult GH-axis research covering aging, cognition, sleep, and body composition [1][5]. It is now prepared by compounding pharmacies and is not a currently-marketed FDA-approved finished drug.
A formerly-approved peptide, often misdescribed
Sermorelin's status is routinely stated wrong, so it is worth carving out plainly. Sermorelin acetate was an FDA-approved prescription drug (NDA 020443) for growth hormone deficiency in children, and it was withdrawn from the US market in 2008 for commercial reasons — not for any safety or efficacy failure. It was never "banned" and never "unapproved"; it simply stopped being sold as a branded product and is now prepared by compounding pharmacies under FDA's Section 503A framework.
The adult anti-aging story is the other half of the honesty. Sermorelin is widely promoted for anti-aging and body-composition benefits, but an Annals of Internal Medicine editorial judged the use of growth hormone secretagogues to prevent or treat the effects of aging "not yet ready for prime time" [5]. This site reports the findings; it does not endorse that use. For the safety picture, see sermorelin side effects; for how it differs from the GHRP class, see sermorelin vs ipamorelin; and for short, cited answers to the most-asked questions, see the frequently asked questions about sermorelin.