Sermorelin is the GHRH(1-29) peptide studied for growth hormone, IGF-1, and body composition.

The short version

Sermorelin is a lab-made copy of the first 29 building blocks of GHRH (the brain's own "make growth hormone" signal). Given as a shot, it tells the pituitary — a gland at the base of the brain — to release the body's own growth hormone (GH) in natural bursts, which then raises IGF-1 (a growth signal the liver makes when GH rises). It does not replace growth hormone; it asks the gland to make its own. It was once an FDA-approved drug for short children, was pulled from the US market in 2008 for business reasons (not safety), and is now made by compounding pharmacies. These pages are a research digest, not dosing advice — they describe what studies measured, not what anyone should take.

What is sermorelin?

Sermorelin (sermorelin acetate) is a synthetic 29-amino-acid peptide that copies the amino-terminal 1-29 fragment of human growth hormone-releasing hormone — the natural 44-residue hypothalamic hormone GHRH (the signal the brain sends to start GH production) ^[15]. GHRH(1-29) is the shortest fragment that keeps full activity at the GHRH receptor, which is why the larger molecule is unnecessary. Its molecular weight is 3,357.9 Da; CAS 86168-78-7; molecular formula C149H246N44O42S. It also goes by GRF(1-29) and GRF(1-29)NH2 — the amide group at the C-terminus matters for activity.

Sermorelin is a secretagogue — something that tells a gland to release its own hormone — not a hormone replacement. That distinction is the whole point of the molecule. Because it acts upstream on the pituitary rather than supplying growth hormone from outside, the body's own feedback brakes (somatostatin, the opposing "stop" hormone, and IGF-1) stay intact, so GH is released in its natural pulsatile pattern — in bursts, not a steady drip ^[4][15]. Endogenous GHRH-driven GH secretion declines with age, which is the rationale behind much of the adult research described on this site ^[2].

Sermorelin mechanism of action

Sermorelin binds the GHRH receptor (GHRH-R, a class B G-protein-coupled receptor) on the growth-hormone-producing cells of the anterior pituitary, the somatotrophs ^[15]. Receptor activation drives the Gs / adenylate cyclase / cAMP / protein kinase A pathway, which raises GH gene transcription and prompts synthesis and pulsatile release of growth hormone. The receptor's activation also has a trophic effect — it supports somatotroph proliferation — which is part of why a secretagogue can sustain output rather than deplete it ^[15].

Circulating GH then signals the liver to produce IGF-1, the messenger that carries out much of GH's downstream action. The key structural point: because the trigger is upstream, somatostatin and IGF-1 negative feedback continue to govern output, so the dose cannot simply override the axis the way injected GH can ^[4][15]. In healthy older men, this mechanism produced dose-related increases in 24-hour GH and IGF-1 over 14 days, with high-dose values no longer differing from those of young men, and no effect on fasting glucose ^[2]. The full research findings on sermorelin trace this pathway from receptor to IGF-1.

Sermorelin as a GHRH peptide

As a sermorelin peptide, the molecule belongs to the GHRH-analog class: synthetic peptides built on the GHRH(1-29) backbone that act at the GHRH receptor. This is a different mechanism from the growth-hormone-releasing peptides (GHRPs) such as ipamorelin or GHRP-6, which act on the ghrelin/GHS receptor ^[15]. Sermorelin is the native, short-lived 1-29 sequence; stabilized relatives extend its duration through structural changes — a D-Ala2 substitution and serum-albumin-binding chemistry underlie longer-acting GHRH analogs, and tesamorelin is the stabilized analog that carries most of the research findings on sermorelin's body-composition class ^[11]. The dose-responsiveness of the GHRH(1-29) backbone has been confirmed across intravenous, subcutaneous, and intranasal routes in healthy men ^[14].

What the research reports on sermorelin benefits

Reframed as "what the studies actually measured," the sermorelin benefits documented in controlled work are specific and bounded. For its historical approved use — accelerating growth in growth-hormone-deficient children — once-daily subcutaneous GHRH(1-29) raised first-year height velocity from about 4.1 cm/year to roughly 7-8 cm/year, without excessive IGF-1 generation ^[1]. In healthy older men, GHRH(1-29) reversed the age-related decline in GH and IGF-1 at the higher dose ^[2]. A GHRH-analog trial in older adults reported a favorable effect on cognition alongside a 117% rise in IGF-1 and a 7.4% reduction in percent body fat over 20 weeks ^[6]. What is not established is long-term adult "anti-aging" efficacy: an Annals of Internal Medicine editorial judged growth-hormone-secretagogue use for aging "not yet ready for prime time" ^[5]. Read how sermorelin works against what it has and has not been shown to do.

What does sermorelin do to the body?

Sermorelin raises the body's own growth hormone and, through it, IGF-1, while leaving the natural feedback loops in place ^[2][4]. Its action is confined to the GH/IGF-1 (somatotropic) axis — it is not a sex-hormone, thyroid, or insulin therapy, though GH does influence glucose handling, and a related GHRH analog altered both GH pulsatility and insulin sensitivity in healthy men ^[13]. An editorial argues that, because it preserves pulsatile GH release and pituitary feedback, sermorelin may be a more physiologic approach to adult-onset GH insufficiency than recombinant growth hormone ^[4]. What it does not do, on the current evidence, is act as a proven fat-loss or muscle-building agent in healthy adults — the body-composition signal in this drug class comes largely from the stabilized analog tesamorelin, which reduced visceral fat versus placebo in dedicated trials ^[7]. See sermorelin vs tesamorelin for that distinction.

Where sermorelin stands now

Sermorelin's regulatory history is frequently misstated, so it is worth setting down plainly. It was an FDA-approved prescription drug for evaluating and treating idiopathic growth hormone deficiency / short stature in children, and it was withdrawn from the US market in 2008 for commercial reasons — not because of any safety or efficacy problem ^[1]. It is not a banned or unsafe substance and it is not a controlled substance; it is simply no longer sold as a branded finished product. Today it is prepared by compounding pharmacies and is treated as a long-standing Category 1 bulk drug substance under FDA's interim Section 503A policy, with final guidance issued in January 2025. Separately, growth-hormone secretagogues — including GHRH analogs — are prohibited in sport by WADA. The material these pages discuss is research-grade sermorelin supplied for laboratory research, not a compounded prescription, which is why nothing here is framed as a medicine to self-administer. Every claim above is traceable to its source in the references and citations.