Sermorelin

Sermorelin is GHRH(1-29), the opening 29 amino acids of growth-hormone-releasing hormone and the shortest fragment that keeps full biological activity, studied for its ability to drive pulsatile growth-hormone release through the pituitary GHRH receptor.

What it is

Sermorelin is a synthetic 29-amino-acid peptide corresponding to the biologically active 1-29 N-terminal fragment of endogenous human growth-hormone-releasing hormone (GHRH, also written GRF). Native GHRH is a 44-residue hypothalamic peptide, but the first 29 residues are sufficient to retain essentially full potency at the GHRH receptor, which is why GHRH(1-29) became the reference research analogue. It has a molecular formula of C₁₄₉H₂₄₆N₄₄O₄₂S and a molecular weight of about 3357.9 Da (Wikipedia / PubChem).

Historically, sermorelin acetate was developed as an FDA-approved agent (Geref) for diagnosing and treating idiopathic growth-hormone deficiency in children before its withdrawal from the market in 2008 for commercial reasons. That regulatory history left behind an unusually deep set of published human data for a growth-hormone-axis peptide, making it one of the longest-studied GHRH compounds in the literature. Supplied strictly for laboratory research use only, not for human or veterinary use.

How it works

Sermorelin binds the GHRH receptor, a class B G-protein-coupled receptor expressed on the somatotroph cells of the anterior pituitary. Receptor engagement activates adenylate cyclase through G_s, raising intracellular cyclic AMP, which in turn promotes synthesis and pulsatile secretion of endogenous growth hormone (GH). Because the signal originates at the pituitary rather than bypassing it, the released GH remains subject to the body's own regulatory brakes: rising GH and downstream IGF-1 feed back to the hypothalamus and pituitary, and somatostatin tone continues to gate release.

This upstream mechanism is the central reason sermorelin is studied as a distinct approach from recombinant GH. Rather than delivering a fixed exogenous GH load, it amplifies the animal's or subject's own GH-IGF-1 axis while preserving negative feedback, so the pulsatile rhythm of secretion is largely maintained and supraphysiological IGF-1 excursions are less likely. It differs from the ghrelin-mimetic GH secretagogues (such as ipamorelin), which act on a separate receptor, the GHSR, and are sometimes paired with GHRH analogues to recruit both release pathways at once.

What the research shows

The strongest human data come from pediatric growth-hormone-deficiency work and from GHRH(1-29) trials in older adults. In prepubertal GH-deficient children, once-daily subcutaneous GHRH(1-29) at 30 mcg/kg at bedtime raised mean height velocity from roughly 4.1 cm/year at baseline to about 8.0 cm/year at 6 months, with about 74% classed as good responders and velocity of about 7.2 cm/year sustained at 12 months. As a diagnostic agent, a single 1 mcg/kg intravenous dose produces a rapid, relatively GH-specific provocative response used to probe pituitary reserve. In age-advanced adults, 16 weeks of nightly [Nle²⁷]GHRH(1-29) at 10 mcg/kg significantly raised nocturnal integrated GH and serum IGF-1.

Side Effects

Unlike many research peptides, sermorelin has real human safety data because it was once an approved drug: Geref (sermorelin acetate), used both as a diagnostic agent for growth hormone secretion and as a therapy for pediatric growth hormone deficiency. Across those clinical uses it was generally well tolerated, with most reported effects being mild, local, and transient. The single most common finding was a reaction at the injection site. The table below summarizes effects documented in the drug label and in the clinical literature.

Overall, sermorelin showed a favorable tolerability profile in its clinical history, with adverse effects that were usually mild and short-lived. Reactions at the injection site, such as pain, swelling, or redness, are the most frequently reported effect and account for the bulk of what was seen in trials.

At a glance

Dosing

Sermorelin (GHRH 1-29) has genuine label dosing from its time as a prescription product. In the United States it was marketed by Serono as Geref for treating idiopathic growth hormone deficiency (GHD) in children (NDA 20-443, approved 26 September 1997) and as Geref Diagnostic for pituitary growth hormone testing (NDA 19-863, approved 28 December 1990). The figures below are the documented therapeutic and diagnostic regimens, presented as historical label and study doses rather than instructions.

EMD Serono discontinued both Geref products in 2008, and the FDA withdrew approval of the two applications effective 18 June 2009, later confirming the removals were for business reasons, not safety or effectiveness. Sermorelin is no longer an FDA-approved medicine in the United States, so the doses above are documented for reference and laboratory research use only, not as clinical guidance.

Preparing it

The vial ships as a lyophilized powder and is reconstituted with bacteriostatic water (or sterile water for single-session work) before use. Choose a diluent volume that gives a concentration convenient to read on a U-100 syringe, and store the reconstituted solution refrigerated at 2-8 C. See reconstitution for the step-by-step method and the concentration formula for working out how much diluent to add.

Where to go next

Last updated on July 3, 2026