Sermorelin

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Snapshot

Chemistry and make-up

Sermorelin is the first 29 amino acids of native human GHRH, unmodified, with a C-terminal amide. Those 29 residues carry essentially the full biological potency of the 44-residue parent hormone, which is why the fragment is used rather than full-length GHRH. It is a linear peptide, no cysteine, no disulfide, no lipid, no albumin linker.

The single feature that dominates its chemistry and its QC identity is methionine at position 27. That methionine:

• makes sermorelin the only molecule in this cluster whose formula contains sulfur (the “S” in C149H246N44O42S), which is a clean fingerprint against its lookalikes; and
• is oxidation-sensitive, a real degradation route that the engineered analogues were designed to remove.

How it differs from CJC-1295 (native vs substituted). CJC-1295 without DAC (modified GRF(1-29)) is sermorelin with four deliberate substitutions, at positions 2 (Ala->D-Ala), 8 (Asn->Gln), 15 (Gly->Ala) and 27 (Met->Leu). Sermorelin keeps the native residue at every one of those positions. Consequences:

• Sermorelin is cleaved quickly by DPP-4 at the N-terminus (no protective D-Ala2), giving a very short plasma half-life of roughly 10 minutes [A/B]. The substituted analogues resist DPP-4 and last longer.
• Because sermorelin keeps Met27 and the analogues use Leu27, sermorelin is ~10 Da lighter than modified GRF(1-29) (3357.9 vs 3367.9) and contains sulfur, whereas modified GRF(1-29) does not. That is the definitive way to tell them apart on a CoA.

Do not confuse sermorelin with tesamorelin, which is GHRH(1-44) carrying an N-terminal trans-3-hexenoyl group (much larger, ~5136 g/mol, formula C221H366N72O67S), a different and FDA-approved molecule.

What it is studied for (evidence)

• Mechanism: binds the pituitary GHRH receptor and stimulates the somatotrophs to release stored GH in a physiological, pulsatile pattern; it acts upstream of GH rather than replacing it [A/B].
• Established (good evidence): sermorelin has the strongest regulatory pedigree of this whole cluster. It was an FDA-approved medicine (Geref, approved 1997) used both to treat paediatric GH deficiency and, as Geref Diagnostic, to test pituitary GH reserve. Its ability to provoke GH release in humans is well established from that clinical era [B]. As a diagnostic it was valued for a rapid, relatively specific GH response with fewer false positives than some alternatives [B/D].
• Emerging / thin / preclinical only: modern “anti-ageing”, body-composition, sleep and wellness claims rest largely on clinic marketing and small or uncontrolled reports [D], not on the approval-grade evidence that supported the original diagnostic/paediatric indications.
• Marketing claims vs data: telehealth and compounding-clinic pages routinely present sermorelin as a proven anti-ageing and fat-loss therapy in healthy adults. The robust human evidence is for GH-axis stimulation and diagnosis, not for those lifestyle outcomes. Keep the two apart.
• Human clinical status: formerly approved (Geref), withdrawn from the US market in 2008 for commercial/manufacturing reasons, not safety or efficacy [B]. Now supplied in the US only as a compounded prescription product; elsewhere it is handled as research-use-only material outside of any medicine.

Handling, format and stability

Supplied lyophilised as the acetate salt, reconstituted with bacteriostatic or sterile water for research handling (no dosing guidance here). Store lyophilised cold and protected from light; reconstituted peptide is markedly less stable and cold-chain dependent. The stability watch-point unique to sermorelin is methionine-27 oxidation: light, heat and oxygen exposure can oxidise Met27 to the sulfoxide, creating a +16 Da related impurity that a good MS/HPLC method should resolve. This liability is precisely what the Met->Leu swap in modified GRF(1-29) removes, so sermorelin is the more oxidation-sensitive of the pair.

Regulatory and trade status

• UK/EU: no current marketing authorisation as a medicine; supplied as research-use-only material. Because it genuinely was a medicine, marketing it with therapeutic claims is especially likely to trigger “medicinal product by presentation” and MHRA attention, so keep listings strictly research-use.
• US: previously FDA-approved as Geref (sermorelin acetate); the Federal Register recorded that Geref was not withdrawn for reasons of safety or effectiveness (2013 determination), which keeps a pathway open for compounding [B]. Currently available only via prescription compounding, not as a stocked FDA-approved product.
• WADA (sport): sermorelin is named on the Prohibited List under S2.2 (Growth Hormone, its fragments and releasing factors) as a GHRH analogue, prohibited at all times [B].
• Customs / labelling: identity confusion with CJC-1295 (no-DAC) and tesamorelin is the main trade and QC risk.

Sources

• [B] Federal Register, “Determination That GEREF (Sermorelin Acetate) Injection … Not Withdrawn for Reasons of Safety or Effectiveness”, 2013 — https://www.federalregister.gov/documents/2013/03/04/2013-04827/determination-that-geref-sermorelin-acetate-injection-05-milligrams-basevial-and-10-milligrams
• [B] WADA 2026 Prohibited List, S2.2 (GHRH and analogues, sermorelin named) — https://www.wada-ama.org/en/prohibited-list
• [B] PubChem CID 16132413 (formula C149H246N44O42S, MW 3357.9) — https://pubchem.ncbi.nlm.nih.gov/compound/16132413
• [A/B] Sermorelin overview (mechanism, ~10 min half-life, GHRH(1-29)) — https://www.sciencedirect.com/topics/medicine-and-dentistry/sermorelin
• [D] Telehealth/clinic explainers (Geref history, diagnostic use, anti-ageing marketing) — used as leads only, dosing and lifestyle claims not adopted — e.g. https://www.peptides.org/sermorelin/

Plain summary

Sermorelin is native human GHRH(1-29), the genuine hormone fragment, and it once was an approved medicine (Geref) for diagnosing and treating growth hormone deficiency before being pulled from the US market in 2008 for commercial, not safety, reasons. It is the parent that CJC-1295 without DAC modifies: sermorelin keeps all four native residues, so it is broken down within about 10 minutes and, uniquely in this group, still contains a sulfur-bearing methionine at position 27. That methionine is both its identity fingerprint (it makes sermorelin ~10 Da lighter than and sulfur-positive versus modified GRF(1-29)) and its main stability weakness, so any CoA must prove the molecule by observed mass plus the sulfur signature, not by name alone.

For laboratory and research use only (RUO). Not for human or veterinary use, not for consumption, and not a medicine. Information is a research summary, not medical advice, and contains no dosing guidance.

For laboratory research use only. Not for human or veterinary use, not for consumption, and not a medicine. This is a research summary, not medical advice, and contains no dosing guidance.