The first twenty-nine amino acids of growth hormone-releasing hormone — the fragment that carries essentially all of the molecule’s receptor activity. It is the unmodified baseline GHRH analogue.

How is Sermorelin related to CJC-1295?

CJC-1295 is an engineered version of the same twenty-nine-amino-acid fragment, modified to resist the enzymes that would otherwise break it down quickly. Sermorelin is that fragment without the modifications.

Why do the newer GHRH analogues exist if Sermorelin already worked?

Because Sermorelin’s half-life is measured in minutes. Both CJC-1295 and Tesamorelin are attempts to solve that specific problem — one by modifying the shortened fragment, the other by stabilising the full-length hormone.

Is Sermorelin FDA-approved?

It was formerly approved and marketed as Geref for growth hormone deficiency assessment and treatment, and was later discontinued commercially. It does not hold current approval as a marketed product, and the distinction between "was approved" and "is approved" is worth keeping in mind when reading claims about it.

Research Library›Growth Hormone & Endocrine›Sermorelin

GHRH(1–29) Fragment

Sermorelin: The Original Fragment Everything Else Was Built From

The first twenty-nine amino acids of growth hormone-releasing hormone — the shortest piece that still works. CJC-1295 and Tesamorelin are both engineered versions of this molecule.

6 min read·4 studies cited·Updated July 2026

Evidence level

Approved as a medicine in at least one jurisdiction

Formerly FDA-approved (Geref); discontinued commercially

What this level means

Quick Reference

Class	GHRH analogue
Structure	GHRH(1–29) — the active fragment
Relationship	The unmodified parent of CJC-1295
Half-life	Short — minutes
Regulatory	Formerly FDA-approved (Geref); discontinued

What Is Sermorelin?

Sermorelin is the first twenty-nine amino acids of growth hormone-releasing hormone. Natural GHRH is forty-four amino acids long, and researchers established that the opening twenty-nine carry essentially all of the receptor activity — the remaining fifteen can be removed without losing the signal.

That makes Sermorelin the baseline GHRH analogue: the natural signal, trimmed to its working part, and otherwise unmodified.

Why trimming works, in plain language: a key has a long shaft and a jagged working end. The jagged end does the actual work; much of the rest is handle. Researchers found they could cut a GHRH molecule down to its first twenty-nine residues and it still turned the lock. Sermorelin is that cut-down key — same shape where it matters, less metal.

The Problem It Left Behind

Sermorelin works, but it does not last. Its half-life is measured in minutes — the body clears it very quickly, which is true of natural GHRH as well. That brevity is the specific problem the next generation of compounds set out to solve.

Tesamorelin took the full forty-four-amino-acid sequence and added a stabilising modification, producing a molecule that resists breakdown while staying close to the natural hormone. CJC-1295 took the twenty-nine-residue fragment — Sermorelin’s structure — and modified it to resist the enzymes that would otherwise degrade it. The original CJC-1295 went further, adding a Drug Affinity Complex that extended its duration dramatically; the "No DAC" version omits that.

So the GHRH branch of this family is really one molecule and a series of attempts to make it survive longer. Sermorelin is the honest starting point of that sequence.

A Regulatory History Worth Reading Carefully

Sermorelin has an unusual status among research peptides: it was formerly FDA-approved, marketed as Geref for the assessment and treatment of growth hormone deficiency in children.

It was subsequently discontinued commercially. Withdrawal of that kind is not necessarily a safety judgement — products are pulled for commercial reasons, shifts in clinical practice, or the arrival of alternatives — but the practical position today is that Sermorelin does not hold current approval as a marketed product in the way Tesamorelin does.

This distinction matters when reading claims about it. "Was FDA-approved" and "is FDA-approved" are different statements, and the first is frequently used to imply the second.

Frequently Asked Questions

Compiled by the Southern Pacific Labs research team. Last updated July 2026.

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Published References

Prakash A, Goa KL. “Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency.” BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy, 1999. PubMed
Teichman SL, Neale A, Lawrence B, et al. “Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults.” The Journal of clinical endocrinology and metabolism, 2006. PubMed
Walker RF. “Sermorelin: a better approach to management of adult-onset growth hormone insufficiency?” Clinical interventions in aging, 2006. PubMed
Sigalos JT, Pastuszak AW. “The Safety and Efficacy of Growth Hormone Secretagogues.” Sexual medicine reviews, 2018. PubMed