GH Secretagogues Explained: Ipamorelin, CJC-1295, Tesamorelin & HGH Fragment

The short version: A growth-hormone (GH) secretagogue is a compound studied for its ability to act on the body’s own GH signalling axis, rather than being GH itself. Researchers group these peptides by which “switch” in that axis they’re investigated against.

What “secretagogue” actually means

The word looks technical, but it breaks down simply. A secretagogue is anything studied for its role in prompting a gland to release a substance it already makes. In this case, the substance is growth hormone, and the gland is the pituitary.

So a GH secretagogue is not growth hormone. It is a separate class of compounds investigated in research models for how they interact with the signalling pathway that governs the body’s own GH release.

Think of the GH axis like a thermostat-and-furnace system. The furnace (the pituitary) is what produces the heat (GH). A secretagogue is studied as something that acts on the thermostat and its wiring, rather than being the heat poured in from outside.

How that differs from exogenous GH

This is the core distinction in the literature. Exogenous GH refers to growth hormone introduced from an outside source: the finished molecule itself. A secretagogue, by contrast, is studied for its interaction with the upstream system that governs how much GH the pituitary releases on its own.

That difference matters to researchers because the two concepts sit at different points in the axis. One is the end product; the other is investigated against the control mechanism. The pulsatile, self-regulating nature of the body’s own axis is precisely why the secretagogue concept is studied as a distinct research category.

The single idea to hold onto: a secretagogue is studied for its role in the GH signalling axis, while exogenous GH is the molecule itself. Same axis, very different research concept.

Two families researchers talk about

Within the secretagogue label, the literature usually sorts compounds into two groups based on which receptor pathway they are investigated against.

GHRH analogues. These are studied as structural relatives of growth-hormone-releasing hormone — the body’s natural “release” signal. CJC-1295 and Tesamorelin are discussed here.

GHRPs / ghrelin-receptor agonists. These are studied against a separate receptor (the ghrelin/GHS receptor) that the axis also responds to. Ipamorelin sits in this group. Because the two families are investigated against different switches, researchers often discuss them side by side.

HGH Fragment 176-191 is the odd one out: it is the last 16 amino acids of the 191-amino-acid GH molecule rather than a secretagogue acting upstream, so it is profiled here for context within the same group of compounds rather than as a true secretagogue.

A quick profile of each

Ipamorelin

Ipamorelin is investigated against the ghrelin/GHS receptor. In the research literature it is frequently described as one of the more selective peptides in its family, which is part of why it appears so often in comparative studies.

CJC-1295 (No DAC)

CJC-1295 is studied as a GHRH analogue. The “No DAC” variant lacks the drug-affinity-complex modification, and researchers investigate it for a shorter, more pulse-like activity profile than the DAC-bearing version.

Tesamorelin

Tesamorelin is a stabilised GHRH analogue and the most thoroughly documented compound in this group. That depth of published characterisation is why it often serves as a reference point in the GHRH-analogue literature. It’s also the only one of the four that’s an approved drug. The FDA approved it as Egrifta, for one narrow use: reducing excess belly fat in adults with HIV who have lipodystrophy.

HGH Fragment 176-191

HGH Fragment 176-191 is not a secretagogue. Full-length GH is 191 amino acids long, and this fragment is the last 16 of them, positions 176 to 191. It is studied on its own terms, separate from the upstream-acting peptides above.

Why researchers group them this way

Sorting these compounds by receptor pathway keeps the research tidy. GHRH analogues and ghrelin-receptor agonists are investigated against different switches on the same axis, so grouping by mechanism — rather than by name alone — makes it easier to read across studies and understand why one peptide is discussed alongside another.

It also clarifies where the GH fragment fits: outside the secretagogue families entirely, which is exactly why we flag it separately rather than lumping it in.

Why sport bans all four

All four are on the World Anti-Doping Agency’s 2026 Prohibited List, under S2. Ipamorelin, CJC-1295 and tesamorelin are listed as growth hormone releasing factors (S2.2.4). hGH 176-191 is named as a growth hormone fragment (S2.2.3). If you compete in tested sport, treat all four as off limits.

Where the evidence stops

• Only tesamorelin is an approved drug, and only for one use. The side effects its label lists most often are joint pain, redness and itching where it was injected, pain in the arms or legs, swelling, and muscle pain.
• Ipamorelin’s “selective” tag comes from animal work. The 1998 paper that named it tested it in rat cells, rats and pigs.
• The CJC-1295 human data is short and narrow. The study we link gave the long-acting (DAC) version to healthy adults for up to 49 days and measured hormone levels. It wasn’t built to show anything past those levels.
• We didn’t find a published trial of hGH 176-191 itself when we searched PubMed, so we don’t cite one.

Handling notes

All four are supplied as research-grade material for laboratory work only. As with any lyophilised peptide, reconstitution, storage and labelling follow standard laboratory procedure.

Where JP fits

JP Research stocks this family as research-grade material: Ipamorelin 5mg, CJC-1295 with DAC 10mg, the CJC-1295 + Ipamorelin blend, Tesamorelin 2mg and HGH Fragment 176-191 5mg. The No-DAC version of CJC-1295 is out of stock at the moment. You can also browse the full catalogue for specifications.

Where we hold an independent lab report for a product, it’s on our lab reports wall and the product page says so. Where we don’t, the product page says “No report held”.

Sources

• World Anti-Doping Agency: Prohibited List 2026 (S2.2.3 growth hormone fragments; S2.2.4 growth hormone releasing factors)
• FDA label via DailyMed: Egrifta SV (tesamorelin) for injection, prescribing information
• FDA label via DailyMed: Norditropin (somatropin), which describes GH as 191 amino acids
• Raun et al.: Ipamorelin, the first selective growth hormone secretagogue (Eur J Endocrinol, 1998)
• Teichman 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 (J Clin Endocrinol Metab, 2006)

Plain-English guides on Peptide Carl: Ipamorelin and CJC-1295. Carl is the free education site we run.