What is a growth hormone secretagogue?

A compound that prompts the pituitary to release its own growth hormone, rather than supplying growth hormone from outside. Every compound in this category works this way.

What is the difference between a GHRH analogue and a GHRP?

They use different receptors. GHRH analogues such as CJC-1295, Tesamorelin and Sermorelin mimic growth hormone-releasing hormone. GHRPs such as Ipamorelin, GHRP-6, GHRP-2 and Hexarelin act on the ghrelin receptor instead.

Why do researchers pair two compounds together?

Because the two pathways are independent, so engaging both produces a release pattern neither achieves alone. Pairing two compounds from the same pathway achieves less, since they compete for the same receptor.

Which is the most selective?

Ipamorelin. It was characterised as releasing growth hormone without meaningfully raising cortisol or prolactin even at very high doses, which is what distinguishes it from the earlier GHRPs.

Are any of these approved?

Tesamorelin is the only FDA-approved GHRH analogue. Sermorelin was formerly approved and later discontinued commercially. The others hold no regulatory approval, and the compounds themselves are research-grade materials only.

Research Library›Growth Hormone & Endocrine›Growth Hormone Secretagogues Explained

Category Overview

Growth Hormone Secretagogues Explained: Asking Rather Than Giving

None of these compounds are growth hormone. Every one of them is a way of asking the body to release its own — and that distinction shapes everything about how they behave.

8 min read·4 studies cited·Updated July 2026

Quick Reference

Category	GH secretagogues
Two pathways	GHRH receptor · ghrelin receptor
Key principle	Ask the pituitary, do not supply the hormone
Compounds covered	CJC-1295, Ipamorelin, Tesamorelin, GHRP-6, GHRP-2, Sermorelin, Hexarelin
Status	Research use only

The Core Idea

A secretagogue is anything that prompts a gland to secrete something. Every compound in this category works that way: none of them is growth hormone, and none supplies it. They all ask the pituitary to release its own.

Why that distinction matters, in plain language: there are two ways to get water out of a well. You can pour water in from a tanker, or you can work the pump. Supplying growth hormone directly is the tanker — the amount is whatever you poured, arriving whenever you poured it, regardless of what the body would have chosen. A secretagogue works the pump. What comes up is the body’s own supply, released through the body’s own machinery, still subject to the body’s own limits and rhythms. That last part matters: a pump cannot draw from an empty well, and the body retains its feedback controls.

This is why the literature on these compounds is preoccupied with release patterns rather than simply amounts. Growth hormone is naturally released in pulses, concentrated during deep sleep, and tissues appear to respond to that rhythm rather than to a flat level.

The Two Pathways

Every compound here reaches the pituitary through one of two receptors, and knowing which is the single most useful thing to understand about the category.

The GHRH pathway is the body’s primary instruction to release growth hormone. Sermorelin is the plain fragment of that hormone; CJC-1295 and Tesamorelin are engineered versions built to last longer.

The ghrelin pathway is entirely separate — the receptor that ghrelin, the hunger hormone, acts on. GHRP-6, GHRP-2, Hexarelin and Ipamorelin all work here.

Because the pathways are independent, research frequently pairs one from each — a GHRH analogue with a GHRP — to study what happens when both are engaged at once. Pairing two compounds from the same pathway achieves considerably less, because they compete for the same receptor.

The Family Progression

The GHRP side reads as a single story of refinement. GHRP-6 came first, in 1984, and proved the pathway existed — but it brought pronounced appetite stimulation and raised cortisol and prolactin alongside the growth hormone. GHRP-2 narrowed that. Ipamorelin narrowed it further, and was characterised as releasing growth hormone without meaningfully affecting cortisol or prolactin even at very high doses. Hexarelin is the outlier: potent, but with marked desensitisation and a separate cardiac research line through the CD36 receptor.

The GHRH side is a story about duration rather than selectivity. Sermorelin works but clears within minutes; CJC-1295 and Tesamorelin are two different engineering answers to that same problem.

Frequently Asked Questions

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

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Published References

Raun K, Hansen BS, Johansen NL, et al. “Ipamorelin, the first selective growth hormone secretagogue.” European journal of endocrinology, 1998. PubMed
Bowers CY, Momany FA, Reynolds GA, et al. “On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone.” Endocrinology, 1984. PubMed
Sigalos JT, Pastuszak AW. “The Safety and Efficacy of Growth Hormone Secretagogues.” Sexual medicine reviews, 2018. 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