What is a growth hormone secretagogue?

The growth hormone axis works in two steps. The hypothalamus releases GHRH (growth-hormone-releasing hormone), which tells the pituitary gland to release growth hormone (GH) into the blood. GH then acts on the liver and other tissues, partly through IGF-1.

A secretagogue is simply something that triggers a gland to secrete. So a growth hormone secretagogue prompts your own pituitary to release its own GH. That is the key distinction from injecting recombinant human GH (rhGH) directly: a secretagogue works upstream and, in theory, preserves the body's natural pulsing rhythm and its own feedback brakes. Whether that theoretical advantage translates into a real-world benefit in healthy people is a separate question, and the answer is mostly "not clearly."

Almost every GH secretagogue falls into one of two groups, defined by which receptor it acts on.

1. GHRH analogues. These copy the natural GHRH signal at the GHRH receptor. They include sermorelin, CJC-1295 and tesamorelin. Tesamorelin is the one with a genuine regulatory approval (for HIV-associated lipodystrophy), which makes it the clearest evidence anchor in the class.

2. Ghrelin mimetics / GHRPs / GHS-receptor agonists. These act on a different target, the growth-hormone-secretagogue receptor (GHS-R), the same receptor the hunger hormone ghrelin uses. They include the peptides ipamorelin and hexarelin, and the orally active small molecule [MK-677 / ibutamoren](/peptides/mk-677). Confusingly, the whole class takes its name from this second receptor, but the GHRH analogues belong to the class too.

Because the two families work through separate receptors, they can be combined, and a common pattern is to pair a GHRH analogue (such as CJC-1295) with a GHRP (such as ipamorelin). The rationale is that the GHRH analogue raises the amount of GH released per pulse while the GHRP both amplifies that pulse and partly suppresses somatostatin, the body's natural "stop" signal. In short-term studies the combination produces a larger acute GH release than either alone.

A bigger GH spike on a blood test is not the same as a meaningful clinical benefit, however. We describe this physiology because it is what the literature reports, not as a protocol: this site gives no dosing or stacking instructions. See how we grade evidence for why an acute hormone bump rarely earns a strong rating.

Be sceptical of strong claims here. Most marketing leans on preclinical (animal or cell) data, on studies in people with a genuine deficiency, or on the fact that a compound can acutely raise GH, then implies benefits for muscle, fat loss, sleep, recovery or anti-ageing in healthy adults. Those benefits are largely unproven in that population.

The class also has real safety signals worth naming. MK-677 reliably raises blood sugar and IGF-1 and can cause fluid retention, and a large trial of it in older adults was stopped over concerns including a heart-failure imbalance. More broadly, chronically elevated GH/IGF-1 is not automatically desirable: acromegaly, the disease of GH excess, causes serious harm, and IGF-1 signalling is biologically linked to growth that you may not want amplified. "More GH" is a means, not a goal.

Many of these compounds are sold as research chemicals with no human safety data behind a given product. We grade each peptide on its own human evidence, not on the promise of the class.

For sport, this entire class is banned. The World Anti-Doping Agency prohibits growth hormone, GH secretagogues, GHRH analogues, GHRPs and GHS-R agonists at all times, in and out of competition. Athletes who use any of them risk a doping violation. If you compete under any anti-doping code, treat the whole class as off-limits.

Legally, the picture is mixed. Tesamorelin is an approved prescription medicine in some regions; the rest are generally not approved for the uses they are marketed for and are frequently sold "for research use only." That label does not make a product safe, legal to supply for human use, or quality-controlled. For the UK specifics, see are peptides legal in the UK? and our legality overview.