The growth-hormone axis
Secretagogues, GHRH analogues and IGF-1: one approved drug, one real human dataset, and a family of models.
Covered here: CJC-1295 · Ipamorelin · Sermorelin · Tesamorelin · IGF-1 LR3
HGH peptides are not growth hormone. The compounds sold under that label are secretagogues: molecules that act on the pituitary, either at the growth-hormone-releasing hormone receptor or at the ghrelin receptor, to prompt the body to release its own growth hormone. Sermorelin and tesamorelin are GHRH analogues, CJC-1295 is a longer-acting GHRH analogue, and ipamorelin is a ghrelin-receptor agonist. Growth hormone itself is a 191-amino-acid protein and a prescription drug.
That distinction answers the comparison people usually want. Recombinant growth hormone and a secretagogue are not the same intervention: the first is an approved drug with a label, the second depends on a pituitary that can still respond. Within the secretagogue family, only two compounds carry a meaningful human record. Tesamorelin is FDA-approved. Ibutamoren, also called MK-677, has real human trials and no approval. The rest, CJC-1295 and ipamorelin among them, have been studied mostly in models.
IGF-1 LR3 is a different molecule again, a modified form of insulin-like growth factor 1, which sits downstream of growth hormone rather than upstream of it. Whether any of this is safe is not something a research market can establish on a compound’s behalf: the ones with human safety data are the ones that went through trials. Our growth-hormone review sorts the family by what has actually been published, tier by tier.
Common questions
What are HGH peptides, and what do they do?
HGH peptides is a market label for growth-hormone secretagogues, which are not growth hormone. They act on pituitary receptors, either the GHRH receptor or the ghrelin receptor, to increase release of the body’s own growth hormone. Growth hormone itself is a 191-amino-acid protein available only as a prescription drug. The two are different interventions with different evidence behind them.
What is CJC-1295?
CJC-1295 is a synthetic analogue of growth-hormone-releasing hormone, modified to resist the enzymatic clearance that limits the natural hormone to a short half-life. It acts upstream, at the GHRH receptor on the pituitary. Its published record is largely preclinical and early-phase, and it is not approved for any indication in any major jurisdiction.
Why are ipamorelin and CJC-1295 discussed together?
They act on two different receptors, the ghrelin receptor and the GHRH receptor, which is the rationale offered for pairing them. The rationale is mechanistic rather than evidential: there is no published randomised human trial of the combination, so the pairing is an inference from how each receptor behaves, not a finding. Treating a mechanism as a result is one of the recurring errors catalogued elsewhere on this site.
What is IGF-1 LR3?
IGF-1 LR3 is a modified form of insulin-like growth factor 1, a protein that sits downstream of growth hormone in the same axis. The LR3 designation refers to sequence changes intended to extend its half-life by reducing binding to carrier proteins. It is a research compound, not an approved drug, and its published record is overwhelmingly preclinical.
Which peptides increase growth hormone?
The compounds studied for this are the GHRH analogues, including sermorelin, tesamorelin and CJC-1295, and the ghrelin-receptor agonists, including ipamorelin and the non-peptide ibutamoren. Measured release of growth hormone is one endpoint. A downstream clinical outcome is a different and much harder endpoint, and far fewer of these compounds have been tested against one.
Are HGH peptides safe?
Tesamorelin has an FDA-reviewed safety file because it went through the approval process. Ibutamoren has human trial data without an approval. For most of the research secretagogues, including CJC-1295 and ipamorelin, no comparable human safety dataset has been published, and no agency has reviewed one. That is a gap in the record rather than a clean bill of health.
Read the evidence
3 pieces on this subject, every finding attributed and every gap stated.
Related topics
For research use only · Not for human or veterinary use · No compound discussed here is FDA-approved for any indication