Six residues, and a strong signal
Hexarelin is a six-amino-acid synthetic peptide acting at the ghrelin receptor. In the studies that established the class it produced a pronounced growth hormone response, which is what made it interesting in the first place.
It also drew attention for reported cardiac effects independent of growth hormone, which opened a separate line of research that never fully developed.
Chain length is part of what made this work possible at all. A short synthetic sequence is cheap to make, quick to characterise and stable enough to handle, whereas the natural ligand at this receptor is a larger lipid-modified peptide that is considerably more awkward on every one of those counts. Establishing that six residues were enough opened the whole field.
Selectivity, and the problem it solved
Alongside growth hormone, hexarelin raises cortisol and prolactin. Those are separate hormonal axes, and moving them was not the intention. Desensitisation with continued exposure was also reported.
Ipamorelin was developed in direct response to exactly this. It acts at the same receptor and was designed to produce the growth hormone response without the cortisol and prolactin rise. That is the whole reason the newer compound exists.
Desensitisation complicates study design as much as it complicates anything else. When a response falls away under repeated exposure, a study measuring a single administration and a study measuring a longer schedule are not answering the same question, and a result from one does not carry over to the other. Which of the two a paper did is stated in its methods, and that is where to settle it.
| Length | 6 amino acids |
| Target | Ghrelin receptor |
| Known for | Strong GH response |
| Drawbacks | Cortisol and prolactin rise, desensitisation |
| Superseded by | Ipamorelin |
| Stocked here | No, reference page |
| Closest product | Ipamorelin peptide pen |
| Category | Research use only |
The measurable properties of the compound, and nothing past them.
We do not supply hexarelin
The compound it was superseded by is in the catalogue and does the same job with a cleaner profile. Stocking both would mean selling the older one to people who had not been told why it was replaced.
If a secretagogue is what you are looking for, the ipamorelin page and the combination pen page cover the current approach.
Traffic for what is hexarelin tends to arrive from lists of growth hormone peptides rather than from the literature, which is part of why this page reads the way it does. If the surrounding field is the real interest, the muscle and performance research area sets out how the releasing-hormone route and the ghrelin-receptor route differ from each other.
Why the secretagogue family is a doping question
Any compound that raises growth hormone output is an anti-doping matter before it is anything else. The secretagogues sit inside the peptide hormone and growth factor category described on our page on the prohibited list, and that category is written by mechanism, so a molecule does not need to be named individually to be caught by it.
The list is revised each January and published in full by the agency that maintains it. Anyone competing under those rules should read the current WADA Prohibited List directly rather than any supplier page, ours very much included.
For the research itself the picture is different without being simpler. The work indexed on PubMed is largely older physiology, much of it predating the selective compounds, which is worth knowing before treating any of it as current. Where a protected releasing-hormone analogue is the comparison you want, the tesamorelin page covers one with a finished programme behind it.
Hexarelin in the catalogue
HPLC analysis on every batch, with a 99% release threshold.
Where Hexarelin fits in
Where this article sits in the wider knowledge base.
About Hexarelin
The things people check first.