Hexarelin
A synthetic hexapeptide GHS-R1a agonist carrying a 2-methyl-D-tryptophan substitution that gives it higher receptor affinity — and consequently larger peak GH release — than most other synthetic GH secretagogues in its class. Reportedly investigated for growth hormone stimulation, muscle recovery, and cardiac function; early-phase human pharmacodynamic and cardiac studies have been published. Human trials confirm potent GH secretion; no controlled trials have established therapeutic efficacy for the endpoints most frequently discussed in community contexts.
Side effects & risks
Hexarelin has been studied in human pharmacokinetic and pharmacodynamic trials, providing a better-characterised safety signal than many purely preclinical compounds. However, no large-scale, long-duration safety trial has been conducted, and the risk profile for sustained community-style use is not established.
In controlled human studies, the most consistently documented adverse effects at doses producing GH responses were transient elevation of cortisol and prolactin. Arvat et al. (1997, Peptides; PMID 9285939) characterised GH, prolactin, ACTH, and cortisol responses to hexarelin in human subjects, and noted these hormonal effects. The cortisol and prolactin responses to hexarelin are more pronounced than those observed with ipamorelin at comparable GH-stimulating doses, a distinction noted across multiple comparative pharmacodynamic studies.
Desensitisation — attenuation of the GH response with repeated administration — has been documented in human studies. Controlled human pharmacological studies found that repeated hexarelin administration over seven days produced a significant reduction in peak GH response compared with first-dose values. The clinical implications of rapid desensitisation for community-style extended protocols have not been characterised.
Cardiovascular effects require specific attention. Hexarelin's cardioprotective effects in animal models involve direct cardiac GHS-R1a activation; in humans, studies in patients with cardiac dysfunction (such as those with coronary artery disease) have been conducted. The cardiovascular profile of hexarelin in otherwise healthy individuals using it as a research chemical has not been specifically evaluated.
Appetite stimulation is reported with hexarelin but is generally characterised as less pronounced than with GHRP-6, based on comparative pharmacodynamic studies.
A theoretical concern shared with all growth hormone secretagogues is the potential for IGF-1-mediated effects over extended administration; the magnitude of any such risk from hexarelin is not established in peer-reviewed literature.
Hexarelin is not approved for human therapeutic use in any major regulatory jurisdiction. Individuals obtaining it as a research chemical assume an undetermined risk profile.
Evidence summary
Latest studies
Protective and restorative effects of hexarelin on MPTP-induced lung injury in mice.
In this mouse experiment, 50 animals received an intranasal dose of MPTP, a neurotoxin used to model Parkinson-like injury, which also damaged their lungs - thickened alveolar walls, edema, congestion, and inflammatory infiltration. Hexarelin, a growth hormone secretagogue, was given by injection either before or after the toxin exposure. Both timings reduced visible tissue damage and improved markers of oxidative stress, inflammation, and cell death, with lower Caspase-3 and IL-6 staining and higher superoxide dismutase. Giving hexarelin after the toxin worked better than giving it beforehand, which the authors attribute to cytoprotective pathways being actively engaged during ongoing injury.
Hexarelin promotes the survival of retinal ganglion cells after optic nerve transection.
This study tested whether the peptide hexarelin could help retinal nerve cells survive after damage to the optic nerve in hamsters. After the optic nerve was cut, animals received daily injections of hexarelin at different doses for five days, and surviving retinal ganglion cells were counted a week later. Higher single daily doses led to more surviving cells: survival rose from about 51% with salt water to 62%, 69% and 75% at increasing hexarelin doses. Giving hexarelin twice a day boosted survival further, with the highest dose showing the best result. The researchers concluded that hexarelin increased nerve-cell survival in a dose-dependent way, with twice-daily dosing at the higher amount being most protective. This is an early animal study measuring cell survival only, not actual vision, and it does not show what hexarelin does in people.
The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.
This review looks at peptides sold online as research compounds that aim to boost growth hormone and IGF-1, a growth-related hormone. It covers several of the peptides we track, including sermorelin, tesamorelin, CJC-1295, GHRP-6, hexarelin, and ipamorelin. The authors compare what published science actually shows against the dosing routines people use on their own, and they sort the compounds by how much human evidence exists, from well-studied to none at all. Their key point is that claimed benefits for performance or body composition are not established, and that reported side effects include raised prolactin and cortisol, fluid retention, joint and muscle aches, appetite and blood-sugar changes, and injection-site reactions. Because these products are unregulated, their actual contents and doses are often uncertain. This is a summary of existing knowledge offered to help readers understand the risks.
Community discussion
Community-reported · not verified
These are synthesised observations from public forum discussions. They are community-reported, not clinically verified, and should not inform any health decision. The peptide does not cure, treat, or prevent any condition based on these reports.
“GHRP-2, GHRP-6, hexarelin, ipamorelin: what 'growth hormone secretagogue' actually covers”
An educational thread clarifying what the term growth hormone secretagogue covers, comparing GHRP-2, GHRP-6, hexarelin, and ipamorelin and how they differ within that class.
Reported protocols (with caveats)
| USE | ROUTE | COMMON DOSE | FREQUENCY | TYPICAL CYCLE |
|---|---|---|---|---|
| GH stimulation (community-reported) | SC injection | 100–200 mcg | 1–2× daily | 3–4 weeks (then break to limit desensitisation) |
| Combination with GHRH analogue (community-reported) | SC injection | 100 mcg hexarelin | 1–2× daily with CJC-1295 or sermorelin | 3–4 weeks |
Frequently asked questions
- How does hexarelin differ from GHRP-6?
- Both hexarelin and GHRP-6 are GHS-R1a (ghrelin receptor) agonists. Hexarelin is generally more potent on a per-microgram basis due to a structural modification (2-methyl-D-tryptophan substitution) that increases receptor affinity. Hexarelin also produces more pronounced cortisol and prolactin elevation than GHRP-6 in comparative pharmacodynamic studies, and undergoes more rapid desensitisation with repeated dosing. Its appetite-stimulating effect is generally considered less marked than GHRP-6's.
- Is there evidence for hexarelin's cardiac effects in humans?
- Yes, to a limited degree. A study in patients with severe left ventricular dysfunction found GH-independent cardiotropic activity following hexarelin administration (Imazio et al., 2002, Eur J Heart Fail; PMID 11959048). These findings suggest a GH-independent cardiac mechanism — consistent with preclinical data — but the study is too small and short-term to constitute evidence of sustained clinical benefit. No adequately powered trial in cardiac patients has been completed.
- What is desensitisation and does it affect hexarelin?
- Desensitisation (tachyphylaxis) refers to the attenuation of a pharmacological response with repeated administration. With hexarelin, published human pharmacological studies demonstrate that peak GH response declines significantly over seven days of repeated administration. This is a documented pharmacological limitation of hexarelin compared with some other GHS peptides. Community discussions frequently acknowledge this phenomenon and adapt protocols accordingly.
- Is hexarelin legal to buy or use?
- Hexarelin is not approved for human therapeutic use in the United States, Australia, Canada, the UK, or the EU. In most jurisdictions it is sold as a research chemical. Regulatory status varies by country and is subject to change; verify current status with a qualified legal or clinical professional.
- What are the known side effects of hexarelin?
- Controlled human studies document transient cortisol and prolactin elevation at GH-stimulating doses. These hormonal effects are more pronounced with hexarelin than with ipamorelin. Desensitisation of the GH response with repeated use has been documented in humans. Mild appetite stimulation and injection-site reactions are reported in community accounts. The full risk profile of sustained community-protocol use has not been evaluated in controlled trials.