Hexarelin
| Category | Growth Hormone Secretagogues |
| Goals | Muscle & Performance |
| Evidence level | Preclinical (early human GH/cardiac studies; no approved use) |
| Legal status | Research-only — not approved for human use |
| FDA status | Not approved; never marketed |
| Half-life | ~55 minutes (human, IV) |
| Routes | Subcutaneous · Intravenous (in studies) |
| CAS / MW / Sequence | 140703-51-1 · ~887 g/mol · 6-aa His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH2 |
| Last reviewed | 2026-06-05 |
In one line
A potent synthetic hexapeptide GHRP (growth-hormone-releasing peptide) — one of the strongest GH-releasing peptides studied — notable for a distinctive direct cardiac action but also for tachyphylaxis (the GH response fades with repeated dosing).
Evidence at a glance
Hexarelin was studied in early human trials for GH release and cardiac effects, but development was discontinued and it is not approved anywhere. Much of what is cited for muscle/performance is preclinical or anecdotal. Its strong potency comes with a well-documented desensitization problem. See Evidence Grading Explained and the Disclaimer.
Key Takeaways
- A GHRP (ghrelin-receptor agonist), structurally a 2-methyl-Trp analog of GHRP-6 — among the most potent GH releasers of its class.
- Acts at the GHS-R1a (ghrelin) receptor on the pituitary; unlike GHRH analogs (Sermorelin, CJC-1295) it works through a different receptor and is often paired with one.
- Tachyphylaxis is the headline drawback: in repeated-dosing studies the GH response attenuates substantially over weeks (reversible after washout).
- Pharmacologically unusual for GH-independent cardiac effects via the CD36 scavenger receptor — a major reason it was studied for heart conditions.
- Less suited to long, continuous “anti-aging” use than gentler secretagogues like Ipamorelin or MK-677 because of desensitization and broader hormone effects.
What Is It
Hexarelin (also “Examorelin”) is a synthetic six-amino-acid peptide in the GHRP family. It is closely related to GHRP-6, differing by a 2-methyl substitution on the D-tryptophan residue, which increases potency and stability. It does not occur naturally; it was developed as a powerful, orally/parenterally active growth-hormone secretagogue and as a probe for the (then newly characterized) GH-secretagogue receptor.
In fitness circles it is sought for the large GH pulses it can produce. In research it became notable for a second, surprising property: direct protective effects on the heart that appear independent of growth hormone.
Mechanism of Action
- GHS-R1a (ghrelin receptor) agonism (established) — binds the ghrelin receptor on pituitary somatotrophs to trigger a strong GH pulse; synergizes with GHRH-receptor agonists.
- Multi-hormone release (clinical observation) — unlike the selective Ipamorelin, hexarelin can also raise ACTH, cortisol, and prolactin, a less clean profile.
- CD36-mediated cardiac action (preclinical) — binds the CD36 scavenger receptor on cardiomyocytes, producing cardioprotective/anti-fibrotic effects independent of GH in animal models.
- Tachyphylaxis (established) — sustained, non-pulsatile receptor activation downregulates the response; repeated dosing blunts GH output (reversible after a washout).
Limitations
Most muscle/performance claims are extrapolated from GH-release data and animal work, not from controlled human performance trials. The cardiac findings, while intriguing, are largely preclinical, and clinical development was halted.
Evidence by Outcome
| Outcome | Evidence | Notes |
|---|---|---|
| Acute GH release | Clinical | Potent GH-releasing effect shown in human dose-response studies |
| GH response over repeated dosing | Clinical | Documented attenuation (tachyphylaxis), reversible after washout |
| Cardioprotection (ischemia, fibrosis) | Preclinical | Animal/cell data via CD36; not confirmed in large human trials |
| Muscle growth / performance | Anecdotal / Preclinical | Extrapolated from GH pulses; no controlled human performance RCTs |
| ACTH/cortisol/prolactin elevation | Clinical | Documented off-target hormone release |
Reported Dosing
Not medical advice
Hexarelin is not approved; there is no established human therapeutic dose. Figures below are as reported in community/non-clinical sources and are documented for educational purposes only. See Reconstitution & Dosing Math and Injection Technique.
| Route | Dose (reported) | Frequency | Notes |
|---|---|---|---|
| Subcutaneous | ~100 µg | 1–3× daily | Short cycles to limit tachyphylaxis |
| Subcutaneous | ~1–2 µg/kg | Per dose | Body-weight-based figure from study literature |
Pharmacokinetics
Hexarelin has a half-life of roughly 55 minutes after IV dosing in humans (longer than native ghrelin and longer than Sermorelin). It is active subcutaneously and was even studied with intranasal/oral routes. Despite reasonable PK, its practical limitation is pharmacodynamic — the receptor response fades with repeated exposure regardless of plasma levels. See Half-Life & Pharmacokinetics.
Side Effects & Risks
- Tachyphylaxis — the GH-boosting effect diminishes over weeks of continuous use (reversible after a ~4-week washout in study data).
- Off-target hormone release — transient rises in cortisol, ACTH, and prolactin; less “clean” than Ipamorelin.
- GH-axis effects with overuse: water retention, joint aches, numbness/tingling, insulin-sensitivity changes, possible increased appetite (ghrelin-receptor activity).
- Human safety data is limited and dated; chronic-use safety is not established.
- Sourcing risk — sold as a research chemical with variable identity/purity. See Side Effects & Risk Management, Bloodwork & Monitoring, Red Flags & Scams.
Cycling
Because of tachyphylaxis, anecdotal protocols keep hexarelin to short, intermittent cycles (e.g. a few weeks on, with washout) rather than continuous use — the opposite of how gentler secretagogues are run. No evidence-based standard exists. See Cycling.
Stacks It Appears In
- Conceptually paired with a GHRH analog (Sermorelin or CJC-1295) so the two receptors act synergistically — the same dual-pathway logic as CJC-1295 + Ipamorelin.
- Compared against milder secretagogues Ipamorelin and MK-677 for routine use.
Comparisons
- vs Ipamorelin — both are GHRPs at the same receptor, but Ipamorelin is selective/clean (minimal cortisol/prolactin) and better suited to chronic use; hexarelin is more potent but prone to tachyphylaxis and off-target hormones.
- vs CJC-1295 / Sermorelin — those are GHRH-receptor agonists; hexarelin is a ghrelin-receptor agonist, often combined with them.
- vs MK-677 — MK-677 is an oral, long-acting ghrelin-receptor agonist; hexarelin is injectable and shorter-acting with stronger tachyphylaxis.
Sourcing & Quality
Hexarelin is sold almost exclusively as a lyophilized research chemical, so identity and purity are not guaranteed. Verify before trusting a product: How to Read a CoA, Third-Party Testing, Red Flags & Scams. Reconstitution and storage: Reconstitution & Dosing Math, Storage & Handling. No vendors are endorsed here.
Legal & Regulatory Status
(As of 2026-06-05.) Hexarelin is not approved by the FDA or other major regulators and was never marketed; clinical development (for GH testing and cardiac indications) was discontinued. It is sold only as a research chemical, not for human use, and is prohibited in tested sport (WADA bans GH secretagogues). Legal status varies by country. See Regulatory & Legal Status.
FAQ
Is hexarelin approved for anything? No. It was studied but never approved or marketed; it remains research-only.
Why doesn’t it keep working? Continuous activation of the ghrelin receptor causes tachyphylaxis — the GH response fades. A washout restores it, which is why short cycles are described.
How is it different from Ipamorelin? Same receptor, but hexarelin is more potent and also raises cortisol/prolactin, while Ipamorelin is more selective and gentler — usually preferred for routine use.
What’s the deal with the heart effects? In animals, hexarelin binds the CD36 receptor on heart cells and shows protective effects independent of GH — promising but preclinical.
References
- Ghigo E. et al. (1994). “Growth hormone-releasing activity of hexarelin in humans. A dose-response study.” — human GH-release data.
- Imbimbo B.P. et al. (1994). “Growth hormone-releasing activity of hexarelin in humans… kinetics.” — human PK (~55 min half-life).
- Mao Y. et al. (2014). “The cardiovascular action of hexarelin.” Journal of Geriatric Cardiology (PMC4178518) — CD36/cardioprotection review.
- Hexarelin entries — Cayman Chemical (structure/CAS), ChemicalBook (CAS 140703-51-1).
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