I’ve run a lot of growth hormone secretagogues over the years. Hexarelin is the one people ask about the most and understand the least. It is also the one I get most cautious about, because it is the strongest GH pulse you can get from an injectable hexapeptide, and strongest is not the same as best for you.
TL;DR
- Hexarelin is a synthetic 6-amino-acid peptide, built off the older GHRP-6 backbone, that activates the GHS-R1a ghrelin receptor and triggers a growth hormone pulse from the pituitary.
- It also activates a second, separate receptor, CD36, on heart tissue, which is where its cardiac research comes from and where a real evidence gap starts.
- It is not FDA approved for any use, it is sold only as a research chemical, and it is on the WADA banned list under S2 as examorelin.
- It produces the largest acute GH release of any studied GHRP, but also the largest cortisol, ACTH, and prolactin rise, and the GH response fades by roughly half after 16 weeks of daily dosing.
- My Natural Plus take: pulse it in short blocks, never run it daily for months, and use bloodwork to decide when to stop.
What Hexarelin Is, and Why It Is Not a Supplement
Hexarelin (also sold under the research name examorelin) is a synthetic hexapeptide, meaning 6 linked amino acids, developed in the early 1990s as a more potent successor to GHRP-6. It is not sold as a dietary supplement anywhere legitimate. It ships as a research chemical only, with no FDA approval for human injection, no manufacturing oversight comparable to a prescription drug, and no guarantee that what is in the vial matches the label. That is the honest starting point, stated first, before any benefit gets discussed.
It is also a banned substance. The World Anti-Doping Agency (WADA) lists examorelin by name under section S2, alongside GHRP-1 through GHRP-6, ipamorelin, and MK-677. Compete in any tested sport and it disqualifies you the same as anabolic steroids do.
The hormonal cost belongs up front too, not buried under the benefits. Every human dosing trial measured a real rise in cortisol, ACTH, and prolactin alongside the GH pulse. In one dose-response study, the ACTH rise ran about 7 times higher than the body’s own corticotropin-releasing hormone produces alone, with cortisol running about 4 times higher. That happens with essentially every dose, which is why hexarelin is not the peptide I hand to someone who has never run a GH secretagogue before.
The Mechanism: One Receptor for Growth Hormone, a Second One for the Heart
Hexarelin works through the GHS-R1a receptor, the same one ghrelin, your body’s own hunger hormone, activates. Sitting on the pituitary’s somatotroph cells and on neurons in the hypothalamus, GHS-R1a triggers a calcium-driven release of stored growth hormone the moment hexarelin binds it. A 1994 trial testing intravenous, subcutaneous, intranasal, and oral hexarelin in 12 healthy men found a strong, reproducible GH pulse through every route, including oral, which most peptides in this class cannot manage at all. That oral activity is why hexarelin got taken seriously as a drug candidate rather than dismissed as another injectable curiosity.
What makes hexarelin different from the rest of the GHRP family is a second receptor entirely. In 2002, researchers labeled rat cardiac membranes with a radioactive hexarelin derivative and traced the binding protein to CD36, a glycoprotein on heart muscle cells and the endothelium lining small coronary vessels. That receptor has nothing to do with growth hormone. Activating CD36 in an isolated, perfused heart changed coronary perfusion pressure directly, and the effect disappeared entirely in mice bred without the CD36 gene. Hexarelin is running 2 separate biological programs from one molecule: a GH pulse through GHS-R1a, and a direct cardiac action through CD36.
Law 4, Self-Regulating Systems: Why the Cortisol Bump Is the Tell
Every biological system fights to hold its baseline. Push a lever hard enough and the body pushes back, and hexarelin is one of the cleanest examples of that law I have found in any compound I have run.
Here is the data that proves it. A 16-week trial dosed subjects with hexarelin twice daily and tracked the GH response to a fresh injection at weeks 0, 1, 4, and 16. The area under the GH curve dropped from about 19.1 down to 10.5 micrograms per liter per hour (p = 0.0003), a decline that partially recovered after the injections stopped. That is receptor desensitization in real time: the same dose producing roughly half the GH pulse by week 16 that it produced on day one.
Now look at the other side of the ledger. A companion trial on the same chronic schedule found the pituitary-adrenal axis and prolactin secretion did not build the same tolerance. The cortisol and prolactin cost of each dose stayed roughly where it started, even as the GH payoff kept shrinking. That asymmetry is the whole argument for pulsing over daily use: the same hormonal tax for a shrinking GH return. Cycling in short blocks, with real breaks between them, keeps the receptor answering instead of just running the bill up.
Hexarelin Dosage: What the Trials Used
This is not a prescribing chart for a research chemical. It is what the clinical literature ran, and what nearly 3 decades of underground use has settled on, because those 2 numbers line up closely enough to be worth knowing.
The acute human dose-response studies bracketed the effective range between 0.5 and 2 micrograms per kilogram of body weight, delivered intravenously or subcutaneously. For a 70 kg (154 lb) man, that works out to roughly 35 to 140 micrograms per dose. The 16-week desensitization trial ran 1.5 micrograms per kilogram, twice daily, around 105 micrograms per injection for that same 70 kg man. The community that has run hexarelin since the mid-1990s settled in almost exactly that window, dosing in the 100 to 200 microgram range per pulse, timed at night or pre-training, and cycling in blocks of roughly 4 to 8 weeks followed by a break at least that long. That last part is the desensitization curve translated into a schedule.
My own experience matches what the receptor biology predicts. The first thing I noticed running hexarelin was hunger and water retention inside the first week, the prolactin and cortisol data talking. I have pulled bloodwork before and after multiple blocks over the years and watched IGF-1 climb every time I started a fresh cycle, then flatten out if I pushed past 2 months straight. When it flattens, I stop.
Hexarelin vs Ipamorelin: Which One Fits Your Goal
This is the comparison people ask me about constantly, and the honest answer is they are not competing for the same job. Hexarelin is the strongest acute GH pulse in this drug class, and it carries the largest cortisol, ACTH, and prolactin load to get there. Ipamorelin was engineered specifically to avoid that cross-reactivity: it activates the same GHS-R1a receptor for GH release without meaningfully moving cortisol, ACTH, or prolactin at studied doses. Want the biggest single GH spike and you already track labs closely, hexarelin wins that contest. Want a clean, repeatable daily GH nudge without the hormonal noise, ipamorelin is the better tool, and it does not desensitize nearly as fast because you are not leaning on the receptor nearly as hard.
Stacking hexarelin with a GHRH analog like CJC-1295 is a different move, because CJC-1295 works through the GHRH receptor, not GHS-R1a. 2 independent receptors converging on the same somatotroph cell make the combined GH pulse genuinely additive rather than competing for the same binding site, which is why that pairing shows up so often in protocols built around this drug class. I don’t have a dedicated CJC-1295 or ipamorelin write-up live on this site yet. When I do, I will link them here.
The tissue-repair side of my protocol stack lives in my BPC-157 and TB-500 protocol, and if you want the oral alternative that skips injections entirely, I broke down 12 weeks of that experiment with full bloodwork in my MK-677 review. Both hit completely different receptors than hexarelin does, which is exactly why they stack instead of compete.
Who This Is For
This fits people who have already run a milder GH secretagogue like MK-677 or ipamorelin, already read their own bloodwork, and want the strongest acute pulse available for a defined block of time rather than a daily maintenance compound. It fits athletes over 35 chasing recovery speed who monitor fasting glucose and IGF-1 along the way. It disqualifies anyone in a tested sport outright, and it belongs nowhere near an undiagnosed heart condition or someone unwilling to cycle off.
| Timeframe | What to expect |
|---|---|
| Week 1 | The first GH pulse hits within an hour of dosing. Hunger, water retention, and vivid dreams are the most commonly reported early markers, tied to the prolactin and cortisol rise. |
| Week 2 to 4 | Recovery speed and sleep depth are where most users first notice a real shift. IGF-1 on a follow-up panel is usually climbing by this point. |
| Week 8 | Trial data shows the GH response starting to fade against the same dose. This is the point to plan your break, not push through it. |
| Week 16 | In the desensitization trial, the GH area-under-curve had dropped roughly in half from baseline. Daily use past this point is buying diminishing returns for the same hormonal cost. |
Hexarelin Cardiac Research: What the Trials Found
Most peptide guides mention hexarelin’s cardiac research in one line. It is the most interesting and least understood part of this molecule.
In 2002, a trial gave hexarelin to patients with severe left ventricular dysfunction from 2 different causes: ischemic cardiomyopathy and dilated cardiomyopathy. In the ischemic group, hexarelin raised ejection fraction acutely, the same way it does in healthy subjects and in patients with growth hormone deficiency. In the dilated cardiomyopathy group, ejection fraction stayed flat despite an equivalent GH pulse. Same drug, same GH response, 2 different heart conditions, 2 different outcomes, exactly what you would predict once you know CD36 runs independently of the GH pathway. Whatever drove the cardiac effect in the ischemic group was not the growth hormone.
Here is the evidence gap I will not paper over: every human cardiac study on hexarelin is an acute, short-course infusion under medical supervision, measuring ejection fraction in the moment. There is no long-term outcome trial in humans, no mortality data, no study on chronic, unsupervised, underground dosing. Animal models have shown hexarelin reducing cardiac fibrosis after induced heart attacks in mice, a genuinely exciting signal for a receptor pathway nobody else in this compound class has. But strong in the model is not proven in people, and nobody has run that trial. If you have an underlying heart condition, this is not a peptide to self-experiment with outside a doctor’s supervision.
References
- Ghigo E, Arvat E, Gianotti L, et al. “Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man.” J Clin Endocrinol Metab. 1994;78(3):693-698. DOI: 10.1210/jcem.78.3.8126144 (PMID: 8126144)
- Rahim A, Toogood AA, Shalet SM. “Growth hormone status during long-term hexarelin therapy.” J Clin Endocrinol Metab. 1998;83(5):1644-1649. PMID: 9589671
- Rahim A, Ross RJ, et al. “The effect of chronic hexarelin administration on the pituitary-adrenal axis and prolactin.” Clin Endocrinol (Oxf). 1999;50(5):563-571. PMID: 10341859
- Ghigo E, Arvat E, Ramunni J, et al. “Adrenocorticotropin- and cortisol-releasing effect of hexarelin, a synthetic growth hormone-releasing peptide, in normal subjects and patients with Cushing’s syndrome.” J Clin Endocrinol Metab. 1997;82(8):2439-2444. PMID: 9253314
- Bodart V, Febbraio M, Demers A, et al. “CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart.” Circ Res. 2002;90(8):844-849. PMID: 11988484
- Imazio M, Bobbio M, Broglio F, et al. “GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to dilated and ischemic cardiomyopathy.” Eur J Heart Fail. 2002;4(2):185-191. PMID: 11959048
- Ishida J, Saitoh M, Ebner N, Springer J, Anker SD, von Haehling S. “Growth hormone secretagogues: history, mechanism of action, and clinical development.” JCSM Rapid Communications. 2020;3:25-37. DOI: 10.1002/rco2.9
- World Anti-Doping Agency. “2026 Prohibited List, S2: Peptide Hormones, Growth Factors, Related Substances and Mimetics” (lists examorelin/hexarelin). wada-ama.org/en/prohibited-list
Frequently Asked Questions
What is hexarelin?
Hexarelin is a synthetic 6-amino-acid growth hormone secretagogue that activates the GHS-R1a ghrelin receptor, triggering a GH pulse from the pituitary. It also activates CD36, a separate receptor on heart tissue. It is sold only as a research chemical, unapproved for human use.
What dose of hexarelin did the trials use?
Acute dose-response trials ran 0.5 to 2 micrograms per kilogram of body weight. The chronic 16-week trial used 1.5 micrograms per kilogram twice daily, which works out to roughly 100 micrograms per injection for a 70 kg man. The GH response to that dose had dropped by roughly half by week 16.
Is hexarelin safe, and what is the hexarelin cardiac risk?
It is not FDA approved and carries documented risks: a large acute rise in cortisol, ACTH, and prolactin with every dose, plus receptor desensitization with daily use. Its cardiac data comes from acute, supervised infusion studies in sick patients, not chronic outcome trials in healthy people, so long-term cardiac safety under unsupervised use is an open question.
Should I stack hexarelin with CJC-1295 or ipamorelin?
CJC-1295 works through a different receptor (GHRH, not GHS-R1a), so pairing it with hexarelin is genuinely additive rather than competing for the same binding site. Ipamorelin hits the same GHS-R1a receptor without the cortisol and prolactin load, making it the better daily-use alternative if hexarelin’s hormonal cost is the sticking point.
Who should consider hexarelin?
People who have already run a milder GH secretagogue, track their own bloodwork, and want the strongest available acute GH pulse for a defined cycle length rather than daily maintenance. Skip it if you are new to GH secretagogues, carry an undiagnosed heart condition, or compete in a tested sport.
This article covers the published research and my own experience running hexarelin. It is not medical advice or an instruction to buy or use an unapproved research chemical. Hexarelin is not sold through Enhanced Labs or any of my other stores; nothing here is an affiliate link.
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