Hexarelin
A potent growth hormone secretagogue peptide that also has cardioprotective properties independent of GH release.
What is Hexarelin?
Hexarelin is a synthetic hexapeptide growth hormone secretagogue that stimulates GH release through the ghrelin receptor (GHS-R1a). It is one of the most potent GHRP peptides and uniquely possesses cardioprotective properties independent of GH release, acting directly on cardiac tissue.
What Hexarelin Is Investigated For
Hexarelin is investigated for two largely independent effects: growth hormone release through the ghrelin/GHS-R1a receptor, and a cardioprotective/anti-atherosclerotic profile mediated through the CD36 scavenger receptor that other GHRPs do not engage. The strongest direct human evidence is for its acute GH- and cortisol-releasing potency — multiple clinical trials from the 1990s characterized both the dose response and the rapid desensitization that follows repeated dosing. The cardiac, anti-fibrotic, and neuroprotective claims rest almost entirely on preclinical rodent models (post-MI, ischemia-reperfusion, spontaneously hypertensive rats, ApoE-knockout atherosclerosis) and have never been tested in a human cardiovascular endpoint trial. Hexarelin produces a larger GH pulse than ipamorelin or GHRP-2, but at the cost of greater cortisol and prolactin elevation and faster tachyphylaxis — 'most potent' is not the same as 'most useful' for chronic protocols.
History & Discovery
Hexarelin was developed in the early 1990s in Italy by Romano Deghenghi and colleagues at Europeptides (later associated with Mediolanum Farmaceutici), part of the second-generation wave of synthetic GHRPs that followed Cyril Bowers' pioneering work at Tulane in the 1980s. The medicinal-chemistry goal was to improve on GHRP-6 by increasing potency and metabolic stability while retaining the ghrelin-receptor agonism responsible for GH release. Deghenghi's group arrived at the hexapeptide His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH2, which showed markedly higher GH-releasing potency than GHRP-6 in both animal and early human studies and a longer duration of action. Hexarelin attracted considerable academic interest through the 1990s, and the compound was explored in clinical trials for GH-deficient children, cardiac protection, and as a diagnostic tool. None of these programs led to regulatory approval. A distinctive chapter in its history came with the discovery in the late 1990s and early 2000s that hexarelin binds the CD36 scavenger receptor on cardiac tissue and macrophages, producing cardioprotective, anti-fibrotic, and anti-atherosclerotic effects that operate independently of GH release — a receptor that neither endogenous ghrelin nor the other major GHRPs engage with the same affinity. This dual-receptor profile made hexarelin an unusual research tool even as its therapeutic development stalled. It migrated into the research-chemical and compounding-pharmacy market during the 2010s.
How It Works
Hexarelin triggers a strong burst of growth hormone from the pituitary gland. Unlike other similar peptides, it also directly protects heart cells from damage, making it unique among growth hormone-releasing peptides.
Hexarelin binds GHS-R1a on pituitary somatotrophs, activating PLC/IP3/DAG signaling and calcium influx to trigger GH vesicle exocytosis. It also stimulates the HPA axis via arginine vasopressin (AVP), elevating ACTH and cortisol. Independently of GH release, hexarelin binds CD36 scavenger receptors on cardiac tissue, macrophages, and adipocytes. In the heart, CD36 activation triggers PPARgamma/PGC-1alpha signaling, reducing fibrosis and protecting cardiomyocytes from apoptosis (angiotensin II, doxorubicin). In macrophages, it upregulates sterol transporters (ABCA1, ABCG1) and promotes cholesterol efflux, countering atherosclerosis. In adipocytes, CD36 binding promotes mitochondrial biogenesis and a fat-burning phenotype. The hexapeptide structure (His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH2) provides high receptor affinity but also significant cross-reactivity with cortisol and prolactin pathways. Hexarelin also modulates MAPK and PI3K/Akt survival pathways, contributing to neuroprotective effects against oxidative stress.
Evidence Snapshot
Human Clinical Evidence
Moderate. Multiple clinical trials demonstrate potent GH release, HPA axis stimulation, and desensitization kinetics. Cardiac and metabolic benefits primarily from preclinical models. Not FDA-approved.
Animal / Preclinical
Strong. Cardioprotective effects (anti-fibrotic, anti-apoptotic, anti-atherosclerotic) well-demonstrated in rodent models including post-MI, ischemia-reperfusion, angiotensin II-induced hypertrophy, spontaneous hypertension, diabetic cardiomyopathy, and ApoE knockout atherosclerosis models. Neuroprotective effects shown in neonatal brain injury, hippocampal progenitor cells, and SOD1-mutant neuroblastoma models. Anti-inflammatory activity demonstrated in acute lung injury. Metabolic benefits (reduced fat accumulation, improved insulin sensitivity) shown in obese mice via GHS-R activation.
Mechanistic Rationale
Strong. Dual receptor mechanism (GHS-R1a for GH release, CD36 for cardioprotection) is well-characterized. PPARgamma/PGC-1alpha downstream signaling, cholesterol efflux pathways, and MAPK/PI3K-Akt survival pathways are established.
Research Gaps & Open Questions
What the current literature has not yet settled about Hexarelin:
- 01Long-term (>6 month) human safety data at chronic wellness-range doses is essentially absent; the published clinical literature is dominated by short-duration studies and single-dose pharmacology.
- 02The clinical significance of hexarelin's cardioprotective CD36-mediated effects — convincingly demonstrated in rodent models of MI, ischemia-reperfusion, and atherosclerosis — has never been tested in a human cardiovascular endpoint trial.
- 03Quantitative characterization of desensitization kinetics across different dosing cadences (once vs. twice vs. three times daily; continuous vs. cycled) is thin; most of what is said about hexarelin's faster tachyphylaxis rests on a small number of studies.
- 04The chronic consequences of hexarelin's cortisol and prolactin elevation at wellness doses — whether they cumulate into clinically meaningful HPA-axis or reproductive-endocrine effects over months — has not been characterized.
- 05Head-to-head comparisons with GHRP-2 and ipamorelin on long-duration body-composition and functional endpoints in non-deficient adults are absent.
- 06Pharmacokinetic-pharmacodynamic modeling of hexarelin in older adults, the demographic most commonly using it in wellness settings, lags behind the younger-adult data.
Forms & Administration
SC or IV injection. Typical dose: 1-2mcg/kg, 2-3 times daily. Often cycled (4-8 weeks on, 4 weeks off) to prevent desensitization. All injectable peptides should only be administered under the guidance of a qualified healthcare provider. Never self-administer without clinician oversight.
Dosing & Protocols
The ranges below reflect protocols commonly discussed in the literature and by clinicians — not a prescription. Actual dosing for any individual should be determined by a qualified healthcare provider who knows the patient.
Typical Range
Published hexarelin clinical work has used a wide dose range; the most commonly cited effective range for GH release in adults is 1.5–2 mcg/kg per dose (roughly 100–200 mcg for a 70-kg adult), administered subcutaneously two to three times daily in chronic protocols. The original clinical dose-response studies (Imbimbo, Ghigo, and colleagues) used single intravenous doses as high as 2 mcg/kg to characterize the pituitary response. Higher doses (approaching 600 mcg) have been explored but produce disproportionately larger cortisol and prolactin elevations without proportionally greater GH release, so most chronic protocols stay at the lower end.
Frequency
Hexarelin has a plasma half-life of roughly 60–90 minutes — longer than GHRP-2 or GHRP-6 — but the more important pharmacodynamic constraint is desensitization. Human studies show GH responsiveness declines with repeated dosing more quickly than for other GHRPs, especially at higher doses and with continuous use. Most protocols therefore use one to two injections per day rather than the three-times-daily cadence typical of GHRP-2 or ipamorelin. When stacked with a GHRH analog (CJC-1295, sermorelin), the dual-pathway synergy rationale applies, but hexarelin is less commonly chosen for daily stacks precisely because of its desensitization profile; it is more often used in shorter bursts.
Timing Considerations
Time of day
Morning fasted and bedtime are the two most common windows. Because hexarelin desensitizes faster than other GHRPs, most protocols use one to two doses per day rather than three.
Relative to meals
Fasted — at least 30 minutes before food and 2+ hours after a meal. Elevated insulin and amino acids substantially blunt GH release.
Relative to exercise
Independent of training in most protocols; a pre-workout dose is occasionally used in two-dose-per-day regimens.
Cycle Length
Cycling is a more critical consideration for hexarelin than for the other GHRPs because of faster desensitization. Commonly discussed protocols run 4–8 weeks on followed by at least 4 weeks off, with some clinicians shortening the on-phase to 3–4 weeks to better preserve GH responsiveness. Continuous use is not generally advocated for hexarelin even by aggressive wellness protocols. No long-duration human trial has validated any specific cycling pattern with body-composition or functional endpoints.
Protocol Notes
Hexarelin is supplied as a lyophilized powder, typically 2 mg or 5 mg per vial, reconstituted in bacteriostatic water. A 2 mg vial in 1 mL of BAC water yields 2,000 mcg/mL, making 100 mcg roughly 0.05 mL or 5 units on an insulin syringe. Subcutaneous injection into the abdominal fat pad is the standard route. Like other GHRPs, hexarelin acts through the ghrelin/GHS-R1a receptor, so timing on a relatively empty stomach matters — circulating amino acids and elevated insulin blunt GH release. Most protocols call for injection at least 30 minutes before eating or 2+ hours after a meal. Morning fasted and bedtime dosing are the two most common windows. Users who pursue hexarelin primarily for its cardioprotective CD36-mediated effects (rather than for GH release) sometimes use very low doses on a different cadence; this use case is entirely extrapolated from preclinical work and has no human trial validation.
Hexarelin is not FDA-approved for any indication. The numbers above describe commonly-referenced protocols drawn from a mix of published clinical work and wellness practice, not a prescription. Use should be supervised by a qualified clinician with appropriate IGF-1, cortisol, prolactin, and glucose monitoring given hexarelin's off-target hormonal effects.
Timeline of Effects
Onset
The acute GH pulse is immediate — peak plasma GH typically occurs within 15–30 minutes of subcutaneous injection, and the peak amplitude with hexarelin is among the largest produced by any GHRP at comparable dose. Subjective signals most commonly reported in the first 1–2 weeks include deeper sleep and reduced post-exercise soreness. Cortisol and prolactin elevations are also acute and measurable shortly after dosing.
Peak Effect
Serum IGF-1 typically rises over the first 2–4 weeks of consistent dosing; this window is often shorter than for ipamorelin or GHRP-2 because hexarelin's per-dose GH amplitude is larger. However, GH responsiveness tends to begin declining over the same window as somatotrophs desensitize. Subjective body-composition and recovery benefits most commonly plateau within 4–6 weeks, which is also the point at which many clinicians recommend cycling off. The IGF-1 peak achievable with hexarelin at typical wellness doses is comparable to or modestly higher than GHRP-2.
After Discontinuation
Endogenous pulsatile GH secretion returns to baseline within days to 1–2 weeks of stopping dosing, as the ghrelin-receptor occupancy clears and any desensitization reverses. IGF-1 drifts back to pre-treatment levels over 2–4 weeks. Cortisol and prolactin elevations normalize quickly. No post-cycle therapy is required — hexarelin does not suppress the HPG axis. The cardioprotective CD36-mediated effects observed in preclinical models (reduced fibrosis, improved post-infarct cardiac function) appear to persist longer than the acute GH-release effects in animal work, but this persistence has not been characterized in humans.
Common Questions
Who Hexarelin Is NOT For
- •Active or recent-history cancer — GH and IGF-1 elevation may accelerate proliferation of existing malignancies; clinicians universally exclude active cancer from GH-secretagogue protocols. Hexarelin's CD36 agonism may additionally interact with tumor biology in ways that have not been characterized in human oncology settings.
- •Pregnancy — no human pregnancy safety data; reproductive-toxicology characterization is absent, and hexarelin's pronounced HPA-axis activation raises additional theoretical concerns about fetal glucocorticoid exposure.
- •Breastfeeding — no data on transfer into breast milk or effects on nursing infants.
- •Diabetes or uncontrolled insulin resistance — GH opposes insulin action; hexarelin's stronger cortisol elevation relative to ipamorelin or GHRP-2 further antagonizes glycemic control and makes this contraindication more pointed than for other GHRPs.
- •Active hypercortisolism, Cushing's disease, or poorly controlled HPA-axis disorders — hexarelin meaningfully stimulates ACTH and cortisol via AVP-related pathways, and unmasking or worsening HPA-axis pathology is a defined risk.
- •Active acromegaly or pituitary adenoma — further stimulation of GH-producing cells is contraindicated.
- •Pediatric use outside a diagnosed GH deficiency under specialist supervision — hexarelin has been studied in pediatric GH-deficient populations in limited academic settings, but unmonitored use in children is not appropriate.
Drug & Supplement Interactions
Documented clinical drug interactions for hexarelin are sparse because no large post-marketing dataset exists; the relevant concerns are extrapolated from its pharmacology. Glucose-regulating medications — insulin, sulfonylureas, GLP-1 receptor agonists — interact with the combined counter-regulatory effects of elevated GH and elevated cortisol, and dose adjustment may be required over weeks of use. Because hexarelin elevates cortisol more than the other GHRPs, this interaction is clinically more relevant than for ipamorelin. Corticosteroids (prednisone, dexamethasone) interact with hexarelin in a dual way: acute glucocorticoid administration can actually enhance hexarelin's GH-releasing effect in the short term, while chronic glucocorticoid use suppresses spontaneous GH and blunts cumulative IGF-1 gains. Somatostatin analogs (octreotide, lanreotide) directly oppose GH release and will pharmacologically antagonize hexarelin. Dopamine agonists used for hyperprolactinemia may be indicated if hexarelin's prolactin elevation becomes clinically meaningful, though this is usually addressed by reducing dose or cycling rather than co-medication. Thyroid hormone status matters — uncorrected hypothyroidism blunts the GH response. Because hexarelin's CD36 agonism affects lipid handling and macrophage cholesterol efflux in preclinical models, theoretical interactions with statins and other lipid-modifying drugs exist but have not been characterized in humans. As with any peptide therapy, patients on any regular medication should disclose hexarelin use to their prescribing clinician.
Safety Profile
Common Side Effects
Cautions
- • Rapid desensitization with continuous use — cycling recommended
- • Greater cortisol/prolactin elevation than other GHRPs
- • Stimulates HPA axis via arginine vasopressin
- • Not FDA-approved for any indication
What We Don't Know
Long-term safety of chronic GHS-R1a and CD36 activation is not fully characterized. Impact of sustained PPARgamma activation in non-cardiac tissues needs further study.
Legal Status
United States
Hexarelin is not FDA-approved for any medical indication. It has historically been available through state-licensed compounding pharmacies under individualized prescription, though the FDA's ongoing 503A bulk-list review has challenged the compounding status of GH secretagogues generally, including hexarelin. It is widely sold in the research-chemical market labeled 'not for human consumption,' which is not an authorized channel for human use. Regulatory posture is actively evolving.
International
The European Medicines Agency and UK MHRA have not authorized hexarelin as a medicine despite its European origins. Australia's TGA classifies GH secretagogues as Schedule 4 prescription-only substances. Canada treats it as an unapproved investigational agent. No major regulator has approved hexarelin for chronic therapeutic use in any indication.
Sports & Competition
Hexarelin is explicitly prohibited under WADA's S2 category (Peptide Hormones, Growth Factors, Related Substances and Mimetics), which covers GH secretagogues and ghrelin-receptor agonists — prohibited at all times, both in and out of competition. LC-MS/MS urinary detection methods for hexarelin and its metabolites are well-established. Athletes subject to WADA, USADA, UKAD, or equivalent bodies must avoid it.
Regulatory status changes over time. Verify current local rules with a qualified professional.
Myths & Misconceptions
Myth
Hexarelin is the strongest GHRP and therefore the best choice for GH optimization.
Reality
Hexarelin does produce the largest acute GH pulse among the GHRPs at comparable doses, but 'strongest' is not a synonym for 'best.' Its higher cortisol and prolactin elevation, faster desensitization, and the resulting need for shorter cycles mean it is often a worse tool than ipamorelin or GHRP-2 for sustained IGF-1 elevation. The 'potency' framing conflates acute pulse amplitude with chronic clinical benefit.
Myth
Hexarelin's cardioprotective effects are established enough to recommend it for heart health.
Reality
The cardioprotective evidence is mechanistically compelling and preclinically extensive — CD36-mediated, PPARgamma-linked, demonstrated in multiple rodent models. But it has never been tested in a human cardiovascular endpoint trial. Translating 'cardioprotective in rats' to 'take this for your heart' is the exact kind of unwarranted leap the peptide space makes too often. The pharmacology is interesting; the clinical evidence does not yet support the recommendation.
Myth
Hexarelin works just like the other GHRPs, only stronger.
Reality
Hexarelin is the only major GHRP with meaningful CD36 scavenger-receptor affinity — a distinct binding target from GHS-R1a that drives its cardioprotective and anti-atherosclerotic effects in preclinical work. This dual-receptor profile makes it mechanistically different from GHRP-2, GHRP-6, and ipamorelin, not just a more-potent version of them.
Myth
Hexarelin desensitization is overstated — you can dose it continuously like the other GHRPs.
Reality
Human clinical studies have directly demonstrated declining GH responsiveness with repeated hexarelin dosing, and this effect is more pronounced than with GHRP-2. Cycling is not a 'just in case' precaution for hexarelin — it is a pharmacologically grounded practice based on documented tachyphylaxis.
Myth
Hexarelin is undetectable in drug testing because it is peptide-based.
Reality
WADA-accredited laboratories have validated LC-MS/MS urinary detection methods for hexarelin and its metabolites. Short plasma half-life does not equal undetectability — metabolites remain measurable for a window after dosing, and athletes have tested positive for hexarelin under WADA code.
Published Research
27 studiesProtective effects of hexarelin and JMV2894 in a human neuroblastoma cell line expressing the SOD1-G93A mutated protein
Using synchrotron radiation imaging techniques to elucidate the actions of hexarelin in the heart of small animal models
Hexarelin modulates lung mechanics, inflammation, and fibrosis in acute lung injury
Hexarelin modulation of MAPK and PI3K/Akt pathways in Neuro-2A cells inhibits hydrogen peroxide-induced apoptotic toxicity
Stimulation of endogenous pulsatile growth hormone secretion by activation of growth hormone secretagogue receptor reduces fat accumulation and improves insulin sensitivity in obese mice
Hexarelin targets neuroinflammatory pathways to preserve cardiac morphology and function in a mouse model of myocardial ischemia-reperfusion
Hexarelin protects cardiac H9C2 cells from angiotensin II-induced hypertrophy via the regulation of autophagy
Hexarelin attenuates atherosclerosis via inhibiting LOX-1-NF-κB signaling pathway-mediated macrophage ox-LDL uptake in ApoE(-/-) mice
Modulation of PTEN by hexarelin attenuates coronary artery ligation-induced heart failure in rats
Hexarelin treatment preserves myocardial function and reduces cardiac fibrosis in a mouse model of acute myocardial infarction
Improvement of cardiomyocyte function by in vivo hexarelin treatment in streptozotocin-induced diabetic rats
The growth hormone secretagogue hexarelin protects rat cardiomyocytes from in vivo ischemia/reperfusion injury through interleukin-1 signaling pathway
Implications of ghrelin and hexarelin in diabetes and diabetes-associated heart diseases
The cardiovascular action of hexarelin
One dose of oral hexarelin protects chronic cardiac function after myocardial infarction
Hexarelin treatment in male ghrelin knockout mice after myocardial infarction
Growth hormone secretagogues preserve the electrophysiological properties of mouse cardiomyocytes isolated from in vitro ischemia/reperfusion heart
Chronic administration of hexarelin attenuates cardiac fibrosis in the spontaneously hypertensive rat
Hexarelin suppresses high lipid diet and vitamin D3-induced atherosclerosis in the rat
Proliferative and protective effects of growth hormone secretagogues on adult rat hippocampal progenitor cells
Hexarelin suppresses cardiac fibroblast proliferation and collagen synthesis in rat
Growth hormone-releasing peptide hexarelin reduces neonatal brain injury and alters Akt/glycogen synthase kinase-3beta phosphorylation
Impact of two or three daily subcutaneous injections of hexarelin, a synthetic growth hormone (GH) secretogogue, on 24-h GH, prolactin, adrenocorticotropin and cortisol secretion in humans
Growth hormone-releasing peptides (review of hexarelin and GHRPs)
Short-term administration of intranasal or oral hexarelin does not desensitize the growth hormone responsiveness in human aging
Growth hormone-releasing activity of hexarelin in humans. A dose-response study
Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, before and during puberty
Quick Facts
- Class
- Growth Hormone Secretagogue
- Tier
- B
- Evidence
- Moderate
- Safety
- Moderate Data
- Updated
- Mar 2026
- Citations
- 27PubMed
Also known as
Tags
Peptide Families
Related Goals
Evidence Score
Clinical Trials
View Clinical TrialsLinks to ClinicalTrials.gov for reference. Listing does not imply endorsement.