Hexarelin
A potent growth hormone secretagogue peptide that also has cardioprotective properties independent of GH release.
Hexarelin is a 1990s growth hormone-releasing peptide whose real distinguishing feature is not potency but a second receptor: it binds CD36, a scavenger receptor on heart tissue and macrophages that endogenous ghrelin does not engage. Its reputation as the strongest GHRP does not survive the data — two direct human comparisons found it indistinguishable from GHRP-2 on growth hormone, prolactin, ACTH and cortisol alike, so it out-releases ipamorelin but ties its closest peer. Its growth hormone response does fade with sustained use, by roughly 45% over 16 weeks of twice-daily dosing, but that attenuation is partial and fully reverses within four weeks off, and short intermittent courses show none at all. The acute cortisol spike also fails to accumulate: over 16 weeks the cortisol area-under-curve went down, not up. The cardioprotective story is genuinely interesting and entirely preclinical — and the foundational CD36 paper actually described coronary vasoconstriction. Not approved anywhere, and banned by name as examorelin under WADA S2.2.4.
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. The widely repeated claim that hexarelin is the strongest GHRP needs qualifying: against ipamorelin it is both more potent and far less selective, but against GHRP-2 the two direct human comparisons found them indistinguishable on every axis — GH, prolactin, ACTH and cortisol alike. Where hexarelin does differ from the rest of the class is in binding the CD36 scavenger receptor, and in the fact that its GH response attenuates by roughly 45% over 16 weeks of twice-daily dosing, partially and reversibly.
History & Discovery
Hexarelin was developed in the early 1990s by Romano Deghenghi and colleagues at Europeptides in Argenteuil, France, with clinical development run by Mediolanum Farmaceutici in Milan — the two were concurrent rather than sequential, and Deghenghi sits alongside Mediolanum's Bruno Imbimbo on the author list of the first human dose-response paper in 1994. It was 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 in 2002, when a Montreal group photolabelled rat cardiac membranes with a hexarelin derivative and identified the binding protein as CD36, a scavenger receptor that endogenous ghrelin does not engage. The effect they demonstrated is worth stating precisely, because it is usually paraphrased away: hexarelin acting through CD36 raised coronary perfusion pressure in a dose-dependent manner, an effect absent in CD36-null mice, and the authors concluded CD36 may mediate the coronary vasospasm of hypercholesterolemia and atherosclerosis. Later work from the same group mapped the binding site, and showed PPAR-gamma-dependent cholesterol efflux in macrophages and mitochondrial biogenesis in white adipocytes that was lost in CD36-null animals. So CD36 engagement is well established — but it is a GHRP-6-family property rather than a hexarelin-only one, and its net cardiac valence is more mixed than the wellness framing allows. 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 acutely elevates ACTH and cortisol, to a degree overlapping with vasopressin and similar to CRH — though the mechanism is not vasopressin-mediated, since hexarelin shows no synergy with either AVP or CRH, implying a pathway at least partly independent of both. This acute effect does not persist: over 16 weeks of twice-daily dosing the cortisol area-under-curve fell rather than rose, with no change in ACTH or prolactin. 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) — though the original CD36 identification paper described a dose-dependent rise in coronary perfusion pressure, i.e. vasoconstriction, so the receptor's net cardiac effect is not uniformly protective. It is also worth noting that several of the strongest rodent cardioprotection results are attributed by their own authors to GHS-R rather than CD36: in spontaneously hypertensive rats the anti-fibrotic and blood-pressure effects were abolished by a selective GHS-R antagonist, and the ApoE-knockout atherosclerosis work credits LOX-1/NF-kB inhibition. 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 along with the acute prolactin and ACTH/cortisol activity shared across the GHRP class — matched, in direct human comparison, by GHRP-2 rather than exceeding it. Hexarelin also modulates MAPK and PI3K/Akt survival pathways, contributing to neuroprotective effects against oxidative stress in models spanning neonatal brain injury, hippocampal progenitor cells, SOD1-mutant neuroblastoma, and — per a 2026 Indian J Pharmacol study — retinal ganglion cells after optic nerve transection, extending the neuroprotection signal to the optic pathway as a novel preclinical indication.
Evidence Snapshot
Human Clinical Evidence
Moderate, and older than it looks — essentially the entire human dataset is from the 1990s. Dose-response, route comparison, head-to-head against GHRP-2, and 16-week chronic dosing studies all exist and are reasonably clean, establishing potent acute GH release, acute ACTH/cortisol release that does not accumulate chronically, and partial reversible attenuation of the GH response over months. What does not exist is any human trial with a body-composition, functional or cardiovascular endpoint, in any population, at any duration. 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, with the 2026 Celikoglu et al. J Basic Clin Physiol Pharmacol study extending the acute-lung-injury signal into an MPTP toxicity model with protective and restorative effects. Metabolic benefits (reduced fat accumulation, improved insulin sensitivity) shown in obese mice via GHS-R activation. The preclinical record is not uniformly positive, however: in a sugen/chronic-hypoxia model of pulmonary hypertension, chronic hexarelin pretreatment unexpectedly failed to prevent right-ventricular hypertrophy or cardiomyocyte relaxation impairment.
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.
- 03Desensitization is better characterized than most sources imply but still incompletely mapped. A 16-week twice-daily course produced roughly 45% attenuation that fully reversed within 4 weeks off, and 8-to-15-day intermittent courses produced none — but nothing has measured the shape of the curve between those cadences, nothing has established the minimum off-period needed for recovery, and no study has ever compared hexarelin against GHRP-2 or GHRP-6 for rate of tachyphylaxis despite that comparison being asserted everywhere.
- 04The chronic HPA question is largely answered and the answer is reassuring — 16 weeks of twice-daily dosing lowered the cortisol area-under-curve and left ACTH, prolactin, urinary free cortisol and cortisol-binding globulin unchanged — but that rests on a single small study in healthy elderly subjects at 1.5 mcg/kg. Whether it holds at the higher doses used in wellness practice, in younger users, or beyond 16 weeks, is untested.
- 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.
- 07Hexarelin's human plasma half-life has never been published. The figures in circulation are either animal values (about 76 minutes in rats, about 120 minutes in dogs) or a misreading of the GH response decay from the 1994 dose-response study, and no human pharmacokinetic comparison against other GHRPs exists.
- 08Whether CD36 engagement is net cardioprotective or net harmful is less settled than the wellness literature suggests. The paper that identified CD36 as hexarelin's cardiac target described dose-dependent coronary vasoconstriction and proposed CD36 as a mediator of coronary vasospasm, while several of the strongest rodent cardioprotection results are credited by their own authors to GHS-R or LOX-1 rather than CD36.
- 09The effect of hexarelin on IGF-1 at wellness doses is essentially uncharacterized. The available human data show no significant IGF-1 change over 8 days intranasally and only a slight rise over 15 days orally, with IGFBP-3 moving more reliably than IGF-1 — yet protocols are routinely built around an assumed IGF-1 response.
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 105–140 mcg for a 70-kg adult), administered subcutaneously two to three times daily in chronic protocols. The original clinical dose-response study (Imbimbo and colleagues, 1994, sponsored by Mediolanum Farmaceutici) gave 12 men single intravenous boluses of 0.5, 1 and 2 mcg/kg, and its numbers are the reason to stay at the low end: GH Cmax rose from 3.9 ng/mL on placebo to 26.9, 52.3 and 55.0 ng/mL across those three doses. Doubling from 1 to 2 mcg/kg bought only 2.7 ng/mL more. The calculated ED50 was 0.50 mcg/kg and the maximum achievable response 55.1 ng/mL, with the authors noting that 2 mcg/kg is already very close to maximal. Injected doses in the published human literature top out around 2 mcg/kg intravenously and 3 mcg/kg subcutaneously; milligram quantities appear only via intranasal and oral routes, where bioavailability is roughly 5% and 0.3% against 77% for subcutaneous injection.
Frequency
Hexarelin's human plasma half-life has not been published; the figures in circulation come from animal pharmacokinetics (about 76 minutes in rats, about 120 minutes in dogs) or, more often, from misreading the roughly 55-minute decay of the GH response in the 1994 dose-response study as the peptide's own half-life. There is no head-to-head pharmacokinetic comparison against GHRP-2 or GHRP-6, so claims that hexarelin lasts longer than either are unsupported. The more important pharmacodynamic constraint is attenuation of the GH response with sustained dosing. Human studies show the GH response attenuates by roughly 45% across 16 weeks of twice-daily subcutaneous dosing, recovering fully within 4 weeks off, while shorter intermittent courses show no attenuation at all. No study has compared that rate against GHRP-2 or GHRP-6. A 24-hour deconvolution study is also worth knowing for practical cadence: two and three daily injections raised integrated GH to exactly the same extent, so a third daily dose appears to add nothing. 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
The IGF-1 evidence is thinner than most protocols assume. A 24-hour study found no change in IGF-1, which is expected over that span; an 8-day intranasal course did not significantly move IGF-1 either, while a 15-day oral course produced only a slight rise (141.6 to 156.0 mcg/L). IGFBP-3 moved more reliably than IGF-1 in that work. The class-level review literature does report that prolonged GHRP administration raises IGF-1 in both animals and humans, so the direction is probably right, but no study has characterised the magnitude or time course of IGF-1 change on hexarelin at wellness doses. 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
Recovery from the attenuated GH response has been measured at one point only: four weeks after a 16-week twice-daily course, the GH response had returned to a level statistically indistinguishable from baseline. Whether it recovers sooner than that is simply unknown, so the commonly repeated claim of days to 1-2 weeks is an assumption rather than a finding — and in the one long intranasal study, in children, the blunted response had still not fully recovered three months after stopping. 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.
Monitoring & Measurement
Bloodwork & Labs
- •IGF-1 at baseline and again at 6 to 8 weeks — the standard response marker, though be aware the human evidence for an IGF-1 rise on hexarelin specifically is weak, so a flat result is not necessarily a failed protocol
- •Fasting glucose and HbA1c — GH opposes insulin action, and hexarelin's acute cortisol release compounds it
- •Morning cortisol and prolactin at baseline and once on a stable protocol. Expect the acute post-dose rise rather than a sustained elevation; the 16-week human data show cortisol exposure falling rather than rising, so a persistently high reading suggests something other than expected pharmacology
- •Thyroid panel, since uncorrected hypothyroidism blunts the GH response
- •Lipid panel if hexarelin is being used on the strength of its CD36 and cholesterol-efflux pharmacology — that rationale is entirely preclinical, and your own lipids are the only readout you will actually have
Functional & Performance Tests
- •DEXA for lean and fat mass, worth doing precisely because no human trial has ever measured a body-composition endpoint for hexarelin
- •Resting blood pressure and heart rate, given that the foundational CD36 work describes coronary vasoconstriction rather than vasodilation
- •Grip strength or a similar simple measure, to separate fluid retention from genuine change
When to Test
Draw baseline IGF-1, fasting glucose, HbA1c, morning cortisol, prolactin and a lipid panel before starting, then recheck at 6 to 8 weeks. Cortisol and prolactin should be drawn at least several hours after the last dose if the question is chronic exposure rather than the acute post-injection spike — sampling 30 to 60 minutes after an injection will capture a rise that is expected and not informative.
Interpretation & Notes
The single most useful framing is that hexarelin's human evidence base ends at biochemistry. Every endpoint anyone actually wants — body composition, recovery, cardiac protection — has been measured only in animals, so personal before-and-after data is the only evidence that will ever exist for an individual user. Interpreting cortisol requires knowing when the sample was drawn: a single dose produces an ACTH and cortisol rise comparable to a dose of vasopressin, but across 16 weeks of twice-daily dosing cortisol exposure went down rather than up, so the chronic-hypercortisolism concern that dominates discussion of this peptide is not supported by the one study that looked for it.
Common Questions
How does hexarelin compare to other GHRPs?
Against ipamorelin, hexarelin releases more GH but is much less selective — ipamorelin is the GHS that largely spares ACTH and cortisol. Against GHRP-2 the honest answer is that they are equivalent, and the common claim that hexarelin is stronger does not survive contact with the data. Two direct human comparisons from the same group found matched GH responses at both 1 and 2 mcg/kg, and at 2 mcg/kg the numbers are nearly interchangeable: GH Cmax 77.3 vs 74.1 mcg/L, prolactin 14.9 vs 12.3 mcg/L, ACTH 48.0 vs 51.4 pg/mL and cortisol 179.9 vs 181.2 mcg/L for hexarelin and GHRP-2 respectively. What genuinely distinguishes hexarelin is CD36 binding, which underlies its cardiovascular pharmacology.
Does hexarelin desensitize with repeated use?
Partially, reversibly, and more slowly than the usual advice implies — and the dosing pattern matters more than the molecule. The one study that ran long enough to answer this gave 12 healthy elderly adults twice-daily subcutaneous hexarelin for 16 weeks: the GH response fell from an area-under-curve of 19.1 at baseline to 12.3 at week 4 and 10.5 at week 16, roughly a 45% attenuation, and then returned to 19.4 — statistically indistinguishable from baseline — after just four weeks off. The authors concluded the attenuation is partial and reversible. Intermittent dosing may not desensitize at all: 8-day intranasal and 15-day oral courses in elderly subjects left the acute GH response fully intact. Against that, long-term intranasal dosing in children blunted the GH peak within 7 days and had not fully recovered 3 months after stopping, though their growth velocity still improved throughout. There is no head-to-head evidence that hexarelin desensitizes faster than GHRP-2; that comparison is asserted in the wellness literature rather than measured.
How does hexarelin protect the heart?
Hexarelin binds the CD36 scavenger receptor on cardiac tissue independently of its GH-releasing action. This activates PPARgamma signaling, reduces fibrosis, protects cardiomyocytes from apoptosis (e.g., from angiotensin II or doxorubicin), and promotes cholesterol efflux in macrophages to counter atherosclerosis.
Is hexarelin banned in sports?
Yes. Hexarelin is explicitly prohibited under WADA's S2.2.4 (growth hormone releasing factors), which names it as examorelin (hexarelin), at all times, both in and out of competition. WADA-accredited labs have validated LC-MS/MS urinary detection methods for hexarelin and its metabolites — peptide structure does not equal undetectability. Athletes subject to WADA, USADA, UKAD, or equivalent bodies must avoid it.
Does hexarelin raise cortisol and prolactin?
Acutely yes, chronically no — and not more than GHRP-2. A single dose raises ACTH and cortisol to about the same degree as a dose of vasopressin and similar to CRH, which is a real effect. But the mechanism is not what is usually claimed: the study that specifically tested it found hexarelin had no synergistic interaction with either vasopressin or CRH, while those two synergized with each other as expected, leading the authors to conclude that the ACTH-releasing action of GHRPs is at least partly independent of both pathways. The page-level claim that hexarelin works through vasopressin confuses overlapping in magnitude with acting through. More practically, the acute rise does not persist. Over 16 weeks of twice-daily dosing the cortisol area-under-curve actually fell from 1506 to 1222 nmol/L/h and recovered after stopping, with no change in ACTH, prolactin, urinary free cortisol or cortisol-binding globulin; the authors concluded that over-stimulation of the pituitary-adrenal axis and prolactin secretion do not occur on this regimen. A 24-hour study found the same direction — prior hexarelin abolished the ACTH and cortisol response to a later challenge while only blunting the GH response.
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 acute cortisol release further antagonizes glycemic control, which makes this more pointed than for ipamorelin — though in direct comparison GHRP-2 behaves the same way.
- •Active hypercortisolism, Cushing's disease, or poorly controlled HPA-axis disorders — hexarelin acutely stimulates ACTH and cortisol to a degree comparable with vasopressin, and although this does not accumulate over months of dosing in healthy adults, unmasking or worsening existing HPA-axis pathology remains a theoretical 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 acutely elevates cortisol where ipamorelin largely does not, this interaction is more relevant than for ipamorelin — though not more so than for GHRP-2, which matches hexarelin on cortisol in head-to-head testing. 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
- • Partial, reversible attenuation of the GH response with sustained use — roughly 45% over 16 weeks of twice-daily dosing, recovering within 4 weeks off
- • Acute ACTH and cortisol release comparable to a dose of vasopressin, though it does not accumulate with chronic dosing
- • Equivalent to GHRP-2 on cortisol and prolactin in direct human comparison — less selective than ipamorelin, not more so than its closest peer
- • 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 is not on the 503A Bulks List, and as of FDA's May 2026 lists it does not appear in any of the 503A nomination categories (1, 2 or 3) or on FDA's Category 2 safety-risk list. 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 S2.2.4 (growth hormone releasing factors), which names examorelin (hexarelin) among the GH-releasing peptides — 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
The premise is shakier than it sounds. Hexarelin clearly out-releases ipamorelin, but against GHRP-2 — its closest peer and the usual comparison — two direct human trials found matched GH responses at 1 and 2 mcg/kg and matched prolactin, ACTH and cortisol responses as well. So hexarelin is not the strongest GHRP; it is tied. Even setting that aside, 'strongest' is not a synonym for 'best': acute pulse amplitude is not the same thing as sustained IGF-1 elevation, and hexarelin's GH response attenuates by roughly 45% over 16 weeks of twice-daily use. Its real distinguishing feature is not potency but CD36 binding.
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
Half right. Hexarelin does engage CD36, a scavenger receptor distinct from GHS-R1a, and endogenous ghrelin does not — that part is real and genuinely sets it apart from the natural ligand. But CD36 binding is a property of the GHRP-6 chemical family rather than of hexarelin alone: hexarelin is itself a GHRP-6 analogue, and a 2011 structure-activity study found a GHRP-6 azapeptide binding CD36 somewhat more tightly than hexarelin does (1.34 versus 2.37 micromolar). The foundational paper is titled for the class, not the molecule. The defensible claim is that hexarelin is the best-studied CD36-binding GHRP, not the only one.
Myth
Hexarelin desensitization is overstated — you can dose it continuously like the other GHRPs.
Reality
Attenuation is real but the usual framing overstates it, and the page used to as well. The 16-week study that actually measured it found a roughly 45% fall in the GH response that was fully recovered four weeks after stopping — the authors called it partial and reversible. Intermittent courses of 8 to 15 days did not desensitize at all. And no study has ever compared hexarelin against GHRP-2 for rate of tachyphylaxis, so the claim that it desensitizes faster than its peers is unsourced. Cycling is reasonable on this evidence; the specific claim that hexarelin desensitizes uniquely fast is not.
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, and it is named explicitly on the Prohibited List as examorelin under S2.2.4 in both the 2026 and 2027 Lists. A short plasma half-life does not equal undetectability — metabolites remain measurable for a window after dosing. We have not been able to locate a published anti-doping decision naming hexarelin specifically, so the honest statement is that the detection methods exist and the substance is banned by name, not that there is a public catalogue of hexarelin cases.
Published Research
44 studiesHistopathological and immunohistochemical characterization of MPTP-associated pancreatic injury and its attenuation by Hexarelin in mice
Protective and restorative effects of hexarelin on MPTP-induced lung injury in mice.
The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.
Hexarelin promotes the survival of retinal ganglion cells after optic nerve transection
The newest neuroprotection result, extending the signal to the optic pathway. In golden hamsters after optic nerve transection, five days of once-daily hexarelin raised 7-day retinal ganglion cell survival dose-dependently from 51.2% on saline to 62.4%, 68.5% and 74.6% at 25, 50 and 100 mcg/kg. Twice-daily dosing did better still, reaching 91.4% at 100 mcg/kg and 109.2% at 150 mcg/kg against 72.9% for saline.
Protective 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 the fat accumulation and improves the 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
Three months of daily hexarelin in high-fat-fed ApoE-knockout mice lowered total cholesterol, triglycerides and LDL-c, raised HDL-c, and reduced plaque and neointimal area by suppressing macrophage uptake of oxidized LDL. As with the hypertensive-rat work, the authors attribute the effect to LOX-1 and NF-kB signalling and report increased GHSR expression, rather than to CD36 — a reminder that the page's CD36-centred framing is cleaner than the underlying literature.
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
One of the strongest post-infarct results in the hexarelin literature. Mice given hexarelin for 21 days after coronary artery ligation showed improved left-ventricular function on MRI and reduced LV mass, interstitial collagen, TGF-beta1, myofibroblast differentiation, troponin-I, IL-1beta and TNF-alpha. It is also a clean illustration of the page's central caveat: this is a mouse infarct model, and nothing equivalent has been attempted in humans.
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
The anchor review for hexarelin's dual-receptor story, and the best single entry point to the cardiovascular literature. It sets out GHS-R1a expression across brain and periphery alongside the finding that the non-GHSR receptor CD36 acts as a specific cardiac receptor for hexarelin, and notes that hexarelin is chemically more stable and functionally more potent than endogenous ghrelin.
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
Five weeks of hexarelin in spontaneously hypertensive rats reduced interstitial and perivascular collagen, raised MMP-2 and MMP-9, lowered TIMP-1, and attenuated left-ventricular hypertrophy, diastolic dysfunction and blood pressure. The detail that matters for mechanism: all of these effects were abolished by a selective GHS-R antagonist, so this particular cardioprotective result is attributed by its own authors to the ghrelin receptor rather than to CD36.
Structure-activity relationships of GHRP-6 azapeptide ligands of the CD36 scavenger receptor by solid-phase submonomer azapeptide synthesis
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
A growth hormone-releasing peptide promotes mitochondrial biogenesis and a fat burning-like phenotype through scavenger receptor CD36 in white adipocytes
A growth hormone-releasing peptide that binds scavenger receptor CD36 and ghrelin receptor up-regulates sterol transporters and cholesterol efflux in macrophages through a peroxisome proliferator-activated receptor gamma-dependent pathway
Growth hormone-releasing peptide hexarelin reduces neonatal brain injury and alters Akt/glycogen synthase kinase-3beta phosphorylation
Identification of the growth hormone-releasing peptide binding site in CD36: a photoaffinity cross-linking study
CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart
The paper that identified hexarelin's non-GHSR cardiac target. Rat cardiac membranes labelled with a photoactivatable hexarelin derivative yielded an 84 kDa binding protein whose N-terminal sequence was identical to rat CD36. The functional effect is more double-edged than the usual summary suggests: hexarelin raised coronary perfusion pressure dose-dependently — vasoconstriction — and the effect was absent in CD36-null mice and CD36-deficient hypertensive rats, leading the authors to propose CD36 as a mediator of the coronary vasospasm seen in hypercholesterolemia and atherosclerosis. Note also that the title names the GHRP class, not hexarelin alone.
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
A 24-hour deconvolution study in 6 young men at 1.5 mcg/kg subcutaneously, with blood sampled every 20 minutes — the most granular picture of what a day of hexarelin actually does. Two and three daily injections raised integrated 24-hour GH to the same extent, amplifying secretory burst mass rather than burst frequency, which suggests a third daily dose adds nothing. No change occurred in IGF-I, prolactin, ACTH or cortisol secretion across the day. A terminal intravenous challenge showed partial down-regulation of GH but complete abolition of the ACTH and cortisol response, meaning the stress-axis effect desensitizes faster and more completely than the GH effect.
Does desensitization to hexarelin occur?
The only study long enough to answer the cycling question, and the source for everything defensible said about hexarelin tachyphylaxis. Twelve healthy elderly adults received twice-daily subcutaneous hexarelin for 16 weeks; the GH area-under-curve fell from 19.1 at baseline to 13.1 at week 1, 12.3 at week 4 and 10.5 at week 16 — roughly 45% attenuation. Four weeks after stopping, a rechallenge returned it to 19.4, statistically indistinguishable from baseline. The authors' conclusion is the key phrase: attenuation after long-term hexarelin therapy is partial and reversible.
Kinetics and disposition of hexarelin, a peptidic growth hormone secretagogue, in rats
The effect of chronic hexarelin administration on the pituitary-adrenal axis and prolactin
The direct test of whether hexarelin's acute cortisol spike accumulates into a chronic problem. Over 16 weeks of twice-daily subcutaneous dosing, the cortisol area-under-curve fell from 1506 to 1222 nmol/L/h and rebounded to 1586 four weeks after stopping, with no significant change in ACTH, prolactin, 24-hour urinary free cortisol or cortisol-binding globulin. The authors concluded that on this regimen over-stimulation of the pituitary-adrenal axis and prolactin secretion do not occur — which is the opposite of how chronic hexarelin is usually described.
Tyr-Ala-Hexarelin, a synthetic octapeptide, possesses the same endocrine activities of Hexarelin and GHRP-2 in humans
Hexarelin, a synthetic growth-hormone releasing peptide, shows no interaction with corticotropin-releasing hormone and vasopressin on adrenocorticotropin and cortisol secretion in humans
The study that tested whether hexarelin works through vasopressin, and found it does not. In 7 volunteers, hexarelin raised ACTH and cortisol to levels overlapping vasopressin and similar to CRH — but co-administering hexarelin with vasopressin produced no significant interaction, while CRH and vasopressin synergized with each other as expected. The authors concluded the ACTH-releasing activity of GHRPs is at least partly independent of both CRH- and vasopressin-mediated pathways. 'Overlapping in magnitude with vasopressin' is routinely misread as 'acting via vasopressin'.
Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Comparison with the effects of GHRH, TRH and hCRH
The direct human comparison that undercuts hexarelin's reputation as the strongest GHRP. In 6 young adults given 1 and 2 mcg/kg intravenously, GHRP-2 and hexarelin produced a similar strong GH response at both doses, and similar increases in prolactin, ACTH and cortisol. The authors also calibrated the off-target effects against reference hormones: the GHRPs' ACTH and cortisol release is comparable to CRH, while their prolactin release is lower than TRH. Note that Deghenghi, hexarelin's inventor, is a co-author.
Growth hormone-releasing peptides
Short-term administration of intranasal or oral Hexarelin, a synthetic hexapeptide, does not desensitize the growth hormone responsiveness in human aging
The counterweight to the assumption that hexarelin desensitizes quickly. Elderly subjects received either 8 days of intranasal hexarelin (about 18 mcg/kg three times daily) or 15 days of oral hexarelin (about 300 mcg/kg three times daily). The acute GH response was fully maintained in both arms — in fact trending upward intranasally, from 229.4 to 342.5 mcg/L/h — and neither route changed prolactin or cortisol or produced any side effect. The authors concluded that chronic but intermittent treatment does not desensitize the GH response, framing cadence rather than the molecule as the variable that matters.
Desensitization from long-term intranasal treatment with hexarelin does not interfere with the biological effects of this growth hormone-releasing peptide in short children
Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man
Growth hormone-releasing activity of hexarelin in humans. A dose-response study
The first human dose-response trial, and the origin of the standard dosing range. Twelve adult men received single intravenous boluses of 0.5, 1 and 2 mcg/kg against placebo in a double-blind rising-dose design. Peak GH rose from 3.9 ng/mL on placebo to 26.9, 52.3 and 55.0 ng/mL — note that doubling the dose from 1 to 2 mcg/kg added only 2.7 ng/mL. The calculated ED50 was 0.50 mcg/kg for peak GH and the maximum achievable response 55.1 ng/mL, with the authors stating that 2 mcg/kg is already very close to maximal. The roughly 55-minute figure in this abstract describes the decay of the GH response, not hexarelin's own plasma half-life, and is frequently misquoted as the latter.
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
- Nov 2026
- Citations
- 44PubMed
Also known as
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Peptide Families
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Evidence Score
Clinical Trials
View Clinical TrialsLinks to ClinicalTrials.gov for reference. Listing does not imply endorsement.