GHRP-6

GHRP-6 at a Glance

GHRP-6 is the original growth-hormone-releasing peptide, the compound that revealed the ghrelin receptor existed before ghrelin itself was discovered. It remains a validated reagent for GH-stimulation testing, which makes it the least speculative peptide in this family — its ability to provoke growth hormone is not in question. It is also the most strongly appetite-stimulating of the group, a property that dominates real-world use as much as the GH effect does. It is unapproved as a therapeutic.

History & Development

GHRP-6 is the original growth-hormone-releasing peptide - the compound the whole class descends from, and the least selective member of it.

First described	Not established in the sources consulted for this section
Discovered / synthesised by	Not established in the sources consulted for this section
Institution	Not established in the sources consulted for this section
Origin	Synthetic hexapeptide; ghrelin-receptor (GHS-R1a) agonist
Key patent	Not established in the sources consulted for this section
Assignee	Not established in the sources consulted for this section
Development status	Established as a GH-stimulation-test reagent; never approved as a therapy

Discovery

GHRP-6 came first, and its existence is what revealed that the pituitary carries a receptor for something other than GHRH - the receptor later identified as the ghrelin receptor, years before ghrelin itself was found. The peptide effectively predicted its own endogenous ligand.

Its lack of selectivity is its defining property. Alongside growth hormone it raises cortisol, prolactin and hunger - the appetite effect being pronounced enough to define the user experience. Every later secretagogue in this family, ipamorelin especially, was designed to keep the GH release and drop the rest.

Development & ownership

GHRP-6’s established role is as a validated reagent for GH-stimulation testing - a diagnostic tool, not a therapy.

Its human evidence should be read for what it is: essentially every study measures GH concentration in blood, over a couple of hours, in a handful of volunteers. Those are pharmacodynamic demonstrations that the compound does what it says, not evidence of any clinical outcome. The effect is short-lived and attenuates with repetition.

The most active therapeutic research line is cardiac and entirely preclinical - including work in 26 dogs with pacing-induced dilated cardiomyopathy, where two weeks of subcutaneous GHRP-6 enhanced systolic function.

How it reached the market

GHRP-6 has never been approved as a therapy anywhere. It is sold as a research peptide for muscle gain and recovery, where its hallmark side effect - intense hunger - is often reframed as a benefit for bulking rather than as the off-target cost it represents.

What It's Used For

GHRP-6 is a synthetic hexapeptide — His-D-Trp-Ala-Trp-D-Phe-Lys-NH₂, about 873 Da — and it matters first as a piece of scientific history rather than as a therapy. Cyril Bowers’ group at Tulane built it in the 1980s from opioid-peptide fragments, and it became the pharmacological probe that revealed a growth-hormone-releasing pathway separate from GHRH ^{3Reference 3Bowers CY · 1993GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing)View study →}.

That receptor was named the growth-hormone-secretagogue receptor (GHS-R1a) after the drug that found it; the body’s own ligand for it, ghrelin, was not identified until 1999 — more than a decade later ^{25Reference 25Anderson LL et al. · 2005ReviewPhysiology of ghrelin and related peptides — reviewView study →}.

So GHRP-6 is the compound that led to the discovery of a hormone. That is a genuine and unusual pedigree, and it is worth being clear about what it is: a discovery story, not clinical evidence. GHRP-6 has never been approved as a medicine or a dietary supplement in any country, and no outcome trial has ever been completed for it.

What human data exist are almost entirely acute GH-pulse pharmacology in small volunteer groups from the 1990s and early 2000s, plus a body of diagnostic-test work in which GHRP-6 (usually combined with GHRH) served as a provocative stimulus for diagnosing adult growth-hormone deficiency ^{6,7,8Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →Reference 7Petersenn S et al. · 2002Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test — human (diagnostic comparison)View study →Reference 8Cordido F et al. · 2003Clinical trialComparison between insulin tolerance test, GHRH, GHRH plus acipimox and GHRH plus GHRP-6 for the diagnosis of adult GH deficiency in normal subjects, obese and hypopituitary patients — human (clinical trial)View study →}.

That is a reagent’s paper trail, not a drug’s. The therapeutic lines that look most active today — cardioprotection, multi-organ cytoprotection — are animal and in-vitro only, and are concentrated in a single development program (Cuba’s CIGB, with Chinese collaborators, advancing GHRP-6 as CIGB-500) that remains preclinical ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}.

Route is worth noting because it cuts against the usual peptide rule: GHRP-6 releases GH in humans by intravenous, subcutaneous, intranasal and oral administration ^{3,5Reference 3Bowers CY · 1993GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing)View study →Reference 5Bellone J et al. · 1995Clinical trialGrowth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric)View study →}, though oral requires far larger doses.

The property that actually distinguishes GHRP-6 from its successors is non-selectivity. It is the least selective of the GHRPs: in humans it raises ACTH and cortisol alongside GH ^{9,10Reference 9Alaioubi B et al. · 2010Clinical trialDiagnosis of adrenal insufficiency using the GHRP-6 test: comparison with the insulin tolerance test in patients with hypothalamic-pituitary-adrenal disease — human (clinical trial)View study →Reference 10de Sá LB et al. · 2010Effects of ghrelin, growth hormone-releasing peptide-6, and growth hormone-releasing hormone on growth hormone, adrenocorticotropic hormone, and cortisol release in type 1 diabetes mellitus — human (controlled study, n=18)View study →}, it carries the class prolactin rise, and it is a powerful appetite stimulant. Ipamorelin was specifically engineered to strip those off-target effects out, and that is precisely why GHRP-6 fell out of favor. Note the direction of the appetite effect, because it is the opposite of what most of this hub’s metabolic compounds do: the incretin drugs (semaglutide, tirzepatide) suppress appetite. GHRP-6 drives it up.

Evidence by IndicationStrength of support · Beta

Support is an experimental score I’m building — a composite weighted by study type (human > animal > in vitro > review) and study volume. It’s a beta: a fast way to rank strength of evidence at a glance, not a validated metric.

Read the low scores carefully here, because they mean “never tested,” not “tested and failed.” GHRP-6 has essentially no negative human data — but it also has no positive human outcome data, for anything. Every human study here measures a hormone level or a diagnostic cut-off, and every therapeutic claim below the top two rows is preclinical. A high score on the diagnostic row is a score for a laboratory test, not for a treatment. Each application links down to its write-up.

01GH-deficiency diagnostic testingPromising62%Replicated human diagnostic-accuracy studies against the insulin-tolerance test, incl. a 250-subject Lancet multicenter study — but a reagent, never an approved product, now superseded ^{6,7,8Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →Reference 7Petersenn S et al. · 2002Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test — human (diagnostic comparison)View study →Reference 8Cordido F et al. · 2003Clinical trialComparison between insulin tolerance test, GHRH, GHRH plus acipimox and GHRH plus GHRP-6 for the diagnosis of adult GH deficiency in normal subjects, obese and hypopituitary patients — human (clinical trial)View study →}

02Acute GH release (endocrine pharmacology)Promising48%Human acute pharmacodynamics across four routes + resolved somatotroph mechanism. Biomarker only; effect is transient ^{1,3,4,5Reference 1Lei T et al. · 1995In vitroGrowth hormone releasing peptide (GHRP-6) stimulates phosphatidylinositol (PI) turnover in human pituitary somatotroph cells — in vitro (human pituitary tumour cells)View study →Reference 3Bowers CY · 1993GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing)View study →Reference 4Adams EF et al. · 1996In vitroProtein kinase C-dependent growth hormone releasing peptides stimulate cyclic adenosine 3’,5’-monophosphate production by human pituitary somatotropinomas — in vitro (human pituitary tumour cells)View study →Reference 5Bellone J et al. · 1995Clinical trialGrowth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric)View study →}

03CardioprotectionShaky38%Replicated animal (dog, rat) + CD36 mechanism; dominated by one development program; zero human data ^{15,16,17,24Reference 15Shen YT et al. · 2003A growth hormone secretagogue prevents ischemic-induced mortality independently of the growth hormone pathway in dogs with chronic dilated cardiomyopathy — animal (dog, n=26)View study →Reference 16Berlanga-Acosta J et al. · 2024AnimalGrowth hormone releasing peptide-6 (GHRP-6) prevents doxorubicin-induced myocardial and extra-myocardial damages by activating prosurvival mechanisms — animal (rat)View study →Reference 17Wang L et al. · 2026AnimalGrowth hormone-releasing peptide-6 (GHRP-6) ameliorates post-infarct ventricular remodeling and systolic dysfunction in a model of permanent coronary ligation — animal (rat)View study →Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}

04Appetite stimulationShaky30%Strong, replicated rat food-intake and hypothalamic-activation data ^{12,13Reference 12Lawrence CB et al. · 2002AnimalAcute central ghrelin and GH secretagogues induce feeding and activate brain appetite centers — animal (rat, intracerebroventricular)View study →Reference 13Tung YL et al. · 2004AnimalGlucocorticoid-dependent stimulation of adiposity and appetite by a ghrelin mimetic in the rat — animal (rat)View study →}. Human effect is a class inference — no human food-intake or cachexia trial exists

05Multi-organ cytoprotectionShaky26%Animal and in-vitro injury models (gut, liver, lung, kidney), CD36-linked, same program ^{18,19,20Reference 18Cibrián D et al. · 2006In vitroUse of growth-hormone-releasing peptide-6 (GHRP-6) for the prevention of multiple organ failure — animal (rat) and in vitroView study →Reference 19Wang L et al. · 2026AnimalGrowth hormone releasing peptide-6 (GHRP-6) ameliorates acute lung injury and its subsequent evolvement to interstitial fibrosis — animal (mouse)View study →Reference 20Zhao X et al. · 2025AnimalGrowth hormone-releasing peptide 6 (GHRP-6) hydrogel for acute kidney injury therapy via metabolic regulation — animal (rodent)View study →}

06Metabolic weight and fat gainShaky22%Rat-only; effect is conditional on insulin/glucose and glucocorticoid status ^{13,14Reference 13Tung YL et al. · 2004AnimalGlucocorticoid-dependent stimulation of adiposity and appetite by a ghrelin mimetic in the rat — animal (rat)View study →Reference 14Granado M et al. · 2010AnimalThe positive effects of growth hormone-releasing peptide-6 on weight gain and fat mass accrual depend on the insulin/glucose status — animal (rat)View study →}

07Oocyte in-vitro maturationShaky16%Single human in-vitro (cultured oocyte) study; nuclear maturation improved, cytoplasmic maturation not ^{26Reference 26Ostadian C et al. · 2025In vitroAssessing the effectiveness of growth hormone releasing protein-6 in improving human oocyte maturation and meiotic progression in in vitro maturation culture media — in vitro (human oocytes)View study →}

Mechanisms

Pharmacokinetics

Route is unusually permissive for a peptide, and this is a real distinction. GHRP-6 releases GH in humans after intravenous, subcutaneous, intranasal and oral administration ^{3Reference 3Bowers CY · 1993GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing)View study →} — the last of these is genuinely notable, since almost every other peptide on this hub is destroyed by digestion. But oral bioavailability is poor enough that the doses diverge by orders of magnitude: diagnostic testing uses 1 µg/kg intravenously ^{6Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →}, while the pediatric oral study needed 300 µg/kg ^{5Reference 5Bellone J et al. · 1995Clinical trialGrowth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric)View study →}. So “orally active” is true and misleading at the same time — it does not make an oral product practical.

The GH-releasing effect is short: GH peaks within roughly 30–60 minutes and returns toward baseline within about two hours, and the response attenuates with frequent repeated dosing (tachyphylaxis) — a key reason GHRP-6 never became a chronic therapy and why its entire human record is acute-probe-shaped. A dedicated human plasma half-life has not been established in the primary literature located in this pass; it is best described as short, on the order of tens of minutes, and the specific figures circulating on vendor sites are not traceable to a primary source. None is invented here. GHRP-6 also has documented non-pituitary actions — the acute insulin and glucose rise seen under GH-receptor blockade was attributed to direct effects on the gastroentero-hepatic axis rather than to GH ^{11Reference 11Muller AF et al. · 2001RCTBlockade of the growth hormone (GH) receptor unmasks rapid GH-releasing peptide-6-mediated tissue-specific insulin resistance — human (double-blind, placebo-controlled, n=10)View study →} — so its pharmacodynamics are not fully captured by the GH curve.

Gray-market supply is lyophilized powder requiring reconstitution by the user, typically with bacteriostatic water, and injected subcutaneously; reconstituted solution must be refrigerated and is short-lived. Reconstitution and stability parameters in that channel are vendor claims, not independently documented. The CIGB-500 development formulation is given intravenously ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}.

Clinical & regulatory status

GHRP-6 is an unapproved research chemical. It has never been approved as a drug or a dietary supplement by the FDA, EMA, TGA or any other regulator, in any country, for any indication — including the diagnostic use it was validated for. Its legitimate human history is entirely as an investigational diagnostic and pharmacological probe from the 1990s and 2000s, predating trial-registration mandates; that diagnostic role has since been filled by macimorelin, an approved oral GH-secretagogue test. As a growth-hormone secretagogue it is prohibited in sport at all times under the WADA Prohibited List (class S2). In the consumer market it is sold “for research use only / not for human consumption.”

A direct query of the ClinicalTrials.gov API in this pass returned zero registered studies for GHRP-6, for CIGB-500, and for “growth hormone releasing peptide-6” as an intervention or term. There is no completed trial, no ongoing trial and no terminated trial to report — the compound has never entered the modern registered-trial system at all. The only live therapeutic development is CIGB’s CIGB-500 program for myocardial infarction, which remains in preclinical toxicology ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}.

Last checked: July 2026.

Sourcing, Route & Legal Status

Regulatory status. GHRP-6 is not approved anywhere, for anything — not as a medicine, not as a dietary supplement, and not (despite its validated performance as a test reagent) as a diagnostic product. It is not a scheduled or controlled substance in the US, but “not scheduled” is not “approved”: marketing it for human consumption is unlawful in most Western jurisdictions, which is why it is sold as a research chemical labeled not for human consumption — a labeling convention that shifts liability to the buyer and provides no quality assurance whatsoever. It is banned in sport at all times under WADA class S2 and is a routine target in doping-control assays. The one active therapeutic-development effort, Cuba’s CIGB with Chinese collaborators developing GHRP-6 as CIGB-500, is preclinical and not marketed ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}.

How it’s supplied and administered. Gray-market GHRP-6 arrives as a lyophilized (freeze-dried) powder in a multi-dose vial, commonly 5–10 mg, which the buyer reconstitutes with bacteriostatic or sterile water before subcutaneous injection. Lyophilized powder is stored refrigerated or frozen and protected from light; reconstituted solution is unstable and must be refrigerated and used quickly. The short duration of the GH pulse is why community protocols involve repeated daily injections — a pattern no study has ever evaluated. Although GHRP-6 is one of the few peptides here with genuine oral activity ^{3,5Reference 3Bowers CY · 1993GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing)View study →Reference 5Bellone J et al. · 1995Clinical trialGrowth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric)View study →}, the dose penalty is large enough that oral products are not a practical route, and any oral product’s actual content is unverifiable.

Sourcing reality (this is a safety issue, not a footnote). Every gray-market vial comes from an unregulated supplier with no manufacturing oversight. There is no assurance of identity, correct sequence, peptide content, freedom from synthesis impurities, or absence of bacterial endotoxin — the last of which matters acutely for an injected product, where contamination can cause fever, injection-site reactions or systemic illness. Mislabeling, under- and over-filling and outright substitution are documented problems across the research-peptide market. A specific hazard for this compound is substitution within its own class: GHRP-6, GHRP-2 and hexarelin are closely related hexapeptides with different selectivity profiles, and a buyer has no way to distinguish them without independent analysis. Third-party certificates of analysis — mass-spectrometry identity, HPLC purity and endotoxin testing — are the minimum needed to interpret the risk, and even those are only as trustworthy as whoever commissioned them. This page does not recommend or link vendors; gray-market peptide identity and purity cannot be assumed.

Safety

No human study of GHRP-6 has ever run beyond a single acute dose, so nothing here is a long-term safety record. Its defining liability is non-selectivity — it raises ACTH, cortisol and prolactin alongside growth hormone, which is precisely what the later secretagogues were engineered to avoid.

Safety at a Glance

❔ Toxicity unknownDrug interactions

• The least selective of the GH secretagogues. It stimulates the stress axis every time it is dosed, and nobody has studied what chronic exposure does.
• Measured metabolic effect in humans. A roughly eight-fold acute rise in insulin and a rise in glucose under GH-receptor blockade.
• Several groups should not use it at all. Active or prior malignancy, diabetes, adrenal or pituitary disease, children and adolescents, and anyone pregnant or breastfeeding.
• Long-term safety is unstudied, not reassuring. The longest controlled data of any kind is a 28-day intravenous study in dogs.
• Strong hunger is the practical ceiling. In rodents that appetite effect translates into increased fat mass — the opposite of the intended use.
• Unregulated injected product. Injection-site reactions, non-sterile technique, endotoxin exposure and self-mixed dosing error.

Full Safety & Interactions Detail

Overall posture. No human study of GHRP-6 has ever run longer than a single acute dose. Within that narrow window it was well tolerated: the 250-subject diagnostic study reported no side-effects from a 1 µg/kg intravenous dose combined with GHRH ^{6Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →}, and the equivalent doses in the other diagnostic studies were similarly uneventful ^{7,8,9Reference 7Petersenn S et al. · 2002Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test — human (diagnostic comparison)View study →Reference 8Cordido F et al. · 2003Clinical trialComparison between insulin tolerance test, GHRH, GHRH plus acipimox and GHRH plus GHRP-6 for the diagnosis of adult GH deficiency in normal subjects, obese and hypopituitary patients — human (clinical trial)View study →Reference 9Alaioubi B et al. · 2010Clinical trialDiagnosis of adrenal insufficiency using the GHRP-6 test: comparison with the insulin tolerance test in patients with hypothalamic-pituitary-adrenal disease — human (clinical trial)View study →}. That is a real observation about single microgram-per-kilogram doses in a clinic, and it is not evidence about repeated self-injection at gray-market doses, which has never been studied at all. Do not let “well tolerated in a stimulation test” stand in for chronic use.

The defining liability is non-selectivity. GHRP-6 is the least selective of the growth-hormone secretagogues, and this is the single most decision-relevant safety fact on the page. In humans, GHRP-6 releases ACTH and cortisol alongside GH — reliably enough that it has been used as a deliberate provocative test of the hypothalamic-pituitary-adrenal axis ^{9,10Reference 9Alaioubi B et al. · 2010Clinical trialDiagnosis of adrenal insufficiency using the GHRP-6 test: comparison with the insulin tolerance test in patients with hypothalamic-pituitary-adrenal disease — human (clinical trial)View study →Reference 10de Sá LB et al. · 2010Effects of ghrelin, growth hormone-releasing peptide-6, and growth hormone-releasing hormone on growth hormone, adrenocorticotropic hormone, and cortisol release in type 1 diabetes mellitus — human (controlled study, n=18)View study →}. A prolactin rise is a recognized effect across the GHRP class. This is exactly the profile ipamorelin was engineered to eliminate, and it means GHRP-6 is not a clean GH tool: anyone using it is also intermittently stimulating the stress axis. Repeated activation of cortisol secretion is not a trivial background effect, and no study has characterized what chronic dosing does to it.

Appetite as a dose-limiting effect. Strong hunger is the effect users report most consistently and the practical tolerability ceiling for most of them. It is well demonstrated in rats ^{12,13Reference 12Lawrence CB et al. · 2002AnimalAcute central ghrelin and GH secretagogues induce feeding and activate brain appetite centers — animal (rat, intracerebroventricular)View study →Reference 13Tung YL et al. · 2004AnimalGlucocorticoid-dependent stimulation of adiposity and appetite by a ghrelin mimetic in the rat — animal (rat)View study →} and mechanistically inevitable for a ghrelin-receptor agonist, but note that for anyone using GHRP-6 for body composition, the rodent data show the hunger translating into increased fat mass ^{13,14Reference 13Tung YL et al. · 2004AnimalGlucocorticoid-dependent stimulation of adiposity and appetite by a ghrelin mimetic in the rat — animal (rat)View study →Reference 14Granado M et al. · 2010AnimalThe positive effects of growth hormone-releasing peptide-6 on weight gain and fat mass accrual depend on the insulin/glucose status — animal (rat)View study →} — the opposite of the intended effect.

Metabolic effects. GHRP-6 acutely raised serum insulin roughly eight-fold and raised glucose in healthy men under GH-receptor blockade, an effect attributed to direct non-pituitary action ^{11Reference 11Muller AF et al. · 2001RCTBlockade of the growth hormone (GH) receptor unmasks rapid GH-releasing peptide-6-mediated tissue-specific insulin resistance — human (double-blind, placebo-controlled, n=10)View study →}. Separately, the GH class carries recognized effects on insulin sensitivity and glucose handling and on fluid balance (edema, arthralgia and carpal-tunnel-type symptoms are characteristic of GH excess). The human GHRP-6 finding is measured; the class effects are mechanistic inference and are labeled as such.

Animal toxicology. A 28-day repeated-dose study in beagle dogs of the CIGB-500 formulation found only transient, non-adverse signs — hypersalivation, hypoactivity, reduced heart rate — with a NOAEL of 2000 µg/kg/day ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}. That is genuinely useful preclinical data. It is also 28 days, in dogs, intravenous, and does not establish human safety.

Interactions. No formal human drug-interaction study exists. Mechanistic cautions only: GHRH analogues (sermorelin, CJC-1295, tesamorelin) synergize strongly with GHRP-6 on GH release — that synergy is the entire basis of the diagnostic combination test ^{6Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →}, and it is also the most common community stacking pattern, meaning the combined endocrine effect is larger than either compound alone; glucose-lowering agents, given the demonstrated insulin/glucose effect ^{11Reference 11Muller AF et al. · 2001RCTBlockade of the growth hormone (GH) receptor unmasks rapid GH-releasing peptide-6-mediated tissue-specific insulin resistance — human (double-blind, placebo-controlled, n=10)View study →}; and corticosteroids or dopaminergic agents, given the cortisol and prolactin effects. All inferred, none tested.

Who should avoid it. Anyone with active or prior malignancy, given GH/IGF-1’s proliferative signaling; anyone with diabetes or impaired glucose tolerance; anyone with adrenal or pituitary disease, or on corticosteroid therapy, given the ACTH/cortisol effect; anyone with a prolactin-sensitive condition; anyone pregnant, breastfeeding or trying to conceive; children and adolescents, in whom an unstudied compound acting on the growth axis during growth is indefensible; competitive athletes; and anyone unwilling to accept an unapproved product of unverified identity and purity.

Injection-specific risks. Reconstituted, self-injected product from unregulated sources brings injection-site reactions, infection from non-sterile technique, endotoxin exposure and dosing error from self-mixed concentrations. These are hazards of how the compound is obtained and used, independent of its pharmacology.

Scope disclosure (honesty, not a claim):

• Human data? Yes, but narrow and old — acute GH-release pharmacology and diagnostic-accuracy studies, essentially all from 1993–2010 in small volunteer or patient groups. There is no human outcome trial for any indication, and no human data at all for the muscle, fat-loss, recovery or anti-aging uses it is sold for.
• Interactions assessed? No. Only mechanism-based cautions (GHRH analogues, glucose-lowering agents, corticosteroids, dopaminergics).
• Pregnancy/lactation assessed? No — no human or animal reproductive data located.
• Long-term safety established? No. No human study has run beyond acute dosing. The longest controlled safety data of any kind is a 28-day intravenous study in dogs ^{24Reference 24Castro J et al. · 2025Subchronic safety assessment of CIGB-500 in beagle dog after repeated daily dose administration over 28 days — animal (dog, regulatory toxicology)View study →}.
• Appetite effect in humans measured? No. It is a consistent user report and a mechanistically-expected class property; no human trial has measured food intake or appetite on GHRP-6.

Never imply safety from silence. Where GHRP-6 has not been studied — chronic dosing, the subcutaneous community route, interactions, pregnancy, cortisol exposure over time, gray-market purity — the correct statement is “not assessed,” not “safe.”

Pregnancy & Lactation

? Not established in pregnancy? Not established in lactation

Not assessed / not established. There are no human pregnancy or lactation data for GHRP-6 and no reproductive-toxicity data located, and there is no regulatory label to draw on. Treat as contraindicated by default in pregnancy and breastfeeding.

Dosage

There is no established human therapeutic dose for GHRP-6, and none is recommended here. It has never been approved for any indication in any country, so there is no label, no titration schedule and no maintenance regimen to report. Everything below is data reported for context, not a personal recommendation.

The only well-characterized human dose is diagnostic: 1 µg/kg intravenously, typically given simultaneously with GHRH 1 µg/kg as a single bolus, with GH sampled over the following 120 minutes ^{6,7,8Reference 6Popovic V et al. · 2000GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250)View study →Reference 7Petersenn S et al. · 2002Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test — human (diagnostic comparison)View study →Reference 8Cordido F et al. · 2003Clinical trialComparison between insulin tolerance test, GHRH, GHRH plus acipimox and GHRH plus GHRP-6 for the diagnosis of adult GH deficiency in normal subjects, obese and hypopituitary patients — human (clinical trial)View study →}. That is a one-off provocative dose administered in a clinic to measure pituitary reserve — it is not a treatment dose and was never intended to be repeated. The pediatric oral study used 300 µg/kg by mouth as a single dose ^{5Reference 5Bellone J et al. · 1995Clinical trialGrowth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric)View study →}, the several-hundred-fold difference reflecting how poorly the peptide is absorbed from the gut. Gray-market practice — microgram-scale subcutaneous injections repeated one to three times daily, frequently stacked with a GHRH analogue — derives from vendor copy and forum convention, not from any human dose-finding study, and neither the chronic schedule nor the subcutaneous route has published human pharmacokinetics. Tachyphylaxis makes the repeated-dosing question a real one that nobody has answered. This entry is informational only.

References

1. Lei T, Buchfelder M, Fahlbusch R, Adams EF. (1995). Growth hormone releasing peptide (GHRP-6) stimulates phosphatidylinositol (PI) turnover in human pituitary somatotroph cells — in vitro (human pituitary tumour cells). Journal of Molecular Endocrinology. https://pubmed.ncbi.nlm.nih.gov/7772238/
2. Ghigo E, Arvat E, Muccioli G, Camanni F. (1997). Growth hormone-releasing peptides — review. European Journal of Endocrinology. https://pubmed.ncbi.nlm.nih.gov/9186261/
3. Bowers CY. (1993). GH releasing peptides — structure and kinetics — human (GH response after IV, SC and oral dosing). Journal of Pediatric Endocrinology. https://pubmed.ncbi.nlm.nih.gov/8374685/
4. Adams EF, Lei T, Buchfelder M, Bowers CY, Fahlbusch R (1996). Protein kinase C-dependent growth hormone releasing peptides stimulate cyclic adenosine 3’,5’-monophosphate production by human pituitary somatotropinomas — in vitro (human pituitary tumour cells). Molecular Endocrinology. https://pubmed.ncbi.nlm.nih.gov/8721987/
5. Bellone J, Ghizzoni L, Aimaretti G, et al. (1995). Growth hormone-releasing effect of oral growth hormone-releasing peptide 6 (GHRP-6) administration in children with short stature — human (controlled clinical trial, paediatric). European Journal of Endocrinology. https://pubmed.ncbi.nlm.nih.gov/7581965/
6. Popovic V, Leal A, Micic D, et al. (2000). GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults — human (multicentre diagnostic-accuracy study, n=250). The Lancet. https://pubmed.ncbi.nlm.nih.gov/11030292/
7. Petersenn S, Jung R, Beil FU. (2002). Diagnosis of growth hormone deficiency in adults by testing with GHRP-6 alone or in combination with GHRH: comparison with the insulin tolerance test — human (diagnostic comparison). European Journal of Endocrinology. https://pubmed.ncbi.nlm.nih.gov/11980622/
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