Hexarelin
Growth-hormone-releasing peptide · ghrelin-receptor (GHS-R1a) agonist
Hexarelin (examorelin) is a synthetic hexapeptide growth-hormone secretagogue and an agonist at the ghrelin receptor GHS-R1a. It is among the most potent of the growth-hormone-releasing peptides in humans — comparable to GHRP-2 in the primary head-to-head data rather than singularly the strongest, despite common claims to that effect. It reached Phase II clinical development for growth-hormone deficiency and for heart failure but was discontinued, and it is approved and marketed nowhere. Three honesty points define it: like other GHRPs it is not growth-hormone-selective and raises ACTH and cortisol; it shows a real but partial and reversible desensitization of the growth-hormone response on continuous dosing, which is the actual basis for the 'cycling' rationale; and it has a genuine but strictly preclinical cardiovascular research literature involving the CD36 receptor that does not support any human cardiac claim. It is prohibited in sport at all times.
The short version
Hexarelin is a small lab-made peptide (six amino acids) that tells the pituitary gland to release growth hormone — through the ghrelin receptor, the same doorway used by GHRP-6 and GHRP-2, and a different one than the body's own growth-hormone-releasing hormone.
It is a strong growth-hormone releaser — about on par with GHRP-2 in head-to-head human tests — but it was never approved as a medicine anywhere; its drug development for growth-hormone deficiency and heart failure was stopped.
Two honest points matter. With repeated daily dosing, the growth-hormone response to hexarelin gradually fades — though it recovers after a break, which is the real reason people 'cycle' it. And like the other peptides in this family, it also raises stress-related hormones such as cortisol. There is interesting heart-related research on hexarelin, but it is all in animals and lab models, not approved human treatment. It is banned in competitive sport.
Molecular identity
Specs
- Molecular weight
- 887.0 g/mol (free base)
- Molecular formula
- C47H58N12O6
- Monoisotopic mass
- 886.46 Da (free base)
- CAS / UNII
- 140703-51-1 · 09QF37C617
- Sequence (6 AA)
- His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH₂PubChem CID 6918297
- Structure / class
- Synthetic GHRP-class hexapeptide (GHS-R1a agonist)PMID 8126144
- Molecular target
- GHS-R1a (ghrelin receptor); CD36 in cardiac tissue (preclinical)PMID 8126144
- Half-life
- ~76 min (rat IV); no clean human value establishedRat IV PKHalf-life curve →
- Regulatory status
- Investigational, approved nowhere · WADA S2.2.4 prohibitedResearch literature / WADA
Plain English
Mechanism
Hexarelin is an agonist (a molecule that switches a receptor on) at the growth-hormone-secretagogue receptor GHS-R1a — the ghrelin receptor, the same docking site the body's own hunger hormone ghrelin uses. Because it acts on this receptor rather than the GHRH receptor (the separate doorway used by growth-hormone-releasing hormone), its growth-hormone-releasing mechanism is distinct from that of GHRH analogs (lab-made copies of that hormone) such as sermorelin or CJC-1295, and combining the two classes produces growth-hormone release exceeding a maximal dose of GHRH alone.
It is a potent releaser. In the primary human head-to-head (a study comparing the two directly), hexarelin and GHRP-2 produced a similar growth-hormone response at equal doses — so hexarelin is best described as among the most potent GHRPs (growth-hormone-releasing peptides) and comparable to GHRP-2, not as singularly the strongest. It is not growth-hormone-selective: alongside growth hormone it raises ACTH and cortisol (two stress-related hormones) to a degree comparable to CRH (the brain signal that normally triggers that stress-hormone release), while its prolactin response (the milk-related hormone) is low. This off-target hormonal signature (effects beyond the intended target) is a property of the GHRP class.
Separately from its pituitary action (its effect on the pituitary, the gland that releases growth hormone), hexarelin has a distinct cardiovascular research literature. In rodent and isolated-heart models (whole hearts studied outside the body) it produces growth-hormone-independent cardioprotective effects (heart-protecting effects that don't depend on growth hormone), and these are mediated not by the ghrelin receptor but by CD36 — a scavenger receptor (a cell-surface protein that binds and clears certain molecules) in the heart whose hexarelin-binding domain (the exact spot hexarelin latches onto) has been mapped by cross-linking studies. This is a genuine line of basic research; it is entirely preclinical (animal- and lab-based, not in people) and does not establish any cardiac benefit or indication in humans.
Sources:PMID 8126144PMID 9285939PMID 10465272PMID 11988484PMID 15176951
Why people reach for it
Potential benefits
Hexarelin is one of the most potent GH-releasing peptides — here's what draws people to it.
- A powerful growth-hormone trigger — Its headline appeal: in human head-to-head testing it released more GH than a maximal dose of GHRH, on par with GHRP-2 — among the strongest GH responses in the GHRP family.
- Raise your own GH, not inject it — It fires the body's own GH pulse through the ghrelin receptor, so the natural feedback and rhythm stay in the loop rather than being overridden by outside hormone.
- Synergizes with a GHRH analog — Because it works the ghrelin receptor, it stacks with a GHRH peptide for a combined pulse bigger than either alone — most commonly CJC-1295 or Sermorelin.
- Body-composition and recovery support — The GH/IGF-1 rise is what people reach for it for — body-composition and training-recovery goals, where IGF-1 drives protein synthesis.
- An intriguing (preclinical) cardiovascular research angle — It has a genuine line of heart research through the CD36 receptor, separate from its GH effect — though this is strictly animal and lab work, not an approved or proven human cardiac benefit.
Sources:PMID 9285939PMID 8126144PMID 10990150
What people reach for Hexarelin for, drawn from what the research reports and how it's used — not proven outcomes or medical claims. Note it also raises ACTH and cortisol as a class effect, and the GH response fades with continuous use.
Implied timing
Best time to dose
Implied best time
Bedtime (empty stomach)
Most people inject Hexarelin at bedtime on an empty stomach, keeping any extra doses fasted and well separated.
- Hexarelin amplifies the body's own GH release, and the single largest natural GH pulse fires in early slow-wave (deep) sleep — a bedtime dose stacks the peptide's pulse on top of that nocturnal surge.
- Food is the reason for the empty stomach: a meal raises insulin and somatostatin (GH's off-switch), both of which blunt the pulse — even a small carb or fat load can cut the response roughly in half, so the dose goes ~2 hours clear of eating.
- Hexarelin desensitizes faster than the other GHRPs, so pulses are kept fasted and time-separated rather than frequent; a fasted pre-workout dose is the usual second injection, but the bedtime dose is the anchor.
- A consistent nightly time matters more than the exact hour; bedtime is the practical anchor, with frequency and cycle length kept conservative to preserve the response.
No study establishes an ideal time of day for Hexarelin — this is reasoned from its GH-secretagogue mechanism and how it's used. As a rule of thumb peptide dosing lands in the midday-to-evening window; for Hexarelin the lean is bedtime, fasted.
Sources:PMID 8126144
How to run it
Dosing & protocol
Hexarelin is injected subcutaneously — the form the calculator is built for. The defining feature of this peptide is desensitization: the GH response fades progressively with continuous use and recovers fully after a break. Every practical decision (frequency, cycle length, washout) flows from that. The ranges below are community and practitioner convention extrapolated from the cited human research; no controlled trial establishes a chronic wellness dose.
Investigational, never approved: hexarelin has human GH-provocation data but no chronic wellness trial. SC wellness doses and cycle lengths are community convention, not trial-proven recommendations. WADA S2.2.4 — prohibited in sport at all times.
Tiered dose ranges
Hexarelin is used at conservative doses precisely because higher or more-frequent dosing accelerates desensitization without proportionate benefit.
- Standard:
- 100 mcg once daily — the most common starting point; preserves receptor sensitivity longest.
- Split daily:
- 100 mcg twice daily (morning + pre-sleep) — typical for an active cycle block; the rahim-1998 desensitization study used a twice-daily SC protocol, so this is the frequency with the best-characterized tolerance curve.
- Why not higher?:
- The GHRP dose-response plateaus (GH release saturates) well before 200+ mcg; pushing higher mainly increases cortisol co-release and accelerates receptor downregulation — nothing is gained.
Subcutaneous administration
Inject on an empty stomach — this is the single most important timing rule for the GH secretagogue class.
- Food window:
- Allow at least 2 hours since the last meal (longer is better). Insulin and somatostatin released after eating directly blunt the GH pulse; even a small carbohydrate or fat load can reduce the response by half. Bedtime (fasted overnight) or fasted pre-workout are the two windows that work.
- Injection site:
- Abdomen (2 inches clear of the navel), love-handle area, or outer thigh. Rotate sites between doses to prevent lipohypertrophy (fatty lumps from repeated injection in one spot).
- Measuring the dose:
- Drawn on a U-100 insulin syringe. At the default mix (5 mg vial + 2 mL BAC water = 2,500 mcg/mL): 100 mcg = 4 IU. The on-page calculator adjusts this live for any vial size.
- Time of day:
- Bedtime is preferred for the main dose — deep slow-wave sleep is where the body's own largest GH pulse occurs, and hexarelin amplifies that pulse. Pre-workout (fasted) is the alternative for a second dose on the split-daily protocol.
Cycle & washout
Cycling is not optional with hexarelin — it is the pharmacology. The rahim-1998 study (n=12 healthy elderly, 16 weeks twice-daily SC) documented a ~45% fall in GH-AUC from baseline to week 16, with full recovery to baseline after a 4-week washout.
- Recommended cycle length:
- 4–8 weeks on. Shorter cycles (4 weeks) experience less accumulated desensitization than longer ones. The 16-week study is the outer boundary of the documented range, not a target.
- Washout:
- 4 weeks minimum off — this is the interval that restored full GH response in the primary data. Do not abbreviate it; a short washout means starting the next block from a still-attenuated baseline.
- Honesty on the desensitization:
- The attenuation is partial and reversible, not complete receptor shutdown. A meaningful GH response remained at week 16 — the marketing framing of rapid or severe tolerance overstates a real but moderate, recoverable effect.
- Frequency discipline:
- Twice-daily is the ceiling, not the floor. If the goal is a longer block, once-daily reduces the rate of attenuation. There is no benefit to pushing to three times daily — more frequent dosing accelerates the fade without compounding GH output.
Reconstitution at a glance
The on-page calculator does this live; the quick reference for the default 5 mg vial:
- Mixing:
- 5 mg vial + 2 mL bacteriostatic water = 2,500 mcg per mL. On a 100-unit (1 mL) insulin syringe: 100 mcg = 4 IU · 150 mcg = 6 IU · 200 mcg = 8 IU.
Substrate the signal needs
Nutritional cofactor precision
Hexarelin works through the ghrelin receptor to amplify the pituitary's GH pulse. Three things determine how productive that pulse is: whether somatostatin (the brake on GH release) is low at dose time, whether the resulting GH/IGF-1 signal has what it needs to drive downstream effects, and whether the cortisol co-release is offset so it doesn't blunt those effects. Every card below maps to one of those three jobs.
Reasoned from GH/IGF-1 physiology and hexarelin's GHRP-class mechanism — not a hexarelin nutrition study. Supplement doses are common practical ranges, not hexarelin-specific findings.
Amplify the pulse — relieve the somatostatin brake
Somatostatin is the hypothalamic hormone that silences GH release; lower it at dose time and the GH pulse is larger.
- L-Arginine:
- 3–6 g taken 30 min before the hexarelin dose. Arginine suppresses somatostatin tone, directly enlarging the GH spike; this is the most reproducible nutritional GH amplifier and acts on the same axis hexarelin stimulates. Take it in the same fasted window.
- Alpha-GPC (α-glycerylphosphorylcholine):
- 300–600 mg, 30–60 min before dosing. Alpha-GPC is a cholinergic (acetylcholine-precursor) compound; cholinergic tone suppresses somatostatin, and the combination with a GHRP has additive GH-release evidence. Also supports cognitive function during the cycle.
Mitigate the cost — offset GH-class glucose and cortisol drift
The GHRP class raises cortisol and can transiently blunt insulin sensitivity; targeted mitigation keeps the metabolic environment clean.
- Berberine:
- 500 mg with the largest meal of the day. GH/IGF-1 elevation and cortisol co-release both tilt glucose metabolism; berberine activates AMPK to offset that drift, keeping fasting glucose and insulin sensitivity stable during the cycle.
- Alpha-lipoic acid (ALA):
- 600 mg with meals. Insulin-sensitizing and antioxidant; pairs with berberine for glucose management and reduces oxidative cost of the cortisol signal. Take with food, not fasted (GI sensitivity on an empty stomach).
- Phosphatidylserine:
- 400–800 mg before bed. Phosphatidylserine blunts the cortisol response to physical and psychological stress; on a twice-daily hexarelin cycle the cumulative cortisol nudge is worth offsetting, especially if training hard.
Supply the substrate — fuel the GH/IGF-1 signal
GH works through IGF-1 to drive protein synthesis; if the raw material isn't there, the pulse produces nothing downstream.
- Protein 1.6–2.0 g/kg/day:
- The GH/IGF-1 axis drives anabolism, but protein is the building block. Target 1.6–2.0 g per kg of body weight daily (about 0.7–0.9 g/lb); leucine-rich sources (whey, eggs, meat) most efficiently trigger the mTOR arm that IGF-1 activates.
- ZMA (zinc + magnesium + B6) before bed:
- Zinc is required for IGF-1 synthesis (low zinc reliably tracks low IGF-1); magnesium supports deep slow-wave sleep — the time slot where the body's own largest GH pulse occurs, and where hexarelin's bedtime dose lands. Take 30–45 min before sleep, away from calcium.
- Vitamin D 2,000–5,000 IU/day:
- Vitamin D receptors are present throughout the GH/IGF-1 axis; deficiency is associated with blunted GH secretion. Maintain a sufficient blood level across the cycle.
Sources:PMID 9285939PMID 10990150
Combinations + timing
Stacking notes + timing windows
Hexarelin acts on the ghrelin receptor (GHS-R1a). The single most evidence-backed combination is pairing it with a GHRH-receptor agonist — they work through independent receptors on the pituitary, so co-administration amplifies GH release beyond what either class can achieve at maximum dose alone. Stacking two GHRPs together (e.g. hexarelin + ipamorelin) hits the same receptor twice — redundant, not synergistic.
Cross-class GH synergy is established in human pharmacology (Arvat 1997 / Ghigo 1994); specific branded pairings are practitioner convention, not head-to-head trials. Hexarelin itself is investigational and never approved — any stack is doubly unproven.
Hexarelin + CJC-1295
The primary stack — ghrelin-arm (hexarelin) + GHRH-arm (CJC-1295) = documented supra-maximal GH synergy.
- Why it works:
- CJC-1295 is a long-acting GHRH analog that activates the GHRH receptor; hexarelin activates the ghrelin receptor. Because these are distinct receptor pathways on the pituitary somatotroph (the GH-releasing cell), the two signals amplify each other — the combination produces more GH than a maximal dose of GHRH alone. This cross-class synergy is the reason the stack exists.
- The protocol:
- Hexarelin 100 mcg + CJC-1295 (with DAC) 2 mg once weekly, or CJC-1295 (without DAC / Mod GRF 1-29) 100 mcg at each hexarelin dose. Both subcutaneous, same fasted window. Because CJC-1295-with-DAC has a multi-day duration, it is typically run on a once-weekly or twice-weekly schedule alongside the hexarelin daily dosing.
- Outcome:
- Amplified GH pulse with longer effective duration (from CJC-1295's extended half-life). The combination used for body-composition, recovery, and GH-axis support goals.
Hexarelin + Sermorelin
A shorter-acting GHRH-arm alternative — preferred when a more physiological, pulsatile pattern is the goal.
- Why it works:
- Sermorelin is the native GHRH(1-29) sequence; its short half-life (~10–20 min) means it produces a sharper, more physiological GH pulse rather than the sustained elevation from CJC-1295-DAC. Paired with hexarelin at the same dose time, the two classes still produce synergistic GH release through independent receptors.
- The protocol:
- Hexarelin 100 mcg + Sermorelin 200–300 mcg, co-injected subcutaneously once or twice daily in a fasted window (bedtime preferred). Because both are short-acting, they are taken together at dose time rather than offset.
- Outcome:
- A more pulse-matched GH release compared to CJC-1295-DAC; preferred by users who want a closer mimic of natural GH secretion or who are sensitive to the prolonged GH elevation of longer-acting GHRH analogs.
Why not hexarelin + another GHRP?
Pairing hexarelin with Ipamorelin, GHRP-2, or GHRP-6 is redundant — same receptor, same lever.
- The redundancy problem:
- Ipamorelin, GHRP-2, and GHRP-6 all act on GHS-R1a — the same ghrelin receptor as hexarelin. Adding a second GHS-R1a agonist saturates the same binding site without opening a new GH-release pathway; you get competition for the receptor, not synergy.
- What to do instead:
- If a lower-desensitization GHRP is wanted for a longer run, switch the anchor peptide to Ipamorelin (which shows less receptor downregulation) and pair that with a GHRH analog. Running hexarelin and ipamorelin simultaneously offers no mechanism-based advantage over either alone with a GHRH partner.
Sources:PMID 9285939PMID 8126144
Reconstitution math
Reconstitution calculator
Reconstitution calculator
Calculated for a 1 mL U-100 insulin syringe (100 units/mL).
Units per dose
4
Draw to this mark on a U-100 syringe
- Volume per dose
- 0.04 mL
- Doses per vial
- 50
- Concentration
- 2.5 mg/mL
One vial lasts
- Daily
- 50 days
- Every other day
- 100 days
- 5×/week
- 70 days
Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.
From the studies
Side effects from research
The characteristic off-target signal (an effect beyond the intended target) is hormonal. Hexarelin is not growth-hormone-selective: in human study it raised ACTH and cortisol (two stress-related hormones) to a degree comparable to CRH (the brain signal that normally triggers them), with a low prolactin response (the milk-related hormone). This co-release (releasing other hormones at the same time) is a property of the GHRP class rather than an impurity effect (a contaminant in the product).
With continuous dosing the growth-hormone response itself attenuates (weakens) — partially and reversibly — as described under tolerance. Hexarelin is approved nowhere and has no modern chronic-use (long-term) clinical safety dataset for wellness or anti-aging purposes; claims of long-term benefit are not supported by a published chronic efficacy trial (a study testing whether it works over time), and the cardiovascular research is preclinical (animal- and lab-based) and does not constitute a human safety or benefit claim.
Sources:PMID 9285939PMID 10990150
As reported in literature
Research dosing ranges
These are the doses actually used in the published studies — the evidence the practical figures above lean on, shown separately so research data is never mistaken for a settled human dose. Hexarelin's human data is research-grade: acute growth-hormone-provocation studies (single doses given to measure the hormone spike) in healthy adults across multiple routes, plus one multi-week subcutaneous study designed to test for desensitization (the fading of the response with repeated dosing). The cardiovascular findings are preclinical (animal and isolated-heart — not human). Doses are reported per kilogram of body weight (1 kg ≈ 2.2 lb). These are not endorsed protocols.
| Dose | Route | Model | Outcome | Sources: |
|---|---|---|---|---|
| 1–2 µg/kg | IV bolus | Human (young adults) | Strong dose-dependent GH rise (peak ~15–30 min); exceeds GHRH; similar to GHRP-2 | PMID 9285939 |
| Multi-route (IV / SC / intranasal / oral) | Various | Human (healthy men) | GH release by all routes; bioavailability SC ~77%, intranasal ~5%, oral <1% vs IV | PMID 8126144 |
| Twice daily | SC | Human (12 healthy elderly, 16 weeks) | GH response declined ~45% over 16 wk; partial and fully reversible after 4-wk washout | PMID 10990150 |
| IV / infusion | IV | Rat / isolated heart | GH-independent cardioprotection via CD36 (preclinical research only) | PMID 10465272 |
Cycling rationale
Receptor dynamics + tolerance
Desensitization (the body's response weakening with repeated dosing) of the growth-hormone response is the most-cited reason for 'cycling' hexarelin, and unlike many such claims it has direct primary-source support — with an important nuance. In the definitive human study, twice-daily subcutaneous (injected into the fat under the skin) hexarelin given to twelve healthy elderly subjects over sixteen weeks produced a progressive fall in the growth-hormone response: the area-under-the-curve (a measure of the total hormone released over time) dropped from about 19.1 µg/L·h at baseline to about 10.5 µg/L·h at week 16 — roughly a 45% attenuation (weakening).
Two qualifiers keep this honest. First, the attenuation was partial — a meaningful growth-hormone response remained at sixteen weeks, not abolition (it was not switched off). Second, it was fully reversible: four weeks after stopping, the response had recovered to baseline (its starting level). The authors' own conclusion was that attenuation after long-term hexarelin is 'partial and reversible.' The data come from a single small cohort (group of subjects), so the marketing framing of rapid or severe tolerance overstates a real but moderate, recoverable effect.
Sources:PMID 10990150
Quick answers
Frequently asked
Is hexarelin the most potent GHRP?
It is among the most potent, but the primary head-to-head data show it is comparable to GHRP-2 rather than singularly the strongest. Both released more growth hormone than a maximal dose of GHRH in human study. The flat 'most potent GHRP' claim overstates what the literature settles.
Does hexarelin stop working over time?
Its growth-hormone effect does attenuate with continuous dosing — about a 45% decline over 16 weeks of twice-daily use in the definitive human study — but the attenuation was partial and fully reversible after a four-week break. That recoverable desensitization is the real pharmacology behind 'cycling,' though the marketing tends to overstate how fast or severe it is.
Is hexarelin good for the heart?
There is genuine research showing hexarelin produces growth-hormone-independent cardioprotective effects through the CD36 receptor — but it is entirely in rodents and isolated-heart models. There is no approved human cardiac indication and no human efficacy trial, so it should be read as a research interest, not a cardiac benefit.
Is hexarelin an approved drug?
No. Hexarelin (examorelin) is investigational only; it reached Phase II development for growth-hormone deficiency and heart failure but was discontinued, and it is approved and marketed nowhere, including by the FDA.
How does hexarelin differ from sermorelin or CJC-1295?
Sermorelin and CJC-1295 are GHRH-receptor agonists; hexarelin acts on a different receptor — the ghrelin receptor (GHS-R1a). Because they work through independent pathways, combining a GHRP with a GHRH analog produces synergistic growth-hormone release.
Is hexarelin banned in sport?
Yes. Growth-hormone-releasing peptides including examorelin (hexarelin) are named on the WADA Prohibited List under Section S2.2.4 and are prohibited at all times, in and out of competition.
Primary sources
References
- PubChem CID 6918297PubChem — Hexarelin free base (CID 6918297)
- PMID 8126144Ghigo et al. 1994 — hexarelin GH release and multi-route bioavailability in humans (J Clin Endocrinol Metab)
- PMID 9285939Arvat et al. 1997 — hexarelin & GHRP-2 GH potency and ACTH/cortisol/prolactin co-release (Peptides)
- PMID 10990150Rahim & Shalet 1998 — partial, reversible desensitization to 16-wk hexarelin (Growth Horm IGF Res)
- PMID 10465272Locatelli et al. 1999 — GH-independent cardioprotection by hexarelin in rat (Endocrinology)
- PMID 11988484Bodart et al. 2002 — CD36 mediates the cardiovascular action of GHRPs/hexarelin (Circ Res)
- PMID 15176951Demers et al. 2004 — mapping of the hexarelin/GHRP binding site on CD36 (Biochem J)
- PMID 25278975Mao et al. 2014 — review: hexarelin, CD36 and GH-independent cardioprotection (J Geriatr Cardiol)
- WADA Prohibited List S2.2.4WADA Prohibited List — S2.2.4 GH-Releasing Peptides (examorelin/hexarelin named)
Research use only · Not medical advice · Updated 2026-06-01