Hexarelin
Examorelin; GHRP-His-D-2-MeTrp-Ala-Trp-D-Phe-Lys-NH2; EP-23905
The Ground Truth Score
four plain questions, never one numberHexarelin is one of the few GHRPs with actual human data, but it builds tolerance fast and raises cortisol alongside GH.
Bottom line
Hexarelin is a synthetic GHRP that demonstrably raises GH in humans across multiple small studies from the 1990s, but rapid tachyphylaxis, cortisol/prolactin co-elevation, and zero long-term safety data keep it well below clinical adoption.
Does the science back it?
Do real people feel it?
Is it safe?
Could it be placebo?
"Do real people feel it?" is anecdote, not proof, weighted up because the science is thin, never because it beats a trial. And "could it be placebo?" is not an insult: if you feel better, that's real to you. The point is only to know whether you're paying peptide prices for an expectation.
Why is the evidence this thin? It's mostly economics →
Dose at a glance
full dosing ↓100-200 mcg SubQ 1-3x daily, fasted; cycling required due to fast tachyphylaxis (community reported, no established clinical protocol)
Reported, not prescribed. Verify your vial and your math.
The gist
- More actual human data than almost any grey-market GHRP, small 1990s studies showing it demonstrably raises GH, but the response halves within a few weeks of daily dosing.
- The GH-independent cardioprotection angle is real in rodents and has two small human signals, but the studies were acute IV challenges with no placebo arm and n=5 in the most-cited one.
- The catch: hexarelin hits cortisol and ACTH alongside GH at every dose, and you have to cycle aggressively just to stay ahead of the receptor burnout.
First documented human use
1994, Ghigo et al., University of Turin. Acute IV/SC dosing in healthy men; GH-releasing activity confirmed in the first controlled human pharmacology paper (European Journal of Clinical Pharmacology, 1994).
The pitch
What people claim it does
Stated plainly and neutrally, exactly as you'll hear it. I grade each one below.
- Potent GH release without the need for GHRH co-administration
- Potential cardioprotective effects independent of GH
- Faster GH pulse than GHRH analogs
- May improve body composition via IGF-1 downstream signaling
- Explored as a diagnostic tool for pituitary GH reserve
The data behind each bullet
What actually backs it
Hexarelin robustly raises GH levels in healthy adults
Multiple small human studies (1994-2001) consistently show significant IV or SC hexarelin raises serum GH above GHRH-alone in healthy volunteers, GH-deficient patients, and acromegalic patients. Effect is dose-dependent and replicated across labs.
Ghigo et al. 1994, European Journal of Clinical Pharmacology ↗GH response desensitizes substantially within weeks of daily dosing
PMID 10990150 directly examined desensitization and found partial but real attenuation. PMID 10341859 (Rahim et al. 1999, 16 weeks, twice-daily SC dosing) specifically examined chronic HPA and prolactin burden: it found NO significant progressive prolactin elevation over 16 weeks and concluded over-stimulation of the pituitary-adrenal axis and prolactin secretion do not occur at the studied dosing regimen. The acute per-injection cortisol/ACTH rise is real and well-documented, but the Rahim chronic study found ACTH/cortisol AUC decreased during the study period, not persisted. Pattern of GH desensitization is consistent across labs.
Does desensitization to hexarelin occur? PubMed 10990150 ↗Hexarelin has acute GH-independent cardioprotective effects in ischemic cardiomyopathy but not dilated cardiomyopathy in humans
Imazio et al. 2002 (EJHF, PMID 11959048) found LVEF improved in ischemic cardiomyopathy patients (n=5, peak LVEF 26.2+/-2.5%, p<0.05) but NOT in dilated cardiomyopathy patients (n=8, LVEF unchanged, p=NS) after acute IV hexarelin. GH rose similarly in both groups. This was an acute IV challenge, not a treatment study, and it lacked a randomized placebo arm. The n=5 for ischemic CM is too small to draw firm conclusions. Moretti et al. 2001 (PMID 11322491) reported small measurable ejection fraction changes in GH-deficient subjects. Sample sizes across all cardiac studies are very small and findings should be considered preliminary.
Imazio et al. 2002, European Journal of Heart Failure, PMID 11959048 ↗Hexarelin raises cortisol and ACTH alongside GH at standard acute doses
PMID 9430449 (Arvat et al., Neuroendocrinology 1997) tested whether hexarelin's ACTH/cortisol-releasing effect operates via CRH or vasopressin. Its title and conclusion are explicitly 'hexarelin shows NO INTERACTION with corticotropin-releasing hormone and vasopressin on ACTH and cortisol secretion in humans.' The study confirms hexarelin does raise ACTH and cortisol acutely, but shows this occurs via a CRH/AVP-independent pathway, not by synergizing with the classical axis mediators. PMID 10341859 (Rahim et al. 1999) established that while the acute per-injection ACTH/cortisol rise is real, chronic twice-daily SC dosing over 16 weeks did NOT produce progressive sustained HPA axis overstimulation. The acute cortisol co-elevation is a class effect of potent GHRPs, strongest with hexarelin, but it does not translate to chronic hypercortisolism at studied doses.
Arvat et al. 1997, Neuroendocrinology, PubMed 9430449 ↗Hexarelin improves cardiac function and reduces fibrosis in rodent myocardial infarction models
Multiple rodent studies (PMID 10614623, PMC5949285, PMC7018219) consistently show improved ejection fraction and reduced fibrosis post-MI. Animal data is internally consistent and mechanistically plausible via GHS-R1a and adenosine A2 receptor pathways. Does not establish human efficacy.
Hexarelin preserves myocardial function in mouse MI model, PMC5949285 ↗Mechanism
How it's assumed to work
Assumed · theoretical pathway
Assumed (largely confirmed in animal/cell models, partially confirmed in humans): Hexarelin binds GHS-R1a (the ghrelin receptor) at both pituitary somatotrophs and hypothalamic GHRH neurons, triggering pulsatile GH release via IP3/DAG signaling. It also binds a second, as-yet-incompletely-characterized receptor in cardiac tissue (possibly CD36 or adenosine A2 receptor) that mediates GH-independent cardioprotective effects. The dual receptor profile is better established mechanistically in rodents than in humans.
Dosing & handling
What users and clinicians report
100-200 mcg subcutaneous injection, 1-3 times per day. Often cycled 5 days on / 2 days off or 8 weeks on / 4 weeks off to slow tachyphylaxis. Some protocols front-load at 200 mcg then drop to 100 mcg. Research doses in human studies ranged from 1-2 mcg/kg IV or SC.
Reported in grey-market user communities, not prescribed. Biggest dosing risk: tachyphylaxis is dose-frequency dependent, so users escalate dose chasing the original response, stacking cortisol burden. No human dose-finding study for chronic SC use exists.
Timing & food
Typically administered fasted or at least 2-3 hours post-meal to avoid blunting GH pulse by insulin. Most users inject pre-sleep or pre-fasted morning workout to align with natural GH pulsatility. Second and third daily doses spaced at minimum 3-4 hours apart.
Half-life
55-70 minutes (subcutaneous). Substantially longer than GHRP-6 due to D-amino acid substitutions that resist proteolytic degradation.
Reconstitution sensitivity
Moderate. Lyophilized powder reconstituted with bacteriostatic water (BAC water). Stable refrigerated for approximately 4 weeks post-reconstitution. Light and heat sensitive; avoid freeze-thaw cycles. Standard GHRP reconstitution rules apply.
Real-world signal
What people actually report
Anecdote, not proof, weighted because the science is thin. Here's the record, graded on volume, consistency, and how credible the sources are.
Volume
Moderate. Hexarelin has a real user community on peptide forums (r/Peptides, evolutionary.org), smaller than ipamorelin but more than obscure compounds. Discussed specifically for GH pulse strength.
Consistency
Low-moderate. GH pulse strength gets consistent reports. Body composition results are inconsistent and highly confounded. Cardiac benefits are rarely the user motivation and not well tracked.
Source credibility
Low. Most reports come from grey-market users stacking multiple compounds with no controls. The few who try hexarelin solo consistently note strong but short-lived GH flushing and fatigue, which aligns with the cortisol co-elevation seen in studies.
- Anecdote: strong warmth and flushing within 10-20 minutes of injection, described as noticeably more intense than ipamorelin at equivalent doses.
- Anecdote: fatigue and hunger spike within 30-60 minutes post-injection, consistent with the cortisol and ghrelin-pathway activation documented in studies.
- Anecdote: GH-related effects (morning pump, sleep quality improvement, finger tingling) reportedly fade within 3-4 weeks of daily use, prompting users to cycle off.
- Anecdote: some users report better acute response when combining with a GHRH analog (CJC-1295), consistent with the synergistic pituitary mechanism, though this muddies attribution entirely.
Placebo risk, Moderate
GH pulse effects (warmth, fatigue, mild transient IGF-1 rise) are somewhat objective, which reduces placebo risk for the acute hormonal response. However, body composition and recovery improvements over weeks are highly subjective and confounded by training, diet, and co-administered compounds, placing longer-term outcome claims in moderate placebo territory.
Risk panel
What could go wrong
Adverse events
Consistent acute cortisol and ACTH elevation at each GH-releasing dose. Acute prolactin rise per injection is documented in short-term studies. Importantly, PMID 10341859 (Rahim et al. 1999, 16 weeks, twice-daily SC dosing) found NO significant progressive prolactin elevation over the study period and concluded that over-stimulation of the pituitary-adrenal axis and prolactin secretion do not occur with chronic dosing at the studied regimen. Water retention and fatigue reported by users. Rapid tachyphylaxis (GH response halves within 2-4 weeks of daily use). No serious adverse events documented in controlled studies, but sample sizes are all under 30 and maximum study duration was 16 weeks.
Theoretical concerns
Sustained prolactin elevation carries gynecomastia risk in men and menstrual irregularity risk in women. Chronic cortisol co-elevation is metabolically counterproductive when the goal is body composition. GHS-R1a is expressed in tumor tissue; unknown whether chronic stimulation promotes proliferation. No carcinogenicity studies in humans.
Contraindications
Active malignancy (GHS-R1a expressed in some cancers). Active acromegaly. Pregnancy and lactation (no data). Prolactin-sensitive conditions (prolactinoma, prolactin-driven breast cancer history). Co-administration with other GHRPs compounds cortisol/prolactin burden.
Honest unknowns
No long-term human safety data exists beyond ~6 months. Oral bioavailability in humans is not established from RCT data. Interaction with GLP-1 receptor agonists (now widely used) has not been studied. Compounding purity and dose accuracy from grey-market sources is unverified.
Confound watch
Hexarelin is almost always stacked with GHRH analogs (CJC-1295, sermorelin) or other GHRPs (ipamorelin), making solo attribution impossible. Many users are also on TRT, which independently improves body composition and recovery. GLP-1 agonists (tirzepatide, semaglutide) now common in the same user cohort and produce dramatic fat loss attributable to the GLP-1 drug, not the peptide. Resistance training and caloric protocols are strong confounders for any body-composition claim.
History
Discovery → first use → status
- 1993Romano Deghenghi and colleagues at Europeptides (Milan) synthesize hexarelin as a potency-optimized GHRP-6 analog. Structure: His-D-2-MeTrp-Ala-Trp-D-Phe-Lys-NH2.
- 1994First human pharmacology published by Ghigo, Arvat, Deghenghi et al. (Turin group) in European Journal of Clinical Pharmacology, confirming robust GH secretion in healthy men.
- 1999-2002Italian research groups publish small human cardiac studies showing GH-independent effects on LVEF in ischemic cardiomyopathy, generating brief interest in hexarelin as a cardioprotective agent.
- 2005-presentNo pharmaceutical sponsor advances hexarelin to Phase 3. Compound remains research-only; ghrelin itself and synthetic ghrelin analogs absorb most cardiovascular research focus. Hexarelin enters grey-market peptide trade as a research chemical.
Verification
The COA standard, applied
Grade adversarially re-reviewed 2026-06-21 and downgraded. Citation characterizations corrected 2026-06-22: (1) PMID 9430449 (Arvat et al.) title/conclusion is explicitly 'shows NO interaction with CRH and vasopressin', hexarelin raises ACTH/cortisol via a CRH/AVP-independent pathway, not by synergizing with the classical axis; claim text updated to reflect this accurately. (2) PMID 10341859 (Rahim et al.) found NO significant progressive prolactin elevation and ACTH/cortisol AUC decreased during chronic dosing, the opposite of what earlier claim text and risk text stated; both corrected. (3) Imazio 2002 cardiac citation notes updated to reflect that the study was an acute IV challenge without a randomized placebo arm, not a controlled treatment study.
The full verification standard →Sources
Where this comes from
- Ghigo et al. 1994, first human pharmacology, European Journal of Clinical Pharmacology ↗· Establishes that hexarelin raises GH in healthy men; foundational human paper by the Turin group.
- Imazio et al. 2002, cardiac study, European Journal of Heart Failure, PMID 11959048 ↗· Human cardiac study with the fewest design controls: acute IV challenge only, not a treatment study, no randomized placebo arm. Small n (n=5 ischemic CM, n=8 dilated CM). LVEF improved in ischemic CM patients (p<0.05) but was unchanged in dilated CM (p=NS). Cited as the primary human cardiac evidence but its acute, uncontrolled design limits conclusions substantially.
- Does desensitization to hexarelin occur? PubMed 10990150 ↗· Directly addresses tachyphylaxis question in humans. Confirms partial reversible attenuation.
- Chronic hexarelin and pituitary-adrenal axis, PubMed 10341859 ↗· Rahim et al. 1999. 16-week twice-daily SC hexarelin (1.5 mcg/kg). Key safety-relevant finding: the study found NO significant progressive prolactin elevation and concluded over-stimulation of the pituitary-adrenal axis and prolactin secretion do NOT occur at this chronic dosing regimen. ACTH/cortisol AUC decreased during the study period. Acute per-injection responses are real, but this chronic study found they do not accumulate into sustained hyperprolactinemia or hypercortisolemia.
The four lenses reflect the evidence and the real-world record as of the last review and will change as data arrives. Real-world signal and reported feedback are anecdote, not proof. Nothing here is medical advice or a prescription.