Hexarelin
Hexarelin
The short answer
Hexarelin is a synthetic hexapeptide growth hormone releasing peptide (GHRP) that stimulates growth hormone release through the ghrelin/GH-secretagogue receptor, a pathway mapped in the acute GH-stimulation work of Ghigo et al., 1994 (JCEM 78(3):693-698).
This page is general educational information, research-use framing only, not medical advice. Any decision about a research compound belongs with a qualified clinician.
What is hexarelin?
Short answer: Hexarelin is a six-amino-acid research peptide that prompts the pituitary to release growth hormone by acting on the GH secretagogue (ghrelin) receptor.
Hexarelin is a six-amino-acid synthetic peptide in the growth hormone releasing peptide (GHRP) family that triggers growth hormone secretion. It was developed as a GH secretagogue and studied for its potent acute GH-releasing action across intravenous, subcutaneous, intranasal, and oral routes in man (Ghigo et al., 1994).
Like other GHRPs, hexarelin acts on the growth hormone secretagogue receptor (the ghrelin receptor) rather than on the growth hormone releasing hormone (GHRH) receptor. That places it in the same functional class as GHRP-2, GHRP-6, and ipamorelin, which are compared later on this page. Hexarelin is a research compound, not an approved therapy, and the human literature is thin compared with the animal data.
How does hexarelin work in the body?
Short answer: Hexarelin binds the GH secretagogue receptor to drive a sharp, short pulse of the body's own growth hormone, and a separate research thread reports it also binds cardiac CD36.
Hexarelin binds the growth hormone secretagogue receptor and drives a brief, potent pulse of growth hormone from the pituitary. This acute release was characterized in humans by Ghigo et al., 1994, who reported strong GH secretion after single doses given by several routes.
The peptide works upstream of the GH axis: it prompts the pituitary to release its own stored growth hormone rather than adding growth hormone directly. Because the effect depends on the secretagogue receptor, hexarelin's action overlaps with the natural hormone ghrelin. A second research thread identified a distinct cardiac receptor for GHRPs, later characterized as CD36 (Bodart et al., 1999), and reported that CD36 mediates the cardiovascular action of these peptides in the heart (Bodart et al., 2002). This CD36 finding is why hexarelin is sometimes discussed separately from other GHRPs, but the cardiac work is exploratory and no completed human outcome trials support a heart benefit.
What does research report about hexarelin dosing?
Short answer: Published hexarelin dosing comes from small, weight-based single injections used to provoke a GH pulse in acute testing, not from long-term protocols, and none of it is a dosing recommendation.
Published hexarelin work used small, weight-based single doses given by injection in acute GH-stimulation testing, not long-term self-administration protocols. The table below summarizes what the research reported, framed as reported ranges only.
| Setting | What research reported | Route | Source |
|---|---|---|---|
| Acute GH-stimulation testing | Single microgram-per-kilogram doses used to provoke a GH pulse | Injection (also intranasal and oral tested) | Ghigo et al., 1994 |
| Repeated / long-term exposure | GH response attenuated over time (tolerance) | Injection | Rahim et al., 1998 |
| Cardiac / CD36 signaling interest | Binding and cardiovascular action characterized in tissue and animal models | Research models | Bodart et al., 1999; Bodart et al., 2002 |
This is not a dosing recommendation. The doses above come from controlled research settings and do not tell any reader what to take. Any personal dose, schedule, or decision about GH-axis compounds belongs with a qualified clinician who can review your full health picture.
What is hexarelin's half-life, and how does it compare?
Short answer: Hexarelin has a short half-life, so its GH pulse is brief, which is typical for the GHRP class.
Hexarelin's short half-life means the GH pulse it produces is brief, a trait it shares with the wider GHRP class. The comparison below sets it against the other secretagogues in this hub.
| Compound | Class | Receptor target | Reported note |
|---|---|---|---|
| Hexarelin | GHRP (hexapeptide) | GH secretagogue receptor + CD36 | Potent acute GH release (Ghigo et al., 1994); GH response attenuates with long-term dosing (Rahim et al., 1998); cardiac CD36 action (Bodart et al., 2002) |
| GHRP-2 | GHRP | GH secretagogue receptor | Same secretagogue-receptor family (see GHRP-2 hub) |
| GHRP-6 | GHRP | GH secretagogue receptor | Same family, strong appetite signal reported (see GHRP-6 hub) |
| Ipamorelin | GHRP | GH secretagogue receptor | Reported as a selective GH releaser (Raun et al., 1998) |
| MK-677 (oral secretagogue) | Non-peptide | GH secretagogue receptor | Raised fasting glucose, lowered insulin sensitivity in older adults (Nass et al., 2008) |
For readers comparing the class more broadly, CJC-1295 acts on the separate GHRH pathway and was reported to sustain GH and IGF-1 (Teichman et al., 2006), which is why GHRH analogs are often discussed alongside GHRPs.
What side effects and cautions does research note?
Short answer: The defining hexarelin caution is tolerance, the GH response fades with long-term dosing, and human safety data is short-term and limited.
The main hexarelin-specific caution in the literature is tolerance: the GH response can fade with repeated or extended dosing, as reported by Rahim et al., 1998. That attenuation is a defining limit of the compound, and human data on it remains sparse.
Across the GH secretagogue class, research has flagged metabolic effects worth knowing. Oral MK-677 raised fasting glucose and reduced insulin sensitivity in older adults (Nass et al., 2008), a reminder that GH-axis stimulation can shift glucose handling. Hexarelin's CD36 binding (Bodart et al., 2002) is an active research question, not a settled safety profile. Because human hexarelin data is limited and short-term, long-term safety is not established, and none of this substitutes for clinician review.
How does hexarelin fit with the other secretagogues?
Short answer: Hexarelin is one of several GHRPs acting on the same GH secretagogue receptor, but it stands out for its reported potency and its added CD36 cardiac binding.
Hexarelin sits inside the GHRP set alongside GHRP-2, GHRP-6, and ipamorelin, all acting on the same GH secretagogue receptor. What sets hexarelin apart in the literature is its reported potency (Ghigo et al., 1994) and the CD36 cardiac finding (Bodart et al., 2002), while ipamorelin is the one reported as more selective for GH release (Raun et al., 1998).
If you are mapping the GH axis as a whole, the practical split is GHRPs (secretagogue-receptor agonists like hexarelin) versus GHRH analogs (like CJC-1295, which sustained GH and IGF-1 in Teichman et al., 2006). The two arms are studied for different reasons, and this hub covers only the GHRP side.
Keep reading
Related research and verification
Hexarelin: FAQ
Sourcing research-grade peptides?
Talk to the Peptara Labs team about purity, third-party certificates of analysis, and cold-chain shipping.
References
- Ghigo E, Arvat E, Gianotti L, et al. Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man. J Clin Endocrinol Metab. 1994;78(3):693-698. (PMID 8126144). Characterized hexarelin's potent acute growth hormone release across multiple routes in healthy volunteers.
- Bodart V, Bouchard JF, McNicoll N, et al. Identification and characterization of a new growth hormone-releasing peptide receptor in the heart. Circ Res. 1999;85(9):796-802. (PMID 10532947). Identified a distinct cardiac binding protein for GHRPs, later characterized as CD36.
- Bodart V, Febbraio M, Demers A, et al. CD36 mediates the cardiovascular action of growth hormone-releasing peptides in the heart. Circ Res. 2002;90(8):844-849. (PMID 11988484). Reported that CD36 mediates the cardiovascular action of GHRPs, an exploratory research signal only.
- Rahim A, O'Neill PA, Shalet SM. Growth hormone status during long-term hexarelin therapy. J Clin Endocrinol Metab. 1998;83(5):1644-1649. doi:10.1210/jcem.83.5.4812 (PMID 9589671). Described attenuation of the growth hormone response with repeated long-term hexarelin exposure.
- Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561. doi:10.1530/eje.0.1390552 (PMID 9849822). Cited for ipamorelin as a selective GH releaser that did not meaningfully raise cortisol or prolactin.
- Nass R, Pezzoli SS, Oliveri MC, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial. Ann Intern Med. 2008;149(9):601-611. (PMID 18981485). Reported that oral MK-677 raised fasting glucose and lowered insulin sensitivity in older adults.
- Teichman SL, Neale A, Lawrence B, et al. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006;91(3):799-805. (PMID 16352683). Cited for the GHRH analog CJC-1295 sustaining GH and IGF-1, contrasting the GHRH arm with the GHRP class.
General educational information only, research-use framing, not medical advice. Confirm the current status where you live and consult a qualified professional before acting.