Educational reference only

Hexarelin is a prescription medication in most countries. This page is for educational reference only. Underground Biohacking does not provide dosing protocols, interaction warnings, or usage guidance for prescription compounds. If you are using or considering Hexarelin, work with a licensed clinician.

Growth hormone

Hexarelin

Name: Hexarelin
Creator: Chris Hallewell

By Chris Hallewell, Founder, Underground Biohacking

Last reviewed 6 August 2026

Research only / restricted

Hexarelin is a synthetic six amino acid peptide that makes the pituitary release growth hormone. Real human trials ran in the 1990s, including studies of heart function. That makes the evidence stronger than for most research peptides. Those same trials found a clear problem: the growth hormone response fades when you keep using it. Hexarelin is not an approved medicine anywhere. No trial has followed anyone taking it beyond about ten months.

What is Hexarelin?

Hexarelin is a growth hormone releasing peptide, usually shortened to GHRP. It is built from six amino acids joined in a short chain, which makes it a hexapeptide. That six is where the name comes from. It was made in a laboratory as a version of an earlier peptide called GHRP-6, and it also appears under the name examorelin. It works by switching on the growth hormone secretagogue receptor. That is the same lock your own hunger hormone, ghrelin, uses. Ghrelin was only identified years after hexarelin was built, so the synthetic key came before anyone found the natural one. The structure matters in two ways. The published sequence contains mirror image and chemically modified amino acids that do not appear in ordinary human proteins. Those changes slow it down being broken apart, so enough of it survives to reach the pituitary. The structure also seems to let it act on the heart directly. In human trials it changed heart performance when injected growth hormone did not. That points to a target in heart tissue, not a knock on effect of the hormone.

What is Hexarelin prescribed for?

In healthy men, one injection of hexarelin briefly increased the force of the heart's contraction.^[1]Human study
In adults whose pituitary had failed, hexarelin raised the share of blood the left ventricle pushed out with each beat.^[2]Human study
In men with coronary artery disease undergoing bypass surgery, hexarelin improved heart performance during the operation.^[3]Human study
In patients whose heart failure came from blocked arteries, hexarelin lifted pumping fraction, but it did nothing in patients with dilated cardiomyopathy.^[4]Human study
In short prepubertal children treated for six to ten months, growth speed rose.^[5]Human study
In healthy elderly people, a short course of hexarelin nudged up IGF-1, the hormone that does most of growth hormone's downstream work.^[6]Human study
In rats recovering from a heart attack, hexarelin improved heart function about as much as growth hormone itself did.^[7]Animal or lab study only

How does Hexarelin work?

Hexarelin knocks on a different door. It is a short synthetic peptide that acts on the ghrelin receptor, also called the growth hormone secretagogue receptor. Ghrelin, a stomach hormone, is the natural key for that lock. Hexarelin is not a GHRH copy, so it does not use the GHRH receptor. Switching the ghrelin receptor on raises calcium inside pituitary cells, and those cells then release growth hormone. The response fades with continued use. In lab cells the calcium signal drops within minutes, and in people a long course blunted the growth hormone rise. That blunting reversed after treatment stopped.

Educational reference only. Talk to a licensed clinician for any decisions on Hexarelin.

What are the side effects of Hexarelin?

Effect	How serious	What to watch
The growth hormone response shrinks with continued use. In healthy elderly adults, the response fell over sixteen weeks of treatment and recovered after the study ended.^[8]	Expected, partial, and reversible	A shrinking effect over weeks is the normal pattern here, not a rare reaction
The same fade showed up fast in children. The growth hormone peak dropped within a week and then sat at that lower level for months.^[5]	Expected within days	Growth hormone peak, if it is being measured at all
Hexarelin is not clean. After a dose it also stimulates the cells that make prolactin and the cells that drive the stress hormone axis.^[9]	Mild in short trials, unstudied over years	Prolactin and cortisol, if it is used repeatedly
Appetite rose in healthy male volunteers soon after it was given. That fits its action on the ghrelin receptor.^[10]	Mild and short lived	Hunger and weight
No trial has followed anyone on hexarelin for longer than about ten months. Nothing is on record about safety beyond that point.	Unknown	None

Is Hexarelin legal in 2026?

Checked 6 August 2026. Hexarelin is not approved by the FDA for any use, and it was never licensed as a medicine. On the FDA list of bulk drug substances that may present significant safety risks, hexarelin is not named. Several close relatives are, including GHRP-2, GHRP-6 and ipamorelin acetate. That page was current as of 22 April 2026. FDA stated on the record on 23 July 2026 that none of these substances could ever have been lawfully compounded under section 503A. That has been true since 1997. None of them were ever in Category 1. A PCAC vote is advisory and not binding. Nothing about that position has changed.

Status checked 6 August 2026 against the primary source.

Educational reference only. Talk to a licensed clinician for any decisions on Hexarelin.

If you are considering Hexarelin

This page does not provide dosing, cycling, stacking, or sourcing guidance for Hexarelin. The protocol conversation belongs with a licensed clinician who can review your bloodwork, history, and goals.

Where to buy Hexarelin

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Frequently Asked Questions

What does hexarelin actually do?

It tells the pituitary gland to release a pulse of growth hormone. It does that by switching on the growth hormone secretagogue receptor, the same lock your own hunger hormone ghrelin uses. Growth hormone then raises IGF-1, which carries out most of the downstream work. In healthy elderly people, a short course lifted IGF-1 a little. Hexarelin also acts on the heart in a way that does not depend on growth hormone at all.

Is the heart research on hexarelin real?

Yes, and it is unusually solid for a research peptide. Small human trials in the 1990s and early 2000s used radionuclide scans and echocardiography. Hexarelin raised the left ventricle's ejection fraction in healthy men, in adults with pituitary failure, and in coronary artery disease patients during bypass surgery. Injected growth hormone did not do the same. But these were single doses in small groups. No trial tested whether anyone lived longer or felt better.

Does hexarelin stop working if you keep using it?

The growth hormone response does fade. In elderly adults, it had dropped by four weeks and stayed lower at sixteen weeks. When they were retested a month after that study ended, it had returned to where it started. Shorter intermittent courses did not blunt it at all. In short children the drop appeared within a week. Their growth still improved despite the blunted response. So the fade is real and partial, and it reversed once treatment stopped.

How is hexarelin different from ghrelin or ipamorelin?

Ghrelin is the natural hormone your stomach makes. Hexarelin is a synthetic version of that signal. In a head to head human study, ghrelin released more growth hormone than hexarelin did, and raised prolactin and cortisol more. Ipamorelin is another synthetic secretagogue, and it is named on the FDA safety risk list while hexarelin is not. They all act on the same receptor family.

Is hexarelin an approved medicine?

No. It is not approved by the FDA for any use, and it was never licensed as a medicine in any country. It reached human trials in the 1990s, showed real effects, and then development stopped. FDA has stated that substances like this could never have been lawfully compounded under section 503A. Anything sold outside a research setting carries no approval, no quality control and no oversight behind it.

What should you ask a doctor about hexarelin?

Ask what your growth hormone and IGF-1 levels actually are, because low levels have real named causes worth finding. Ask whether the heart problem you are worried about has an approved treatment, since the hexarelin heart data comes from single doses in small trials. Ask about prolactin and cortisol, which hexarelin also moves. And ask what happens once the growth hormone response fades, because in the long trials it always did.

References

1.Bisi G, et al. (1999). Acute cardiovascular and hormonal effects of GH and hexarelin, a synthetic GH-releasing peptide, in humans. Journal of endocrinological investigation. PMID: 10342360. DOI: 10.1007/BF03343555.
2.Bisi G, et al. (1999). Cardiac effects of hexarelin in hypopituitary adults. European journal of pharmacology. PMID: 10528131. DOI: 10.1016/s0014-2999(99)00537-3.
3.Broglio F, et al. (2002). Effects of acute hexarelin administration on cardiac performance in patients with coronary artery disease during by-pass surgery. European journal of pharmacology. PMID: 12144941. DOI: 10.1016/s0014-2999(02)01934-9.
4.Imazio M, et al. (2002). GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction due to dilated and ischemic cardiomyopathy. European journal of heart failure. PMID: 11959048. DOI: 10.1016/s1388-9842(01)00223-9.
5.Klinger B, et al. (1996). Desensitization from long-term intranasal treatment with hexarelin does not interfere with the biological effects of this growth hormone-releasing peptide in short children. European journal of endocrinology. PMID: 8766941. DOI: 10.1530/eje.0.1340716.
6.Ghigo E, et al. (1996). Short-term administration of intranasal or oral Hexarelin, a synthetic hexapeptide, does not desensitize the growth hormone responsiveness in human aging. European journal of endocrinology. PMID: 8921821. DOI: 10.1530/eje.0.1350407.
7.Tivesten A, et al. (2000). The growth hormone secretagogue hexarelin improves cardiac function in rats after experimental myocardial infarction. Endocrinology. PMID: 10614623. DOI: 10.1210/endo.141.1.7249.
8.Rahim A, Shalet SM (1998). Does desensitization to hexarelin occur? Growth hormone & IGF research. PMID: 10990150. DOI: 10.1016/s1096-6374(98)80039-7.
9.Arvat E, et al. (2001). Endocrine activities of ghrelin, a natural growth hormone secretagogue (GHS), in humans: comparison and interactions with hexarelin, a nonnatural peptidyl GHS, and GH-releasing hormone. The Journal of clinical endocrinology and metabolism. PMID: 11238504. DOI: 10.1210/jcem.86.3.7314.
10.Korbonits M, et al. (1999). The growth hormone secretagogue hexarelin stimulates the hypothalamo-pituitary-adrenal axis via arginine vasopressin. The Journal of clinical endocrinology and metabolism. PMID: 10404825. DOI: 10.1210/jcem.84.7.5811.

One more time, because it matters

This page exists to identify Hexarelin and explain what the research describes. Underground Biohacking does not advise on dosage, cycling, stacking, or where to source prescription compounds. If Hexarelin is part of your plan, that conversation belongs with a clinician who can review your labs, history, and goals. Not with a website.