Hexarelin

A synthetic six-amino-acid peptide, given the official drug name examorelin, that makes the pituitary gland release growth hormone. Its chain is His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2: two of the six building blocks are mirror-image forms, one of those also carries an extra methyl group, and the end of the chain is capped with an amide. None of that can be written in the standard one-letter code, so the sequence field is deliberately left empty rather than filled with a string that would describe a different molecule. PubChem gives C47H58N12O6 and 887.0 g/mol (CID 6918297). Its first human dose-finding study was run and written up by Mediolanum Farmaceutici in Milan in 1994; development stopped later in the 1990s, and it is now sold online as a research chemical.

Sold as

Injected under the skin or into a vein in the published studies. A nasal spray was used in the studies in short children, and an oral form was also tested.

Legal status in the EU

Not approved as a medicine in the EU, the United States or anywhere else; no marketing authorisation has ever been granted and no trial of it is registered on ClinicalTrials.gov. In the United States it cannot legally be made up by a pharmacy either: it does not appear anywhere on the FDA's list of bulk drug substances nominated for compounding under section 503A, updated 14 May 2026, which does list the related peptides GHRP-2 and GHRP-6. It is prohibited in sport at all times, in and out of competition, named as examorelin (hexarelin) among the GH-releasing peptides in section S2.2.4 of the WADA 2026 Prohibited List.

It switches on the ghrelin receptor in the pituitary gland and the hypothalamus — the same switch the stomach hunger hormone ghrelin uses — which releases a burst of growth hormone. The burst is bigger than the one produced by the body's own growth-hormone-releasing hormone, and the two given together release more than adding them separately would predict. It is not selective: the same injection also raises the stress hormone cortisol, the pituitary signal ACTH that drives it, and prolactin, and researchers traced the cortisol part to vasopressin rather than the usual stress pathway. In heart tissue it binds a second, different protein called CD36; the rodent work behind that finding measured narrowing of the heart's own blood vessels, not how hard the heart squeezes.

Part of the bodyWhat happensHow it is knownKind of evidence

The pituitary gland, at the base of the brain

Hexarelin flips the same switch the stomach hormone ghrelin uses, on the gland that makes growth hormone. That gland is the size of a pea and sits under the brain. Growth hormone comes out in a burst that peaks about 30 minutes after an injection into a vein and is back where it started within four hours. The burst is larger than the one produced by growth-hormone-releasing hormone, the body's own signal for the same job, and giving both together produces more than adding the two separately would predict.

Measured against a dummy injection in 12 healthy adult men in the company's own dose-finding study, and again in 6 healthy men aged 25 to 34 who were also given saline on a separate day.

Measured in people

Source [01]Source [11]

Muscle, body fat and bone

This is what people buy it for, and it is the one thing that was actually measured over months. Twelve healthy older adults injected it under the skin twice a day for 16 weeks and were scanned before and after. Total body fat did not change. Lean body mass did not change. Bone density did not change. Of five markers of bone building and bone breakdown, one marker of collagen formation was higher at 16 weeks and the rest were unmoved. Nobody has ever tested whether it changes strength, in any study, at any amount.

Measured with dual-energy X-ray absorptiometry, the standard body scan, before and after 16 weeks of twice-daily injections in 12 healthy elderly adults. There was no dummy-injection group; each person was compared with themselves.

Measured in people

Source [02]Source [03]

The growth signal in the blood (IGF-1)

Growth hormone works mostly by making the liver release IGF-1, and it is IGF-1 that reaches muscle and bone. In adults this did not happen. Across 20 weeks of measurement, covering 16 weeks of twice-daily injections and 4 weeks after stopping, IGF-1 and its main carrier protein were statistically unchanged. In short children given a nasal spray three times a day for months, IGF-1 did rise, from about 10.4 to about 14.1 nanomoles per litre. The difference between those two results has never been explained by a study designed to explain it.

Measured over 20 weeks in 12 healthy older adults, and separately over up to 8 months in 8 short children aged 4 to 11.6 years. Neither study had a comparison group.

Measured in people

Source [02]Source [04]

The adrenal glands and the milk hormone

An injection into a vein releases not only growth hormone but also the stress hormone cortisol, the pituitary signal ACTH that drives it, and prolactin, the hormone best known for milk production. This is not a rare reaction; it is what the molecule does at those amounts by that route. It rises with the amount given: half a microgram per kilogram of body weight raised cortisol by about 40 per cent, and one microgram per kilogram raised prolactin by about 180 per cent above where it started. Researchers traced the cortisol effect to vasopressin, a water-balance hormone, rather than to the usual stress pathway.

Measured in healthy adult men in a dose-response study, and in a second study of 15 healthy young men in which hexarelin was compared head to head with two other stimulants of the same axis.

Measured in people

Source [12]Source [13]

The heart

A single injection makes the heart squeeze harder for a while, and this appears to have nothing to do with growth hormone. During heart bypass surgery, hexarelin raised the fraction of blood the left chamber pushes out per beat, along with the total blood the heart moved per minute, within ten minutes and for up to 90 minutes. Growth hormone itself, given to a matched group in the same operation, did nothing. The researchers who measured it put it down to receptors on the heart rather than to growth hormone. Hexarelin does also bind a second, different protein on heart tissue called CD36, but the rodent work that found that binding measured a narrowing of the heart's own blood vessels, not a harder squeeze, so it is not an explanation of what was seen here.

Measured during bypass surgery in 24 men with coronary artery disease, split between hexarelin, growth-hormone-releasing hormone, growth hormone and a dummy injection, with heart function watched by an ultrasound probe in the gullet. Seen again in 7 men with growth hormone deficiency and 9 healthy men in an earlier scan study. The CD36 binding was identified in rodent hearts and cells.

Measured in people

Source [14]Source [15]Source [16]

Sleep

It made sleep worse, not better. Seven healthy young men were given four injections through the evening and night, on one occasion hexarelin and on another a dummy injection, with their brainwaves recorded both times. On the hexarelin nights the deepest stage of sleep in the first half of the night was reduced, and the slow brainwave activity that marks deep sleep was lower across the whole night. Growth hormone and prolactin were higher all night; cortisol and ACTH were higher in the first half.

One placebo-controlled crossover study in 7 healthy young volunteers, with sleep measured by electrodes on the scalp rather than by asking people how they slept.

One small study

Source [05]

Appetite

People felt slightly hungrier. In 15 healthy young men who marked their symptoms on a sliding scale during the test, hexarelin produced a small, short-lived increase in appetite. That is the whole of the published human evidence on hunger. Nobody has weighed what anyone then ate.

Recorded on symptom scales during a two-hour hormone test in 15 healthy young men.

One small study

Source [13]

Height, in short children

Two small studies from one hospital gave a nasal spray three times a day to prepubertal short children for six to ten months. Growth sped up, from about 5.3 to about 8.3 centimetres a year in the first study and from about 5.3 to about 7.4 in the second. Skinfold thickness fell and head circumference rose. Neither study had a comparison group, so there is nothing to say how much of that was the drug and how much was ordinary variation in how short children grow. Nothing has been published about these children since 1996.

Two uncontrolled studies from the same Tel Aviv group, in 8 and 7 prepubertal children, each compared with the child's own growth rate before treatment.

One small study

Source [04]Source [17]

The only study that gave hexarelin for months and then measured what people take it for found nothing: after 16 weeks of injections under the skin twice a day in 12 healthy older adults, total body fat, lean body mass, bone mineral density, IGF-1 and IGF binding protein-3 were all statistically unchanged from baseline, while the growth hormone released by the injection itself fell from 19.1 to 10.5 µg/L·h and returned to 19.4 four weeks after stopping (Rahim, O'Neill and Shalet, J Clin Endocrinol Metab 1998; the sample size of 12 comes from the same authors' companion abstract in Growth Horm IGF Res 1998). That study had no dummy-injection group; each person was compared with themselves. What is well established is the short-term hormone effect: in a double-blind placebo-controlled rising-dose study in 12 healthy men, peak growth hormone was 3.9 ng/ml after a dummy injection against 26.9, 52.3 and 55.0 after 0.5, 1 and 2 micrograms per kilogram of body weight (Imbimbo et al., Eur J Clin Pharmacol 1994). Two uncontrolled studies from one Tel Aviv hospital, in 8 and 7 prepubertal short children, reported growth velocity rising from about 5.3 to 8.3 cm/year over periods of up to 8 months in the first and to 7.4 cm/year over 6–10 months in the second, both on a nasal spray and neither with a comparison group. A placebo-controlled crossover study in 7 healthy young men found hexarelin reduced the deepest stage of sleep in the first half of the night (Frieboes et al., Psychoneuroendocrinology 2004). No study has ever measured strength. A search of ClinicalTrials.gov on 3 August 2026 returned zero registered studies for either hexarelin or examorelin.

Growth hormone peaks about 30 minutes after an injection into a vein and is back at the starting level within four hours, the growth hormone clearing from blood with a half-life of about 55 minutes. Give a second injection two hours after the first and the second burst is already smaller. Over weeks the fade is much larger: in short children on a nasal spray the response had halved after seven days, and in older adults injecting twice a day it fell steadily to about 55 per cent of the starting value by 16 weeks. It recovers, at least partly. Four weeks after stopping, the response in adults was back to where it began; three months after stopping, the response in children had risen again but was still below its pretreatment level. What never moved in adults, at any point across 20 weeks, was IGF-1, body fat, lean mass or bone density.

What was measuredWhat happenedIn whomHow it is known

Body fat, lean mass, bone density and IGF-1 after 16 weeks

No significant change in any of them. Total body fat, lean body mass and bone mineral density were statistically unmoved at 16 weeks compared with the start, and so were IGF-1 and IGF binding protein-3 across the full 20 weeks of measurement. One marker of collagen formation in bone was higher at 16 weeks; the other four bone markers were not. There was no dummy-injection group, so each person served as their own comparison.

12 healthy older adults, injecting 1.5 micrograms per kilogram of body weight under the skin twice a day for 16 weeks, followed for 4 further weeks.

Measured in people

Source [02]Source [03]

Growth hormone after a single injection into a vein

Peak growth hormone was 3.9 nanograms per millilitre after a dummy injection, and 26.9, 52.3 and 55.0 after 0.5, 1 and 2 micrograms per kilogram of body weight. The curve had flattened by the 2 microgram dose, meaning more drug bought almost nothing more. Growth hormone peaked around 30 minutes and was back at the starting level within four hours.

12 healthy adult men, each receiving all three amounts and a dummy injection, in a double-blind rising-dose study run by the company developing the peptide.

Measured in people

Source [01]

How much growth hormone the same injection releases after weeks of use

It falls by nearly half and then comes back. The total growth hormone released by a test injection was 19.1 units at the start, 13.1 after one week, 12.3 after four weeks and 10.5 after 16 weeks, measured as micrograms per litre per hour. Four weeks after stopping it was 19.4, statistically no different from where it began. The same fading was recorded independently in short children on a nasal spray: their growth hormone peak fell from about 70.6 to about 34.1 milliunits per litre after only seven days, stayed down for six months of treatment, and rose again three months after stopping.

12 healthy older adults injecting twice a day for 16 weeks, and 7 prepubertal short children using a nasal spray three times a day for 6 to 10 months.

Measured in people

Source [02]Source [17]

How hard the heart squeezes, during bypass surgery

The fraction of blood pushed out of the left chamber per beat rose within ten minutes and stayed up for 90 minutes, as did the amount of blood the heart moved per minute, while the pressure in the vessels feeding the lungs fell. Growth hormone, growth-hormone-releasing hormone and a dummy injection all produced no change at all in the same operation. Heart rate after hexarelin was the same as after the dummy injection.

24 men with coronary artery disease, average age 59.5, under general anaesthetic during bypass surgery, split between hexarelin, growth-hormone-releasing hormone, growth hormone and a dummy injection.

Measured in people

Source [14]

Cortisol and prolactin after a single injection

Both rose with the amount given. Cortisol stepped up by about 40 per cent at half a microgram per kilogram of body weight. Prolactin reached a plateau at about 180 per cent above the starting level at one microgram per kilogram. Giving a small amount of hexarelin together with growth-hormone-releasing hormone produced a very large growth hormone release with a moderate prolactin rise and no cortisol rise at all.

Healthy adult men, given amounts from zero to 1 microgram per kilogram of body weight into a vein.

Measured in people

Source [12]

How much growth hormone comes out depends on how much body fat a person carries

The more fat, the smaller the burst. Total fat mass was the single best predictor of both the peak and the total growth hormone released after an injection under the skin, and it explained about 61 per cent of the difference in peak response between people. Being male or female made no independent difference once body composition was accounted for. None of these people were severely obese, so this is a sliding scale across ordinary bodies, not an effect confined to obesity.

21 healthy elderly adults, 8 of them men, median age 68 with a range of 60 to 81, each given a single injection under the skin and scanned for body composition.

Measured in people

Source [18]

Growth hormone release at different ages

It works best in the middle of life. The growth hormone released by the same 2 microgram per kilogram injection was large in pubertal children and young adults, and only about a third as large in prepubertal children and in people aged 53 to 79, which were similar to each other. In both of those groups an older combination test of arginine plus growth-hormone-releasing hormone released more than twice as much. This is one reason it never became a standard diagnostic test.

6 prepubertal children, 6 pubertal children, 12 young adults aged 22 to 30 and 12 people aged 53 to 79, each compared against other stimulation tests.

Measured in people

Source [19]Source [20]

Deep sleep

Less of it. The deepest sleep stage in the first half of the night was reduced and slow brainwave activity across the whole night was lower, compared with the same men on a dummy injection. Growth hormone and prolactin were higher across the night; the stress hormones ACTH and cortisol were higher in the first half. Leptin and two inflammation markers did not move.

7 healthy young men, each studied on a hexarelin night and a dummy-injection night, given four injections at 22:00, 23:00, midnight and 01:00.

One small study

Source [05]

Height gain in short children

Growth velocity went from about 5.3 to about 8.3 centimetres a year in the first study and from about 5.3 to about 7.4 in the second, with less fat under the skin and a larger head circumference. Neither study had a comparison group, so the only thing these figures are measured against is how fast the same children were growing beforehand.

8 prepubertal short children aged 4 to 11.6 treated for up to 8 months, and 7 prepubertal short children of mean age 7.6 treated for 6 to 10 months, both at the same hospital.

One small study

Source [04]Source [17]

Heart pumping in people whose hearts were already failing

It helped one group and not the other. In 5 people whose weak heart was caused by blocked arteries, the fraction of blood pushed out per beat rose from 22.6 to 26.2 per cent. In 8 people whose heart muscle was weak for other reasons, it did not move, going from 16.7 to 17.7 per cent, even though hexarelin released the same amount of growth hormone in both groups. These were single injections with no dummy-injection group.

13 people with severe heart failure, compared with 7 healthy people and 7 people with growth hormone deficiency studied earlier by the same method.

One small study

Source [15]Source [21]

Muscle and body composition in old dogs

Six old beagles were given hexarelin under the skin for 16 weeks in three blocks with breaks between them. Growth hormone pulses increased, but IGF-1 in blood did not change. A marker of bone breakdown in urine fell while a marker of bone building did not move. In three of the six dogs, some measurements taken from muscle samples improved. Three of six is the sort of split a six-animal study cannot separate from chance.

6 old beagle dogs, 500 micrograms per kilogram of body weight a day, 16 weeks, against untreated young dogs rather than against untreated old dogs.

Only seen in animals

Source [22]

Injected into a vein it also raises the stress hormone cortisol and the hormone prolactin, in proportion to how much is given: about a 40 per cent cortisol rise at half a microgram per kilogram of body weight, and about a 180 per cent prolactin rise at one microgram per kilogram. Under the skin, which is how it is sold, two studies giving it two or three times a day for up to 16 weeks found cortisol unchanged or lower and prolactin unchanged. Given at night it cut the deepest stage of sleep and reduced slow brainwave activity compared with a dummy injection in seven healthy men, which is the opposite of the sleep benefit it is sold for. The growth hormone response fades with repeated use, halving within days on a nasal spray and falling to about 55 per cent of baseline over 16 weeks of injections, then recovering after a break. Published reviews call it generally well tolerated, but that verdict rests on studies mostly a few hours long in supervised volunteers; nothing has been published about use beyond 16 weeks, about the children treated in the 1990s since 1996, about pregnancy, about whether blood sugar or insulin drift over a course, or about what is actually in the vials sold online.

EffectWhat it feels likeHow often

Cortisol and prolactin go up after an injection into a vein

Cortisol is the stress hormone and prolactin is best known for milk production; sustained high levels of either cause their own problems, from raised blood sugar to reduced sex drive and, in men, breast tissue growth. Nobody has established whether short spikes twice a day for months matter. In fact the one study that looked found the opposite of what was feared: after 16 weeks of twice-daily injections the cortisol response to an injection had gone down rather than up, 24-hour cortisol in urine had not changed, and the prolactin response was no different from where it started. Why that happens is unexplained. A separate 24-hour study of injections under the skin found no rise in prolactin, ACTH or cortisol at all, so the reliable rise is the one seen after an injection into a vein.

It is not an occasional reaction, it is what the molecule does at the amounts given into a vein, and it scales with the amount. About a 40 per cent rise in cortisol at half a microgram per kilogram of body weight, and about a 180 per cent rise in prolactin at one microgram per kilogram.

Source [12]Source [23]Source [24]

Worse deep sleep on the nights it is injected

The deepest stage of sleep in the first half of the night was cut, and the slow brainwave activity that marks restorative sleep was lower across the whole night. This runs directly against the common claim that growth hormone peptides improve sleep. A published review of these compounds lists reduced deep sleep as a known effect of hexarelin.

A group difference in the only study that recorded brainwaves: 7 men, each studied once on hexarelin and once on a dummy injection.

Source [05]Source [25]

Feeling hungrier

This is the same switch the hunger hormone ghrelin uses, so an appetite effect is expected. What is not known is whether it is large enough to change what anyone eats, because no study has measured food intake.

A small, short-lived increase recorded on symptom scales in 15 healthy young men during a two-hour test.

Source [13]

Anything that takes longer than 16 weeks to appear

Two published reviews describe hexarelin as generally well tolerated with no serious side effects reported. That is a true summary of studies that were mostly a few hours long, in people who were being watched by researchers, at amounts far below the ones described on bodybuilding forums. It is not the same statement as safe. No two-year animal cancer study of hexarelin has been published, and the question of what repeatedly stimulating a growth pathway does over years has not been asked of this compound.

Not measured. Sixteen weeks in 12 healthy older adults is the longest anyone has been followed in a published study, and most human studies of hexarelin gave one injection.

Source [02]Source [10]Source [25]

These are the amounts the studies below gave their participants, and they are here as facts about those studies. They are not a recommendation, not a starting point and not a range to pick from. What a person should take, if anything, is a question for a doctor who knows them.

Imbimbo and colleagues 1994, the developing company's own first-in-human dose-finding study in healthy men, against a dummy injection

Single injections into a vein of 0.5, 1 and 2 micrograms per kilogram of body weight, given in rising order with a dummy injection slotted in at random.

Single injections, with blood taken for 240 minutes after each.

Source [01]

Rahim, O'Neill and Shalet 1998, the only study that gave hexarelin for months and then scanned people, in 12 healthy older adults

1.5 micrograms per kilogram of body weight, injected under the skin twice a day.

16 weeks, with measurements continuing to week 20.

Source [02]

Laron and colleagues 1995, whether a nasal spray would make short children grow, in 8 prepubertal children aged 4 to 11.6

60 micrograms per kilogram of body weight as a nasal spray, three times a day.

Up to 8 months.

Source [04]

Frieboes and colleagues 2004, what it does to sleep, in 7 healthy young men, against a dummy injection

Four injections of 50 micrograms each, not adjusted for body weight, given at 22:00, 23:00, midnight and 01:00.

One night, with a separate dummy-injection night for comparison.

Source [05]

Broglio and colleagues 2002, what a single injection does to the heart, in 24 men undergoing bypass surgery

2 micrograms per kilogram of body weight into a vein, once, compared against growth-hormone-releasing hormone, growth hormone and a dummy injection.

A single injection, with heart function watched for 90 minutes.

Source [14]

Maccario and colleagues 2002, whether spreading injections across a day raises 24-hour growth hormone, in 6 normal young men

1.5 micrograms per kilogram of body weight under the skin, either two or three times in the day.

24 hours, with blood taken every 20 minutes.

Source [24]

What people report

• Whether it adds any strength — no published study has tested strength, in any person, at any amount.
• Whether it does anything in someone who trains: every participant in every published study was a patient, a healthy volunteer or a child, never an athlete.
• Whether the amounts described on forums, cycled for years, do what 16 weeks of the studied amount did not.
• What happens after 16 weeks, which is as long as any published human study has run.
• Whether the fading growth hormone response recovers after more than one cycle: recovery was checked once, four weeks after a single 16-week course.
• Why IGF-1 rose in children treated for months and did not move in adults treated for 16 weeks.
• What it does to blood sugar or insulin over weeks in a person — no published human study of hexarelin has followed either as an outcome.
• Whether it helps any injury or tendon heal — never measured, in any species.
• Whether repeatedly spiking cortisol and prolactin twice a day matters: the one study that looked found the cortisol response went down rather than up after 16 weeks, and nobody has explained that.
• Whether the worse deep sleep seen on one night persists, improves or gets worse over weeks of use.
• Whether the heart effect means anything beyond 90 minutes: every heart study gave a single injection.
• Whether the pituitary gland becoming less responsive over weeks also happens at the heart receptor, which is a different protein.
• Whether long use affects cancer risk: no two-year animal cancer study of hexarelin has been published.
• Whether women respond differently to anything except the size of the growth hormone burst, where body fat mattered and sex did not.
• What is in the vials sold online: no published chemical analysis of a hexarelin product bought from a seller exists.
• What happens when it is injected alongside the anabolic steroids and other peptides people stack it with — no published study has given it together with any of those.
• What became of the 15 short children treated in the 1990s: nothing has been published about them since 1996.
• Whether it is safe in pregnancy or breastfeeding, which has not been studied at all.

Does hexarelin work?

It depends entirely on what you mean by work. As a way of releasing growth hormone it works better than almost anything else that has been tested in people: one injection can take growth hormone from about 4 to about 55 nanograms per millilitre within half an hour. As a way of changing a body it did not work. The only study that gave it twice a day for 16 weeks and then scanned people found body fat, lean mass, bone density and the growth signal IGF-1 all unchanged from where they started.

Source [01]Source [02]

Is hexarelin legal?

It is not an approved medicine in the EU, the United States or anywhere else, so it cannot legally be sold or advertised to the public as something to take. What is sold online is labelled as a research chemical, which is the wording used to sell an unapproved substance without making a medical claim. In sport it is banned outright: the World Anti-Doping Agency's 2026 Prohibited List names examorelin, hexarelin's official drug name, in section S2.2.4, and everything in section S2 is prohibited at all times, in and out of competition.

Source [06]Source [10]

What are the side effects of hexarelin?

The measured ones are that every injection also raises the stress hormone cortisol and the hormone prolactin, in proportion to how much is given, and that injections at night reduced the deepest stage of sleep in the only study that recorded brainwaves. Some people felt slightly hungrier. Published reviews call it generally well tolerated, but that verdict rests on studies that were mostly a few hours long, in supervised volunteers. Nothing has been published about anyone taking it for longer than 16 weeks.

Source [05]Source [12]Source [13]

Hexarelin vs ipamorelin: what is the difference?

They press the same switch, but with different side traffic. Hexarelin releases more growth hormone, and it also raises cortisol and prolactin every time. Ipamorelin was deliberately designed not to do that, and in its original animal characterisation it released growth hormone without raising stress hormones more than the body's own signal does. Neither has a published study showing it changes muscle or body fat in a person, and both are on the World Anti-Doping Agency's prohibited list at all times.

Source [06]Source [12]Source [26]

Can you buy hexarelin?

It is sold online, labelled as a research chemical rather than as a medicine, and there is no licensed product anywhere to compare it against. Nobody has published a chemical analysis of a hexarelin vial bought from a seller, so what is actually in one is unknown. In the United States it cannot be made up by a pharmacy either: it does not appear anywhere on the regulator's list of substances nominated for pharmacy compounding, which was last updated in May 2026 and does list the related peptides GHRP-2 and GHRP-6.

Source [08]Source [10]

Does hexarelin stop working over time?

Yes, partly, and it comes back. In 12 healthy older adults injecting twice a day, the growth hormone released by a test injection fell from 19.1 to 10.5 units over 16 weeks, and was back to 19.4 four weeks after stopping. In short children on a nasal spray the response had already halved after seven days of treatment and had risen partway back three months after stopping. Even within a single day the effect fades: a second injection given two hours after the first releases less than the first did.

Source [02]Source [11]Source [17]

Does hexarelin raise IGF-1?

In adults, no. Across 20 weeks of measurement in the only long study, IGF-1 and its main carrier protein did not change significantly, even though every injection released growth hormone. In short children given it for months, IGF-1 did rise, from about 10.4 to about 14.1 nanomoles per litre. Nobody has run the study that would explain why the two results differ.

Source [02]Source [04]

Is hexarelin good for the heart?

A single injection makes the heart squeeze harder for about an hour and a half, and that effect is real and controlled: during bypass surgery it raised how much blood the heart moved, while growth hormone and a dummy injection in the same operation did nothing. But every heart study of hexarelin gave one injection and watched for at most 90 minutes. Nobody has tested whether repeating it does anything useful over weeks, and in people whose heart muscle was weak for reasons other than blocked arteries it did not help even once.

Source [14]Source [15]Source [21]

Why did hexarelin never become a medicine?

It was tested in people through the 1990s, mostly as a way of releasing growth hormone and as a possible diagnostic test, and then development stopped. There is no registered trial of it: a search of the ClinicalTrials.gov registry in August 2026 returned zero studies for either hexarelin or examorelin. The published record offers two plain reasons. The growth hormone response fades with repeated use, and the one study that gave it for 16 weeks and measured something that matters found nothing had changed.

Source [02]Source [03]Source [09]

1. [01]Imbimbo BP et al. Growth hormone-releasing activity of hexarelin in humans. A dose-response study. Eur J Clin Pharmacol 1994;46(5):421-5 (double-blind, placebo-controlled, 12 healthy men, run by Mediolanum Farmaceutici) (1994)
2. [02]Rahim A, O'Neill PA, Shalet SM. Growth hormone status during long-term hexarelin therapy. J Clin Endocrinol Metab 1998;83(5):1644-9 (16 weeks; IGF-1, IGFBP-3, body fat, lean mass and bone density all unchanged) (1998)
3. [03]Rahim A, Shalet SM. Does desensitization to hexarelin occur? Growth Horm IGF Res 1998;8 Suppl B:141-3 (companion abstract giving the sample size, 12 healthy elderly individuals) (1998)
4. [04]Laron Z et al. Intranasal administration of the GHRP hexarelin accelerates growth in short children. Clin Endocrinol (Oxf) 1995;43(5):631-5 (8 children, no control group) (1995)
5. [05]Frieboes RM et al. Hexarelin decreases slow-wave sleep and stimulates the secretion of GH, ACTH, cortisol and prolactin during sleep in healthy volunteers. Psychoneuroendocrinology 2004;29(7):851-60 (2004)
6. [06]WADA: World Anti-Doping Code International Standard – Prohibited List 2026, section S2.2.4, GH-releasing peptides, naming examorelin (hexarelin); S2 prohibited at all times (2026)
7. [07]PubChem: Hexarelin (CID 6918297) – C47H58N12O6, 887.0 g/mol, IUPAC name showing D-2-methyl-tryptophan, D-phenylalanine and a C-terminal amide; synonyms include Examorelin [INN] and CAS 140703-51-1
8. [08]FDA: Bulk Drug Substances Nominated for Use in Compounding Under Section 503A, updated 14 May 2026 (hexarelin absent; GHRP-2 and GHRP-6 listed) (2026)
9. [09]ClinicalTrials.gov API v2 search for hexarelin: totalCount 0 (checked 3 August 2026; examorelin also returns 0)
10. [10]Dominikowski J et al. The emerging landscape of performance-enhancing peptides modulating the GH-IGF1 axis. Front Endocrinol 2026 (free full text; hexarelin summarised as phase I/II only, no body-composition trials, sold as a research compound) (2026)
11. [11]Massoud and colleagues, the effect of repeated administration of hexarelin and growth hormone releasing hormone on growth hormone responsivity (Clin Endocrinol) (1996)
12. [12]Massoud, Hindmarsh and Brook, hexarelin-induced growth hormone, cortisol and prolactin release, a dose-response study (J Clin Endocrinol Metab) (1996)
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