GHRP-2

A synthetic six-amino-acid peptide, given the official drug name pralmorelin, that makes the pituitary gland release a burst of growth hormone. It is the only compound of its family that any national medicines regulator has ever approved — and the approval is narrow: Japan authorised pralmorelin hydrochloride as GHRP Kaken 100 for injection in 2004, with one indication printed on the label, "diagnosis of growth hormone secretion deficiency", delivered as a single 100-microgram injection into a vein. Japan's own drug classification files it under category 7223, inside a class titled "agents not mainly for therapeutic purpose". It is not approved to treat anything, in Japan or anywhere else. Its chain is D-Ala-D-2-naphthylalanine-Ala-Trp-D-Phe-Lys-NH2: three of the six building blocks break the standard one-letter code — two are mirror-image forms and one is a naphthylalanine that does not occur in nature and has no letter at all — and the chain ends in an amide cap, so the sequence field is deliberately left empty rather than filled with a string that would describe a different molecule. PubChem gives C45H55N9O6 and 818.0 g/mol for the free base (CID 6918245, CAS 158861-67-7). Outside Japan it is sold online as a freeze-dried powder labelled for research use only.

Sold as

Injected into a vein in the approved Japanese diagnostic test and in most published studies. Studies have also given it under the skin as a single injection, as a daily injection, and as a continuous infusion by pump; as a nasal spray in short children; and by mouth in children. Sold online as a freeze-dried powder for injection under the skin.

Legal status in the EU

Not approved as a medicine in the EU or the United States, and no trial of it is registered on ClinicalTrials.gov. It is approved in Japan, and only there, and only as a diagnostic: pralmorelin hydrochloride was authorised as 注射用GHRP科研100 (GHRP Kaken 100 for injection, approval number 21600AMZ00573, on sale February 2005, package insert still current at its July 2025 revision), with the single indication "diagnosis of growth hormone secretion deficiency" and Japanese therapeutic category 7223, diagnostic reagents for endocrine function, inside a class titled "agents not mainly for therapeutic purpose". That is authorisation to run a blood test, not to treat a condition. In the United States, the FDA placed GHRP-2 for injectable and nasal routes in category 2 of the 503B bulk substances list — substances that raise significant safety risks — on 29 September 2023, so an outsourcing facility cannot compound it for injection; on the 503A pharmacy compounding list (updated 14 May 2026) it sits in category 3, nominated without adequate support. A search of Drugs@FDA via the openFDA API for pralmorelin returns no approved product. In Sweden, the doping law (1991:1969) covers in its own words chemical substances that increase the production or release of growth hormone, and makes importing, possessing or using such substances outside medical or scientific purposes a criminal offence. Named by name on the WADA Prohibited List 2026, section S2.2.4, as "GHRP-2 (pralmorelin)" — prohibited at all times, in and out of competition.

It switches on the ghrelin receptor — the same switch the stomach's hunger hormone ghrelin uses — in the pituitary gland and the hypothalamus, and the pituitary releases a burst of growth hormone that peaks within 15 to 60 minutes and is gone within a couple of hours. That is a different route from the body's own growth-hormone-releasing hormone, GHRH, and it does not depend on it: in 11 people born with a mutation that switches off the GHRH receptor, GHRP-2 still produced a 4.5-fold rise in growth hormone, against a 79-fold rise in 8 healthy controls (Gondo et al., JCEM 2001) — so the receptor is not required, even though the response is far larger when it works. It is not selective. The same injection drives the chain that ends in the stress hormone cortisol and raises the milk hormone prolactin, and in 47 patients investigated for pituitary and hypothalamic disease the ACTH and cortisol responses to GHRP-2 showed no correlation at all with the standard CRH stress test in the same people, which the authors read as GHRP-2 acting on the pituitary directly. In animals it also acts on the brain's appetite centres, and in people it measurably increases how much food they eat.

Part of the bodyWhat happensHow it is knownKind of evidence

The pituitary gland, at the base of the brain

GHRP-2 latches onto the same switch that the stomach hunger hormone ghrelin uses, and the pituitary gland releases a burst of growth hormone. It is fast and short: in the Japanese registration studies the peak arrived between 15 and 60 minutes after the injection in every single person tested, and among the deficient patients who responded at all the average time to the peak was about 26 minutes. The size of the burst is what the approved Japanese test is built on — in healthy people the peak averaged about 85 nanograms per millilitre, and in people whose pituitary gland had already been shown to be failing it averaged about 1.4. That gap is wide enough that a cut-off of 15 is used to tell the two groups apart.

Measured in 77 healthy people and 58 patients in the study that supported the Japanese approval, and in the approved product label's own figures of 89 healthy people and 60 patients — the same programme, counted slightly differently in the paper and on the label. Repeated since in hundreds of adults and children in Japan, and in the United States, Belgium, the Netherlands, Italy and Chile.

Measured in people

Source [01]Source [02]Source [17]

Appetite, and how much a person eats

This is the one thing GHRP-2 has been shown to do in people that a person would actually notice. Given as a slow drip under the skin for four and a half hours and followed by a buffet lunch, it made people hungrier before the meal and made them eat more of it — about a third more food than after a dummy drip — and the more that was given, the more they ate. It did not change what they chose to eat, and it did not change how full they said they felt afterwards. Being obese made no difference: obese participants responded as strongly as lean ones. Children given it by mouth for a year reported the hunger too, but only for the first six months.

Measured twice in the same laboratory: first in 7 lean healthy men against a dummy drip, then in 19 people — 10 lean and 9 obese — in a double-blind randomised study where each person had a high dose, a low dose and a placebo on three separate visits. Also reported by 7 of 10 growth-hormone-deficient children during 12 months of tablets, in a study with no comparison group.

Measured in people

Source [04]Source [05]Source [22]

The stress hormone cortisol, and the milk hormone prolactin

GHRP-2 is not selective. The same injection that releases growth hormone also switches on the chain that ends in cortisol, the body's main stress hormone, and pushes up prolactin, the hormone that drives milk production. In 42 healthy men given a placebo injection on one morning and GHRP-2 on another, peak cortisol was about 616 nanomoles per litre after GHRP-2 against about 420 after saline, plain GHRH or somatostatin. A direct head-to-head comparison in young adults found GHRP-2 and hexarelin raised cortisol and ACTH about as much as a dose of the body's own stress-hormone trigger, hCRH. In 47 patients being investigated for pituitary and hypothalamic disease, the ACTH and cortisol rises after GHRP-2 tracked nothing at all in the standard stress-hormone test given to the same people, which the authors read as GHRP-2 pushing ACTH out of the pituitary gland directly rather than through the brain above it.

Measured in 42 healthy men in a double-blind placebo-controlled study, in 6 young and 6 elderly adults in a head-to-head comparison with hexarelin and with the standard hormone triggers, and in small hospital series of 6, 15 and 47 patients with pituitary or hypothalamic disease.

Measured in people

Source [08]Source [16]Source [23]

How quickly the effect wears off with repeated use

It fades, and fast. Nine healthy young men given the same 100-microgram injection every day for five days released less growth hormone on each successive test: the peak fell from about 83 nanograms per millilitre on day one to 59 on day three and 51 on day five, and the total amount released over three hours nearly halved. The pituitary gland was still responding — it simply responded less. Running the peptide in continuously instead of in daily shots slowed this down but did not stop it: over 30 days the growth hormone released fell from more than three times the placebo level on day one to about 1.8 times by days 14 and 30.

Measured in 9 healthy young men across 5 days of daily injections, each man compared with his own first day, and in 17 healthy older adults across 30 days of continuous infusion compared against saline.

Measured in people

Source [06]Source [07]

The body's own protein, in people who are seriously ill

This is the only setting where anyone measured whether GHRP-2 does what people take it for — stop the body eating its own muscle — and did it against a placebo. In 33 men who had been critically ill in intensive care for weeks, GHRP-2 alone switched the growth hormone system back on and returned IGF-1 to normal, but it did not slow protein breakdown and it did not raise the blood marker of new bone being built. The combinations that added thyroid and sex-hormone triggers on top of it did both. Adding the peptide back to the hormone picture was not enough on its own.

Measured in 33 critically ill men randomly assigned to placebo, GHRP-2 alone, GHRP-2 with a thyroid trigger, or GHRP-2 with a thyroid trigger and pulses of a sex-hormone trigger, for 5 days, with blood sampled every 20 minutes overnight.

Measured in people

Source [03]Source [26]

IGF-1, the growth signal that growth hormone actually works through

Growth hormone does almost nothing to the body directly. It works by telling the liver and other tissues to make a second signal called IGF-1, and IGF-1 is what a doctor measures to see whether growth hormone is doing anything. Here the published studies split cleanly on how the compound was given. Every study that gave GHRP-2 in separate doses — a daily injection in healthy young men for five days, daily injections in children for eight months, a nasal spray in children for up to two years — found IGF-1 did not rise. The one study that ran it in continuously, through a pump under the skin for 30 days, found IGF-1 rose within a day and stayed up for the full month. The way it is sold and self-injected is the intermittent way.

Measured in 9 healthy young men over 5 days of daily injections, in 6 growth-hormone-deficient children over 8 months of daily injections, in 15 short children on a nasal spray for 6 to 24 months, and in 17 healthy older men and women during 30 days of continuous infusion. Only the last of these found any change, and its IGF-1 comparison was against each person's own starting value rather than against a placebo group.

Studies in people disagree

Source [06]Source [07]Source [09]Source [24]

Growth, in short children

Children given GHRP-2 grew faster while they were taking it, in two small studies from the 1990s that had no comparison group. Fifteen short children on a nasal spray went from growing 3.7 centimetres a year to 6.1 at six months, and the six who stayed on it for 18 to 24 months were still growing at 6.0. Six growth-hormone-deficient children on daily injections grew faster during treatment than in the periods before and after it. In both studies the growth signal IGF-1 did not change, which the authors of the injection study took as a sign the effect of each dose was too brief, and they concluded that a longer-acting form would be needed before this could be a therapy. It never became one.

Seen in 15 children on a nasal spray for 6 to 24 months and in 6 children on daily injections across four 2-month dose steps. Neither study had a control group; each child was compared with their own growth rate before treatment. No child was randomised, and no study has ever compared GHRP-2 against the growth hormone injections that are the standard treatment.

One small study

Source [09]Source [24]

Muscle and body fat

Nobody has measured either, in anyone, in any published study. The online material sells GHRP-2 for body composition and the published record contains no measurement of body composition at all — not a scan, not a set of skinfolds, not a strength test. The closest anything comes is a look back through the notes of a private clinic in Texas, where 105 men on testosterone were prescribed a three-peptide mixture containing GHRP-2 for lean mass and fat loss; only 14 had taken it as prescribed, their IGF-1 rose over about four and a half months, and their muscle and fat were never measured. In children taking it by mouth for a year, body mass index drifted up by an amount too small to be statistically distinguishable from no change at all.

Not measured. The 14-man clinic review had no control group, no randomisation and no body-composition measurement; the 12-month children's study measured body mass index and found no significant change.

Claimed, never tested

Source [18]Source [22]Source [25]

In the only randomised, placebo-controlled trial that gave GHRP-2 as a treatment, it failed at the job it was given: 33 men with prolonged critical illness were randomised to five days of placebo (7), GHRP-2 alone (9), GHRP-2 with TRH (9) or those plus GnRH pulses (8), and GHRP-2 alone did not reduce protein breakdown and did not raise the bone-formation marker osteocalcin, while both combinations containing it did — and by day 5 blood lactate and white cell count were higher on GHRP-2 alone than on the three-hormone regimen (Van den Berghe et al., Clin Endocrinol 2002). Everything else in the human record is hormone measurement or diagnosis. Japan's 2004 approval rests on two uncontrolled studies: peak growth hormone averaged 84.6 µg/L in 77 healthy people against 1.36 µg/L in 58 patients with severe deficiency (Chihara et al., Eur J Endocrinol 2007), and in 71 patients given all three tests it identified 81.3% of the severely deficient and cleared 94.5% of the rest, catching fewer deficient patients than the arginine test (Kinoshita et al., Endocr J 2013). Two things a person would actually notice have been measured. Appetite, against a control arm: 7 lean men ate 32.5 against 24.2 kcal per kg after GHRP-2 versus saline (Laferrère et al., JCEM 2005), and in a double-blind study of 10 lean and 9 obese people food intake rose 10.2% on a low dose and 33.5% on a high dose against placebo (Obesity 2006). And growth: height velocity went from 3.7 to 6.1 cm/year in 15 short children on a nasal spray, with no control group (Pihoker et al., J Endocrinol 1997). Repeated dosing does poorly. Nine healthy men given 100 µg under the skin daily for 5 days released less each time — peak GH 83, then 59, then 51 µg/L — and IGF-1 never moved (22, 25, 23, 25, 23, 24 nmol/L across six days; Nijland et al., Eur J Endocrinol 1998). IGF-1 also failed to rise over 8 months of daily injections in 6 children and up to 2 years of nasal spray in 15 more. Only 30 days of continuous infusion by pump in 17 older adults raised it, and that study measured no body composition (Bowers et al., JCEM 2004). No published study has ever measured muscle, strength or body fat in a person taking GHRP-2; the nearest thing is a retrospective review of 14 men at a Texas clinic on a three-peptide mixture, where IGF-1 rose over about 134 days and body composition was never recorded. A ClinicalTrials.gov API v2 search on 3 August 2026 returned totalCount 0 for GHRP-2, GHRP2, pralmorelin, KP-102, GPA-748 and the quoted phrase "growth hormone releasing peptide 2", both as an intervention and as a general term, against a control query returning 757 studies for semaglutide.

One dose is over in an afternoon. Growth hormone starts climbing within minutes of an injection into a vein, peaks somewhere between 15 and 60 minutes, and the peptide itself is half gone from the blood in about 25 to 41 minutes. Roughly 2 per cent leaves in the urine unchanged over the first day; most of it goes out through the bile. Repeated dosing is where it gets interesting: with a separate injection each day the growth hormone response is already measurably smaller by day three and about 40 per cent smaller by day five, and IGF-1 — the signal growth hormone works through — never moves at all, over five days in adults or eight months in children. Run in continuously through a pump instead, IGF-1 rises within a day and holds for the 30 days anyone has looked. Nobody has published what happens after that, in any dosing pattern.

What was measuredWhat happenedIn whomHow it is known

How much people ate at a free-choice meal

Lean healthy men ate 32.5 kilocalories per kilogram of body weight after a GHRP-2 drip against 24.2 after a saline drip — about 36 per cent more, and every man ate more. In the larger double-blind study, food eaten rose 10.2 per cent above placebo on the low dose and 33.5 per cent above placebo on the high dose. What people chose to eat did not change, and neither did how full they said they felt after the meal.

First 7 lean healthy men, each compared with himself on a saline day; then 19 people — 10 lean, 9 obese — each given a high dose, a low dose and a placebo on three separate visits in random order, with neither the participant nor the researcher knowing which was which.

Measured in people

Source [04]Source [05]

Telling apart adults who can still make growth hormone from adults who cannot

Peak growth hormone after a single 100-microgram injection was 84.6 nanograms per millilitre on average in healthy people and 1.36 in patients already known to have severe growth hormone deficiency. Every person tested reached their peak within 60 minutes. Repeating the test in the same person gave a similar answer, and being older or heavier shifted the result only slightly. A cut-off of 15 nanograms per millilitre matched the cut-off of 3 used in the old insulin test.

77 healthy subjects and 58 patients whose growth hormone deficiency had already been confirmed by the old insulin test. The approved product label gives the same average values for slightly larger groups of 89 and 60.

Measured in people

Source [01]Source [02]

The test compared head-to-head against the old standard test

In 71 patients who had all three tests, the median peak growth hormone was 28.9 nanograms per millilitre with GHRP-2, 9.4 with the old insulin test and 4.4 with arginine. Judged against the insulin test, the GHRP-2 test correctly identified 81.3 per cent of the people who genuinely had severe deficiency and correctly cleared 94.5 per cent of those who did not; the arginine test caught more of the deficient people, 93.8 per cent, but wrongly flagged more of the healthy ones. So GHRP-2 produces the biggest hormone response of the three and is the most likely of the three to miss someone.

71 adults aged 18 to 65 awaiting surgery for a pituitary tumour, each given the insulin test, the arginine test and the GHRP-2 test.

Measured in people

Source [17]

Whether the body actually broke down less of its own protein, in critically ill men

It did not, on GHRP-2 alone. The measure of protein breakdown fell in the men given GHRP-2 together with a thyroid trigger and pulses of a sex-hormone trigger, and in those given GHRP-2 with the thyroid trigger, but not in those given GHRP-2 by itself. The blood marker of new bone being built rose only in the three-hormone group. GHRP-2 alone did switch growth hormone back on and normalise IGF-1 — the hormone changed, the outcome did not. On day 5, lactate in the blood and the white-cell count were higher in the men on GHRP-2 alone and on GHRP-2 with the thyroid trigger than in the three-hormone group.

33 men who had been critically ill in intensive care long enough for their hormone systems to shut down, randomly assigned to 5 days of placebo (7 men), GHRP-2 alone (9), GHRP-2 plus a thyroid trigger (9), or those two plus pulses of a sex-hormone trigger (8). The same group's earlier crossover study, in 14 patients, describes that population as critically ill for 40 days on average.

Measured in people

Source [03]Source [26]

The stress hormone cortisol after a single injection

Peak cortisol was 616 nanomoles per litre after GHRP-2 against a shared average of 420 after saline, plain GHRH or somatostatin in the same men. Adding arginine and GHRH on top of GHRP-2 pushed it to 868. Baseline cortisol before any injection did not differ between conditions, so the rise is the peptide's doing.

42 healthy men, sampled every 10 minutes for 5 hours, each given saline and each of the stimulants on separate fasting mornings in a double-blind randomised design.

Measured in people

Source [08]

IGF-1 and the bone marker after five days of daily injections

IGF-1 did not move: it read 22, 25, 23, 25, 23 and 24 nanomoles per litre on the six mornings of the study. Osteocalcin, a blood marker of bone being built, did rise, from 3.2 to 4.2 micrograms per litre. The growth hormone burst itself shrank across the same five days, from a peak of 83 nanograms per millilitre to 51. There was no placebo group; each man was compared with his own first day.

9 healthy young men given 100 micrograms under the skin once a day for 5 days.

One small study

Source [06]

IGF-1 after 30 days of continuous infusion

Growth hormone secretion was more than three times the saline level on day 1 and still about 1.8 times it on days 14 and 30. IGF-1 rose to a steady plateau by day 1 and held it through day 30, and two of its carrier proteins rose by day 14 or 30. The routine safety blood tests stayed normal. The growth hormone comparison was against saline; the IGF-1 comparison was against each person's own starting value, not against a placebo group.

17 healthy older men and women given 1 microgram per kilogram of body weight per hour, continuously under the skin, for 30 days.

One small study

Source [07]

How fast short children grew

Height velocity went from 3.7 centimetres a year before treatment to 6.1 at six months on a nasal spray, and the six children who stayed on it for 18 to 24 months were growing at 6.0. There was no control group and no randomisation, so the comparison is each child against their own earlier growth rate, and short children under close medical attention can speed up for reasons that have nothing to do with the drug. IGF-1 and its main carrier protein did not change in the same children.

15 children with height more than 2 standard deviations below average, poor growth and low IGF-1; half of them growth hormone deficient, half with short stature of no known cause.

One small study

Source [09]

Whether it hides growth hormone doping from the standard sports test

It does. The test that catches injected growth hormone works by comparing two natural forms of the hormone in blood; injecting growth hormone pushes that ratio up. Adding a single 100-microgram GHRP-2 injection dragged the raised ratio back down to 39.9 to 43.9 per cent of where the growth hormone injection had put it. GHRP-2 given on its own did not move the ratio at all, because it raises both forms together. The compound itself and one of its breakdown products remain findable in urine during the period when the ratio is being masked.

Japanese men: 5 given growth hormone alone, 10 given GHRP-2 alone, 10 given both, against a reference population of 100.

One small study

Source [27]

The only counted side-effect list that exists is Japan's approved label, and it describes a single injection given fasting and lying down in hospital, with no placebo figure printed beside any of it: a flush of heat in 16.0 per cent, with a raised white cell count and audible gut rumbling in the same 5 per cent and over column but with no number printed beside them; at 0.1 to 5 per cent low blood pressure, sweating, cold sweat, dry mouth, nausea, stomach discomfort, bloating, hunger, sleepiness, tiredness and unsteadiness; and at unrecorded frequency a rise in the liver enzyme ALT. The label forbids the drug in women who are pregnant or may be pregnant, tells doctors to weigh the value of the test against continued breastfeeding because it passes into milk in rats, states that no study has been done in babies or children under four, and records that drugs of this kind given to people with a pituitary tumour have been followed by sudden bleeding into the tumour with loss of vision, headache and vomiting. It is not selective: peak cortisol was 616 nmol/L after GHRP-2 against a grand mean of 420 after saline, GHRH or somatostatin in 42 healthy men in a double-blind placebo-controlled study, so the widely repeated idea that GHRP-2 is the clean member of this family is not what the measurements show. The US regulator says it is aware of reports of serious adverse events in people who received GHRP-2 — increased insulin requirement to maintain blood glucose, death of critically ill study subjects, infection and pancreatitis — and states in the same sentence that causality has not been established; it names no study, so which studies those were cannot be checked. Nothing is known beyond 30 days of exposure in an adult. Powders seized by Danish customs and a vial examined at Poland's National Medicines Institute both contained a glycine-extended version of GHRP-2 rather than GHRP-2 itself, and nobody has studied what that does in a person.

EffectWhat it feels likeHow often

Pituitary apoplexy — sudden bleeding into a pituitary tumourSerious

The label states that when drugs of this kind have been given to people with a pituitary tumour, sudden bleeding or infarction inside the tumour has been reported, with loss of vision or of part of the field of vision, headache and vomiting. This is a medical emergency. It matters more here than for most compounds on this register, because the people given GHRP-2 legitimately are precisely the people with pituitary disease.

Frequency not established. The approved Japanese label carries it as a warning based on reports with similar drugs, not on cases seen with GHRP-2 itself.

Source [01]

The serious events the US regulator says it has been told about, without saying whereSerious

When the US FDA placed GHRP-2 on its list of compounding substances that may present significant safety risks on 29 September 2023, it wrote that it is aware of reports of serious adverse events in patients who received GHRP-2, including increased insulin requirement to maintain the blood glucose level, death of critically ill study subjects, infection and pancreatitis — and that causality has not been established. The FDA names no study and gives no numbers, so this register cannot tell you which studies those were or how many people were involved. Both halves of the sentence are printed because printing either one alone would misrepresent it.

Not counted anywhere public. The regulator lists them as reports it is aware of and says in the same sentence that causality has not been established.

Source [10]

A flush of heat through the body

A wave of warmth shortly after the injection. It appears on the approved product label, which means it was collected in the studies the Japanese regulator reviewed, and those studies gave one injection to people who had fasted and were lying down.

16.0 per cent of people in the Japanese registration data — the commonest thing reported, and the only entry in the label's 5 per cent and over column that carries a number at all. Audible gut rumbling and a raised white cell count sit in that same column without one. There is no placebo figure to compare any of it against.

Source [01]

Low blood pressure, sweating, cold sweat and light-headedness

Grouped together because they tend to arrive together and because the approved test is given to someone lying down on an empty stomach, which is itself a set-up for feeling faint. The label also lists dry mouth, a feeling of being dazed, tiredness and unsteadiness in the same band.

Each listed at between 0.1 and 5 per cent on the approved Japanese label. No placebo group.

Source [01]

Feeling sick, stomach discomfort, bloating and hunger

Nausea, an uncomfortable feeling in the stomach and a bloated abdomen. Hunger is listed among them, which is the same effect the appetite studies measured deliberately — on a diagnostic label it is an unwanted symptom, and to someone buying the compound online it is the reason for buying it. Audible gut rumbling is listed higher, in the label's 5 per cent and over column, and stomach pain at unknown frequency.

Each between 0.1 and 5 per cent on the approved Japanese label.

Source [01]

Sleepiness

Drowsiness after the injection. Dizziness is listed separately at unknown frequency. The label warns that the test must be done with the person resting, because stress and exercise change growth hormone readings.

Between 0.1 and 5 per cent on the approved Japanese label.

Source [01]

A rise in the liver enzyme ALT, and shifts in the white blood cell count

These are blood-test changes rather than something a person feels, picked up because the registration studies took blood before and after. What none of them tells you is what happens to these readings after weeks of repeated injections, because that study does not exist.

A raised white cell count sits in the label's 5 per cent and over column, with no percentage printed beside it; the ALT rise and the shifts in the proportions of the different white cell types are both listed at unknown frequency.

Source [01]

A rise in the stress hormone cortisol and in prolactin

Prolactin is the hormone that drives milk production, and a lasting rise can affect periods, sex drive and erections. Cortisol is the body's main stress hormone. A head-to-head study found GHRP-2 raises both about as much as hexarelin does, and raises cortisol and ACTH about as much as a dose of the body's own stress trigger — so the widely repeated idea that GHRP-2 is the clean one in this family is not what the human measurements show. Nobody has measured what either hormone does over weeks of repeated use.

Measured rather than counted: peak cortisol about 616 nanomoles per litre after GHRP-2 against about 420 after a placebo injection in 42 healthy men.

Source [08]Source [23]

Anything that takes more than a month to appear

Almost every published human study of GHRP-2 gave one injection and took blood for two hours. Nothing is known about repeated injections over months in a healthy adult: not what happens to blood sugar, not whether the immune system starts making antibodies against the peptide, not what a raised growth hormone level does over a year. The US regulator's concerns are that a compounded injection of this peptide may provoke an immune reaction because the peptide can clump and carry related impurities, and that GHRP-2 contains a building block not found in nature, which makes it harder to characterise chemically in the first place.

Not measured. The longest published exposure in an adult is 30 days of continuous infusion in 17 people; the longest in anyone is 12 months of tablets in 10 children.

Source [07]Source [10]

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.

The approved Japanese diagnostic test — the only use of GHRP-2 any regulator has ever authorised

Dissolved in 10 millilitres of saline and injected slowly into a vein on an empty stomach: 100 micrograms for anyone aged 18 or over, and 2 micrograms per kilogram of body weight for children aged 4 to under 18, capped at 100 micrograms for a child over 50 kilograms.

One single injection. Blood is taken before and at 15, 30, 45 and 60 minutes afterwards, and that is the end of it.

Source [01]

Laferrère and colleagues 2005 and 2006 — the appetite studies, in 7 lean healthy men and then in 10 lean and 9 obese people

A drip under the skin at 1 microgram per kilogram of body weight per hour in the first study; 1 or 0.1 micrograms per kilogram per hour against a placebo drip in the second.

270 minutes, followed by a buffet meal.

Source [04]Source [05]

Bowers and colleagues 2004 — the longest exposure ever published in adults, in 17 healthy older men and women

1 microgram per kilogram of body weight per hour, running continuously under the skin.

30 days.

Source [07]

Nijland and colleagues 1998 — the only published study of repeated separate injections in healthy adults, in 9 young men

100 micrograms injected under the skin once a day.

5 days.

Source [06]

Van den Berghe and colleagues 1999 and 2002 — the intensive care studies, in 14 and then 33 critically ill patients

1 microgram per kilogram of body weight per hour into a vein, given alone or alongside a thyroid trigger at the same rate and pulses of a sex-hormone trigger.

5 days, against 5 days of placebo.

Source [03]Source [26]

Mericq and colleagues 1998 and 2003 — the children's treatment studies in Santiago, in 6 and then 10 growth-hormone-deficient children

Under the skin at 0.3, then 1.0, then 3.0 micrograms per kilogram of body weight per day in the first study, with a fourth period adding GHRH. By mouth at 900 micrograms per kilogram twice a day in the second.

Four 2-month periods, 8 months in total; and 12 months.

Source [22]Source [24]

Pihoker and colleagues 1995 and 1997 — the nasal spray studies in short children

For the diagnostic testing, 5 to 20 micrograms per kilogram of body weight into the nose, against 1 microgram per kilogram into a vein. For the treatment study, 5 to 15 micrograms per kilogram into the nose per dose.

Single doses in the diagnostic study; in the treatment study, twice a day for 3 months and then three times a day thereafter — 6 months in 15 children and 18 to 24 months in 6 of them.

Source [09]Source [28]

What people report

• Whether it builds any muscle or adds any strength in a person: never measured, in any study, at any dose, by any route.
• Whether it changes body fat in a person: never measured, even in the 30-day infusion study and the 12-month study in children.
• Whether the appetite effect measured over four and a half hours turns into weight gained over weeks — the only study to follow body weight for a year, in children, found no significant change.
• Whether IGF-1 ever rises on the dosing pattern people actually use: three studies of separate injections or sprays found no change, and only round-the-clock infusion raised it.
• Why intermittent dosing and continuous infusion give opposite IGF-1 answers, and whether more frequent injections would close the gap.
• How far the growth hormone response keeps fading past five days of daily injections, and whether it ever recovers after stopping.
• What happens after 30 days, which is the longest a healthy adult has been given it in any published study.
• What repeated doses do to blood sugar and to how much insulin a person needs — the risk the US regulator named, and one no published study has followed for long enough to see.
• What repeated use does to the stress hormone cortisol and to prolactin, both of which rise after a single dose.
• Whether the immune system makes antibodies against it over time, which the US regulator names as a concern for compounded injections of this peptide.
• Which studies the US regulator meant when it recorded reports of death in critically ill study subjects, infection and pancreatitis — it names none, and says causality has not been established.
• Whether it helps any injury or wound heal, in a person or an animal — nothing has been published either way.
• Whether the faster growth seen in short children in the 1990s would have survived a control group, or how it compares with the growth hormone injections that are the standard treatment.
• What became of the children treated in those studies: none has been followed up in print since 1998.
• Whether it is safe or useful in anyone with diabetes, heart disease or a hormone condition — every published study enrolled healthy volunteers, hospital patients under supervision, or children with growth hormone deficiency.
• Whether there is any difference between men and women, beyond the finding that the acute two-peptide response is larger in older women.
• What the glycine-extended version found in seized vials does in a person: it has never been given to one in a published study.
• How many people have been harmed by it: the US side-effect database holds four reports, all for compounded mixtures rather than GHRP-2 alone, which measures reporting habits rather than safety.
• Whether any of it matters at the amounts sold online: no clinical trial of GHRP-2 is registered on ClinicalTrials.gov under any spelling, so no answer is on its way.

Does GHRP-2 work?

It depends on what you want it to do. At releasing growth hormone, yes, and so reliably that Japan approved it as a medical test: a single injection lifts peak growth hormone to about 85 nanograms per millilitre in a healthy person and leaves it near 1 in someone whose pituitary gland has failed. At making people eat more, yes, and this has been measured against a dummy infusion — people ate about a third more at a buffet. At everything else people buy it for, nobody knows, because muscle, strength and body fat have never been measured in a person taking it, and the one randomised trial that measured whether it slowed the body breaking down its own protein found GHRP-2 alone did no better than placebo.

Source [02]Source [03]Source [05]

Is GHRP-2 FDA approved?

No. There is no approved medicine containing GHRP-2 in the United States — a search of the FDA's own approved-drugs database for pralmorelin or GHRP-2 returns nothing. It is approved in Japan, but only as a diagnostic injection for finding out whether someone can make growth hormone, and Japan's own drug classification files it under agents that are not mainly for therapeutic purposes. In the United States the FDA placed GHRP-2 for injection and nasal spray in the category of compounding substances that raise significant safety risks on 29 September 2023, which is the opposite of an approval.

Source [13]Source [29]Source [30]

Is GHRP-2 legal?

Outside Japan there is no legal way to be prescribed it as a treatment, because it is not approved as one anywhere. In the United States it cannot legally be compounded as an injection or a nasal spray by an outsourcing facility, and on the pharmacy list it sits in the category of substances nominated without adequate support. In Sweden the doping law of 1991 covers, in so many words, chemical substances that increase the production or release of growth hormone — which is exactly what GHRP-2 does — and makes importing, possessing or using them outside medical or scientific purposes a criminal offence.

Source [21]Source [30]Source [31]

What are the side effects of GHRP-2?

For the one approved use — a single injection in a hospital — Japan's product label lists a flush of heat in 16 per cent of people as the commonest, and then low blood pressure, sweating, cold sweat, dry mouth, nausea, stomach discomfort, bloating, hunger, sleepiness, tiredness, unsteadiness, a rise in the liver enzyme ALT and a raised white cell count, each between 0.1 and 5 per cent. There is no placebo figure printed beside any of them. The label also warns that in people with a pituitary tumour, drugs of this kind have been followed by sudden bleeding into the tumour, and it forbids the drug in pregnancy. Nothing on that label describes repeated use, because repeated use has barely been studied.

Source [01]Source [10]

GHRP-2 vs GHRP-6 — what is the difference?

They are close relatives that pull the same lever, and the honest differences are smaller than the marketing suggests. GHRP-2 was built out of GHRP-6 as a stronger version of it, and it is the only one of the family any regulator ever approved — Japan, for a diagnostic test. It is also the one whose appetite effect has actually been measured in people; with GHRP-6 that effect has only ever been shown in rats given it directly into the brain. Where the two are usually said to differ most, they do not: GHRP-2 raises the stress hormone cortisol and the milk hormone prolactin too, about as much as hexarelin does and about as much as a dose of the body's own stress trigger. No published study has ever put GHRP-2 and GHRP-6 side by side in the same people, and neither has ever been tested as a treatment for muscle, fat or healing in a person.

Source [04]Source [20]Source [23]

Does GHRP-2 make you hungry?

Yes, and this is the one claim about the compound that has been properly measured in people. In a double-blind study, 19 lean and obese adults ate 33.5 per cent more at a buffet after a high-dose infusion than after a placebo, and 10.2 per cent more after a low dose — the more they were given, the more they ate. They felt hungrier before the meal, but no less full afterwards, and being obese made no difference. Hunger also appears on the approved Japanese label as a side effect of a single diagnostic injection.

Source [01]Source [04]Source [05]

Does GHRP-2 build muscle?

Nobody has measured it, so there is no evidence either way — and there is a specific reason to doubt it. Growth hormone acts on the body through a second signal called IGF-1, and in every study that gave GHRP-2 as separate doses rather than as a continuous drip, IGF-1 did not rise: not over five days of daily injections in healthy young men, not over eight months of daily injections in children, not over up to two years of nasal spray. The growth hormone burst itself also shrank by about 40 per cent across five days of daily injections. Only a pump running the peptide in around the clock for 30 days raised IGF-1, and even that study never weighed anyone's muscle.

Source [06]Source [07]Source [24]

Can you buy GHRP-2?

It is sold online as a freeze-dried powder labelled for research use only, which is a label rather than a licence. What arrives is a separate question from what is ordered: forensic laboratories in Denmark and Poland analysing seized material found not GHRP-2 but a modified version carrying an extra amino acid on the front, and nobody has studied what that version does in a person. This register does not link to sellers, list prices or print doses to take.

Source [10]Source [19]Source [20]

Is GHRP-2 banned in sport, and can it be tested for?

Yes to both, and there is a twist. The 2026 prohibited list names GHRP-2 by name, with pralmorelin in brackets, under growth hormone releasing peptides in section S2.2.4 — banned at all times, in and out of competition. It is detectable: GHRP-2 and two of its breakdown products showed up in urine for up to about 47 hours after a nasal dose — in one volunteer, which is how many people that study gave each compound to. The twist is that GHRP-2 also hides growth hormone doping — a single injection dragged the test that catches injected growth hormone back down to roughly 40 per cent of the raised reading it should have shown.

Source [11]Source [27]Source [32]

Why is there no sequence shown for GHRP-2?

Because writing one would be a lie. GHRP-2 is six building blocks long, but three of them break the standard code: the first and fifth are mirror-image forms of alanine and phenylalanine, the second is a naphthylalanine that does not occur in nature and has no letter at all, and the chain ends in an amide cap rather than a normal end. Japan's approved label spells the molecule out as D-alanyl-3-(2-naphthyl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide. Any one-letter string would describe a different molecule, so the register prints nothing rather than something that looks right. The US regulator makes the same point when it says GHRP-2 contains an unnatural amino acid that adds to the difficulty of characterising it.

Source [01]Source [12]

1. [01]Approved Japanese package insert for GHRP Kaken 100 for injection (pralmorelin hydrochloride 100 µg), PMDA, revision 3 of July 2025 — approval number 21600AMZ00573; sole indication 'diagnosis of growth hormone secretion deficiency'; contraindicated in pregnancy; adverse reaction table; chemical name and formula C45H55N9O6·2HCl (in Japanese) (2025)
2. [02]Chihara K et al. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. Eur J Endocrinol 2007;157(1):19-27 (77 healthy subjects, 58 patients; peak GH 84.6 ± 60.9 vs 1.36 ± 2.60 µg/L; cut-off 15 µg/L, or 9 with the recombinant standard) (2007)
3. [03]Van den Berghe G et al. The combined administration of GHRP-2, TRH and GnRH to men with prolonged critical illness evokes superior endocrine and metabolic effects compared to treatment with GHRP-2 alone. Clin Endocrinol (Oxf) 2002;56(5):655-69 (33 men randomised across four arms including placebo; GHRP-2 alone did not reduce ureagenesis or raise osteocalcin) (2002)
4. [04]Laferrère B et al. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab 2005;90(2):611-4 (7 lean men, crossover against saline; 32.5 vs 24.2 kcal/kg, p = 0.008) (2005)
5. [05]Laferrère B, Hart AB, Bowers CY. Obese subjects respond to the stimulatory effect of the ghrelin agonist GHRP-2 on food intake. Obesity 2006;14(6):1056-63 (19 people, double-blind randomised; food intake +10.2% at low dose and +33.5% at high dose vs placebo; free full text) (2006)
6. [06]Nijland EA et al. A five day treatment with daily subcutaneous injections of growth hormone-releasing peptide-2 causes response attenuation and does not stimulate insulin-like growth factor-I secretion in healthy young men. Eur J Endocrinol 1998;139(4):395-401 (9 men; peak GH 83 → 59 → 51 µg/L; IGF-I unchanged) (1998)
7. [07]Bowers CY et al. Sustained elevation of pulsatile GH secretion and IGF-I, IGFBP-3 and IGFBP-5 concentrations during 30-day continuous subcutaneous infusion of GHRP-2 in older men and women. J Clin Endocrinol Metab 2004;89(5):2290-300 (17 subjects; the longest published adult exposure; no body composition measured) (2004)
8. [08]Iranmanesh A, Bowers CY, Veldhuis JD. Secretagogue type, sex-steroid milieu and abdominal visceral adiposity individually determine secretagogue-stimulated cortisol secretion. Eur J Endocrinol 2010;163(3):427-34 (42 healthy men, double-blind placebo-controlled; peak cortisol 616 ± 42 nmol/L after GHRP-2 vs grand mean 420 ± 21 after saline, GHRH or somatostatin; free full text) (2010)
9. [09]Pihoker C et al. Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature. J Endocrinol 1997;155(1):79-86 (15 children; height velocity 3.7 → 6.1 cm/year at 6 months, no control group; IGF-1 and IGFBP-3 unchanged) (1997)
10. [10]FDA: Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks — GHRP-2 (for injectable and nasal routes of administration), 503B category 2, added 29 September 2023, naming immunogenicity from aggregation and impurities, an unnatural amino acid, and reports of increased insulin requirement, death of critically ill study subjects, infection and pancreatitis with causality not established (2023)
11. [11]WADA: World Anti-Doping Code International Standard – Prohibited List 2026, section S2.2.4, GH-releasing peptides, naming 'GHRP-2 (pralmorelin)'; S2 prohibited at all times (in force 1 January 2026) (2026)
12. [12]PubChem CID 6918245, pralmorelin (GHRP-2, CAS 158861-67-7) — C45H55N9O6, 818.0 g/mol, IUPAC name showing D-alanine at position 1, D-2-naphthylalanine at position 2, D-phenylalanine at position 5 and a C-terminal amide
13. [13]KEGG DRUG D02040, pralmorelin hydrochloride — Japanese therapeutic category 7223, diagnostic reagents for endocrine function, within class 7 'agents not mainly for therapeutic purpose'; efficacy listed as Diagnostic; target GHSR
14. [14]ClinicalTrials.gov API v2 search for "GHRP-2": totalCount 0. The same query for GHRP2, pralmorelin, KP-102, GPA-748, "GHRP Kaken" and "growth hormone releasing peptide 2" — quoted, as query.term and as query.intr — also returns 0 (checked 3 August 2026 against a control query returning 757 studies for semaglutide)
15. [15]Gondo RG et al. Growth hormone-releasing peptide-2 stimulates GH secretion in GH-deficient patients with mutated GH-releasing hormone receptor (11 patients, 4.5-fold GH rise against 79-fold in 8 controls), J Clin Endocrinol Metab 2001;86(7):3279-83 (2001)
16. [16]Arimura S et al. Assessment of adrenocorticotropic hormone and cortisol responses to growth hormone-releasing peptide-2 in 47 patients, Endocr J 2016;63(6):533-9 — responses were lower in pituitary disease and did not correlate with the CRH test (2016)
17. [17]Kinoshita Y et al. Assessment of adult growth hormone deficiency by the GHRP-2 test: sensitivity 81.3% and specificity 94.5%, against 93.8% for the arginine test, Endocr J 2013;60(2):167-73 (2013)
18. [18]Sigalos JT et al. Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum Insulin-Like Growth Factor-1 Levels, Am J Mens Health 2017;11(6):1752-7 — 105 men screened, 14 included, IGF-1 159.5 to 239.0 ng/mL over a mean 134 days; no body-composition measurement of any kind (2017)
19. [19]Gajda M et al. Seizures after the use of growth hormone secretagogues — analysis of adverse reports, 2018 (2018)
20. [20]Popławska M, Błażewicz A. Determination of peptide hormones in unregulated products, 2018 — the composition of what is actually sold (2018)
21. [21]Lag (1991:1969) om förbud mot vissa dopningsmedel — 1 § point 4 covers chemical substances that increase the production or release of growth hormone; 2 § lists the prohibited acts and 3 § the penalty (1991)
22. [22]Mericq and colleagues, changes in appetite and body weight during long-term oral GHRP-2 in growth hormone deficient children (J Pediatr Endocrinol Metab, 10 children, 12 months, no control group) (2003)
23. [23]Arvat and colleagues, effects of GHRP-2 and hexarelin on GH, prolactin, ACTH and cortisol levels in man, compared with GHRH, TRH and hCRH (Peptides, 6 young and 6 elderly adults) (1997)
24. [24]Mericq and colleagues, effects of eight months treatment with graded doses of GHRP-2 in GH-deficient children (J Clin Endocrinol Metab, 6 children; IGF-I and IGFBP-3 did not increase) (1998)
25. [25]Dominikowski and colleagues, performance-enhancing peptides modulating the GH-IGF1 axis (Front Endocrinol, free full text; places GHRP-2 in a tier defined by having no controlled trials with body-composition endpoints) (2026)
26. [26]Van den Berghe and colleagues, reactivation of pituitary hormone release and metabolic improvement by infusion of GHRP-2 and TRH in protracted critical illness (J Clin Endocrinol Metab, 14 patients, placebo-controlled crossover) (1999)
27. [27]Okano and colleagues, influence of intravenous GHRP-2 on detection of growth hormone doping: growth hormone isoform profiles in Japanese male subjects (Drug Test Anal) (2010)
28. [28]Pihoker and colleagues, diagnostic studies with intravenous and intranasal GHRP-2 in children of short stature (J Clin Endocrinol Metab) (1995)
29. [29]Drugs@FDA via the openFDA API: no approved product matches pralmorelin or GHRP-2 (checked 3 August 2026)
30. [30]FDA: bulk drug substances nominated for use in compounding under section 503B — GHRP-2 (for injectable and nasal routes) in category 2, substances that raise significant safety risks; GHRP-2 for all other routes in category 1 (2025)
31. [31]FDA: bulk drug substances nominated for use in compounding under section 503A, updated 14 May 2026 — GHRP-2 in category 3, nominated without adequate support (2026)
32. [32]Semenistaya and colleagues, determination of GHRP metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, hexarelin and ipamorelin (Drug Test Anal) (2015)