GHRP-2 and GHRP-6: The Older GH Peptides - Hunger Effect, Dosage, Better Alternatives

Key takeaways

GHRP-2 (pralmorelin) and GHRP-6 are synthetic six-amino-acid growth hormone-releasing peptides from the 1980s and 1990s. Both activate the ghrelin receptor, the same target as ipamorelin and hexarelin. Neither is growth hormone, and neither has ever been approved in the United States.
Both release a large, short pulse of growth hormone (GH). GHRP-6 at 1 mcg/kg intravenously raised peak GH about 57-fold over placebo in healthy men. IGF-1 rose with continuous infusions but not with the intermittent dosing people use, and a 48-week placebo-controlled GHRP-2 trial in 126 children found no effect on growth or IGF-1.
The hunger effect is real and measured for GHRP-2: a 270-minute infusion made healthy men eat 36% more at a buffet. GHRP-6 is reputed to be hungrier still, but no human trial has measured its effect on food intake. Both also raise cortisol, ACTH and prolactin.
Seller charts (GHRP-6 100 to 300 mcg, GHRP-2 100 to 150 mcg, two or three times a day) sit in the range of the studied single doses. No study has shown that this schedule builds muscle, burns fat or improves recovery.
No US pharmacy may compound either peptide in October 2026. Both are in Category 3 for 503A pharmacies and on the Category 2 safety list for outsourcing facilities. The better options are sermorelin, which a licensed pharmacy can dispense, or a real workup for growth hormone deficiency.

GHRP-2 and GHRP-6 at a glance

Also called: pralmorelin (GHRP-2), KP-102 (GHRP-2), GPA-748 (GHRP-2), growth hormone releasing peptide-6, His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 (GHRP-6)
Class: Synthetic growth hormone-releasing peptides (GHRPs): six-amino-acid ghrelin-receptor (GHS-R1a) agonists from the 1980s and 1990s
Route: Studied intravenously, under the skin, in the nose and by mouth; sold as research vials for injection under the skin
FDA status: Never FDA-approved. Category 3 for 503A compounding (nominated without enough information to evaluate) and Category 2 under FDA's 503B interim policy since September 29, 2023. Not legally compoundable as of October 2026.
FDA Category 2 (compounding restricted): No
Available by prescription (US): No legal US source: Category 3 for 503A pharmacies and Category 2 for 503B outsourcing facilities; sold only as research-use vials
Best-studied use: Hormone studies in healthy adults, older adults and children; GH-deficiency diagnostic testing (GHRP-2 in Japan); appetite studies (GHRP-2)
Typical monthly cost (telehealth, 2026): No legitimate price, because no legal product exists; the prescribable secretagogue, sermorelin, runs $150 to $400 a month

What GHRP-2 and GHRP-6 are and how they work

GHRP-6 came first. It is the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, designed by Cyril Bowers's group at Tulane before anyone knew which natural hormone it imitated. Its first dose-response study in people, in 18 healthy men, appeared in 1990 (Bowers 1990). GHRP-2, later given the international name pralmorelin, is a second-generation six-amino-acid peptide from the same research line. It never reached the US market; in Japan it became a diagnostic agent for growth hormone deficiency (Chihara 2007) (Dominikowski 2026). If peptides are new to you, start with what peptides are.

The natural hormone they imitate turned out to be ghrelin, a 28-amino-acid hormone made mostly in the stomach, found in 1999. Ghrelin does two things at once: it releases GH from the pituitary and it makes people hungry. GHRP-2 and GHRP-6 act on ghrelin's receptor, GHS-R1a, so they do both as well. Four features follow from that.

They need the GHRH system. The receptor is a separate pathway from growth hormone-releasing hormone (GHRH), the target of sermorelin and tesamorelin. Low doses of GHRP-6 and GHRH together released GH synergistically, far more than either alone (Bowers 1990). That synergy is the logic behind the GHRH-plus-GHRP "stacks", including CJC-1295 with ipamorelin.
The pulse is short. GH peaks within about an hour of a dose and is gone within a few hours; in the 1992 study GHRP-6 left the blood with a half-life of about 20 minutes (Bowers 1992).
They are not selective. Both raise ACTH and cortisol, and at higher doses prolactin, along with GH (Bowers 1990) (Raun 1998). That is the problem ipamorelin was designed to fix.
They work by mouth, poorly. Oral GHRP-6 released GH, but a 300 mcg/kg oral dose did what 1 mcg/kg did intravenously, about 0.3% of the activity (Bowers 1992).

What the evidence shows

GHRP-2 and GHRP-6 have more human data than almost any peptide sold as a research chemical: dozens of studies from university endocrinology groups. Nearly all of them measured hormones for a few hours. Here is how the marketed claims hold up.

GHRP-2 and GHRP-6 claims, graded by the evidence behind them
Claim	Grade	What the evidence shows	Sources
Releases growth hormone in healthy adults	A	In 18 healthy men, GHRP-6 at 0.1, 0.3 and 1 mcg/kg intravenously raised mean peak GH to 7.6, 16.5 and 68.7 mcg/L versus 1.2 on placebo. In 77 healthy Japanese adults, a 100 mcg intravenous GHRP-2 dose produced a mean peak of 84.6 mcg/L within 60 minutes.	Bowers 1990; Chihara 2007
Diagnoses growth hormone deficiency	A	The one accepted medical use. In 58 adults with severe GH deficiency confirmed by insulin tolerance testing, the peak GH after 100 mcg GHRP-2 was 1.36 mcg/L against 84.6 in healthy subjects; a cut-off of 15 mcg/L separated the groups, with good reproducibility.	Chihara 2007
Increases hunger and food intake	B	For GHRP-2, yes: 7 lean men infused at 1 mcg/kg per hour for 270 minutes ate 35.9% more at a buffet, every one of them more than on saline. In 19 lean and obese adults the effect was dose-dependent: 10.2% at 0.1 and 33.5% at 1 mcg/kg per hour. For GHRP-6 no human food-intake trial was found.	Laferrère 2005; Laferrère 2006
Raises IGF-1	B	Only with continuous exposure. A 34-hour GHRP-6 infusion raised IGF-1 from 252 to 312 mcg/L in 9 young men, and a 30-day GHRP-2 infusion under the skin raised it to a stable plateau in 17 older adults. Intermittent injections did not: see the next row.	Jaffe 1993; Bowers 2004
Promotes growth in short children	B	No, in the largest trial. 126 GH-deficient children randomized to placebo or nasal GHRP-2 twice daily for 48 weeks showed no difference in growth or IGF-1. Smaller uncontrolled studies had reported modest gains; the authors concluded the GH pulses were too brief.	Tanaka 2014
Raises only growth hormone	B	No. GHRP-6 at 1 mcg/kg raised prolactin and cortisol about 2-fold in men; four 50 mcg doses at night raised ACTH and more than doubled cortisol in the first half of the night. In pigs, GHRP-2 and GHRP-6 both raised ACTH and cortisol.	Bowers 1990; Frieboes 1995; Raun 1998
Improves sleep	C	Mixed. In healthy men, four night-time GHRP-6 doses increased light stage 2 sleep by about 25 minutes but did not change deep slow-wave sleep, while cortisol rose.	Frieboes 1995
Builds muscle or burns fat	D	Never tested as an outcome in adults. A 2026 review of self-administered GH-axis peptides found no controlled efficacy trials for GHRP-6 or GHRP-2 in body composition.	Dominikowski 2026
Helps recovery from critical illness	C	In 33 men with prolonged critical illness, a 5-day GHRP-2 infusion reactivated GH and normalized IGF-1, but only the combination with TRH and GnRH reduced protein breakdown. It never became a treatment.	Van den Berghe 2002

A = strong human trials or meta-analyses · B = small or short human trials · C = observational, mechanistic or indirect human data · D = animal/in-vitro only, or no evidence. Grades describe the evidence, not whether we recommend the use.

Three things stand out.

The GH pulse is not the problem. These peptides reliably release GH, which is why Japan uses GHRP-2 as a test (Chihara 2007). What they have not done with intermittent dosing is turn the pulse into a sustained rise in IGF-1, the hormone that carries most of GH's effects on tissue. The clearest test of that, 48 weeks of twice-daily dosing in 126 children against placebo, found nothing (Tanaka 2014).

The hunger is a feature of the receptor. GHRP-2 increased food intake in lean and obese adults alike, and the effect grew with the dose (Laferrère 2006). For someone trying to lose fat, that works against the goal. For someone underweight it might help, which is the direction researchers took.

The side hormones come along. Cortisol and prolactin rise at the doses that release the most GH (Bowers 1990). Ipamorelin, developed by Novo Nordisk, was selected because it did not raise cortisol in pigs while GHRP-2 and GHRP-6 did (Raun 1998); our GHRP-2 vs ipamorelin article covers that trade in detail.

What you are promised versus what is documented

Seller and forum pages describe GHRP-6 as the "hunger peptide" for bulking and GHRP-2 as the stronger, cleaner option, and list lean muscle, fat loss, recovery, joint repair, better sleep and anti-aging. The evidence sorts those into four bins.

Documented in humans: a large, short GH pulse after injection, nasal or oral dosing; more hunger and more food eaten (GHRP-2); rises in ACTH, cortisol and prolactin; a usable diagnostic test for GH deficiency (GHRP-2).
Documented only with continuous infusion: higher IGF-1 over days to a month (Jaffe 1993) (Bowers 2004). Nobody takes these peptides by pump.
Tested and not found: faster growth or higher IGF-1 with twice-daily nasal GHRP-2 for 48 weeks; deeper sleep with GHRP-6.
Never tested in humans: muscle or strength gains, fat loss, recovery, tendon or joint healing, longevity.

"Cleaner" also deserves a correction. GHRP-2 is more potent than GHRP-6 per dose in pigs, but it raised ACTH and cortisol there too (Raun 1998).

GHRP-2 and GHRP-6 vs the alternatives

	GHRP-2	GHRP-6	Ipamorelin	Hexarelin	Sermorelin
What it is	Six-amino-acid GHRP (pralmorelin)	Six-amino-acid GHRP, the original	Five-amino-acid GHRP	Six-amino-acid GHRP	GHRH(1-29); acts on the GHRH receptor
GH release in humans	Mean peak 84.6 mcg/L after 100 mcg IV	Peak 68.7 mcg/L at 1 mcg/kg IV	One pulse per dose in 40 men	Near-maximal at 1 to 2 mcg/kg IV	GH up at 1 to 2 mg a day
Hunger	Measured: about 34 to 36% more food	Reputed; not measured in a human trial	Not measured in humans	Not a prominent effect in studies	Not a known effect
Cortisol and prolactin	Rise	Rise	Not raised in pigs; not measured in people at clinic doses	Rise	Not a known effect
FDA status, October 2026	Never approved in the US; Category 3 (503A), Category 2 (503B)	Same as GHRP-2	Never approved; committee voted against in 2024; Category 2 (503B)	Never approved; in no FDA category	Formerly approved (Geref); compoundable
Typical monthly cost	No legitimate price	No legitimate price	No legitimate price	No legitimate price	$150 to $400 (cost guide)

The hexarelin profile and the HGH peptides guide cover the rest of the class. The practical point is the last two rows: of the five, only sermorelin can be prescribed and filled by a licensed pharmacy.

Dosage: what was studied versus what sellers circulate

Study	Peptide, dose and route	People	Result
Bowers 1990	GHRP-6 0.1, 0.3, 1 mcg/kg IV, single doses (7 to 70 mcg at 70 kg)	18 healthy men	Dose-dependent GH; prolactin and cortisol up about 2-fold at 1 mcg/kg
Bowers 1992	GHRP-6 100 and 300 mcg/kg by mouth (7 and 21 mg at 70 kg)	5 men; 9 short children	GH up; oral activity about 0.3% of IV
Frieboes 1995	GHRP-6 50 mcg IV four times during one night	Healthy men	More stage 2 sleep; ACTH and cortisol up
Chihara 2007	GHRP-2 100 mcg IV, single dose	77 healthy adults, 58 GH-deficient adults	The diagnostic test; healthy peak 84.6 vs 1.36 mcg/L
Laferrère 2005 and 2006	GHRP-2 0.1 or 1 mcg/kg per hour under the skin for 270 minutes (about 30 or 315 mcg in total at 70 kg)	7 lean men; 19 lean and obese adults	Food intake up 10% and 34 to 36%
Bowers 2004	GHRP-2 1 mcg/kg per hour by continuous pump under the skin for 30 days	17 healthy older adults	GH and IGF-1 up; safety screens normal
Tanaka 2014	GHRP-2 nasal 50 to 200 mcg twice daily by weight band, 48 weeks	126 GH-deficient children	No difference from placebo in growth or IGF-1
Seller and forum charts	GHRP-6 100 to 300 mcg, GHRP-2 100 to 150 mcg, under the skin, two or three times a day, fasted, '8 to 12 weeks'	Self-experimenters	No controlled data on this schedule

The seller figures come from a supplement-seller guide summarized in a 2026 review of self-administered GH-axis peptides (Dominikowski 2026). A 100 mcg injection is close to the GHRP-2 diagnostic dose and to 1.4 mcg/kg of GHRP-6 for a 70 kg adult, so a single seller dose will release GH. The open question is what two or three short pulses a day accomplish. The only long, controlled test of repeated GHRP-2 dosing found no change in IGF-1 or growth (Tanaka 2014), and the studies that did raise IGF-1 used round-the-clock infusions.

The "fasted" instruction has a basis: food and insulin blunt GH release, which is why the diagnostic tests are done after an overnight fast (Chihara 2007). It also means the injection lands when hunger is already high. The GHRP-6 dosage article covers every studied GHRP-6 dose and the hunger effect in more detail.

We give no reconstitution example or units table for GHRP-2 or GHRP-6, because there is no legal product to reconstitute: every vial for sale is a research product of unverified content. Our reconstitution calculator is built for medications a pharmacy has dispensed with a labeled concentration.

Side effects and who should not use them

What the studies recorded. Hunger and larger meals with GHRP-2 (Laferrère 2005); rises in ACTH, cortisol and prolactin (Bowers 1990) (Frieboes 1995). In 10 GH-deficient children taking oral GHRP-2 twice daily for a year, 7 reported a clear increase in appetite during the first six months, and body mass index did not change significantly (Mericq 2003). The published studies were short and small, which is not enough to find uncommon or long-term harms.

What FDA flagged. When FDA put both peptides on its Category 2 list for outsourcing facilities in 2023, it cited for GHRP-2 immunogenicity and reports of serious adverse events, including deaths among critically ill study subjects and pancreatitis, without established causality, and for GHRP-6 possible effects on cortisol and blood glucose, as our Category 2 explainer records (FDA Category 2 page). The critically ill patients were people in intensive care, the population of the Leuven infusion studies (Van den Berghe 2002), not healthy users. The flag says the safety record is incomplete; it does not say the peptide killed anyone.

What users report. A 2026 review lists prolactin and cortisol rises, appetite changes, blood sugar disturbances, fluid retention, muscle and joint aches and injection-site reactions across self-administered GH-axis peptides, and singles out GHRP-2 and GHRP-6 as the most strongly appetite-stimulating (Dominikowski 2026).

Do not use GHRP-2 or GHRP-6, and do not let anyone sell them to you, if you have:

an active cancer or a recent cancer history (GH and IGF-1 are growth signals);
diabetes, prediabetes or a strong family history of either;
an eating disorder, or you are trying to lose weight (the hunger effect works against you);
a pituitary or adrenal disorder, including a prolactinoma or Cushing's syndrome, or you take medication that affects cortisol or prolactin;
pregnancy or breastfeeding.

Athletes subject to testing should treat both as prohibited: WADA lists growth hormone-releasing peptides in class S2, as our peptides and steroids explainer sets out. For the broader picture, see peptide side effects.

Legal status in the United States

Our legal tracker explains the tests a bulk ingredient must pass before a pharmacy may compound it. GHRP-2 and GHRP-6 fail them as follows, as of October 2026.

Never FDA-approved. Neither peptide is a component of any US-approved drug. GHRP-2's diagnostic role in Japan does not carry over.
Category 3 for 503A pharmacies. FDA lists both as nominated without enough information to evaluate (FDA categories 2026). Category 3 is outside FDA's interim policy, so a 503A pharmacy has no basis to compound them.
Category 2 for 503B outsourcing facilities. On September 29, 2023, FDA added GHRP-2 (injectable and nasal) and GHRP-6 to the 503B Category 2 list of substances that may present significant safety risks, alongside ipamorelin (FDA Category 2 page).
The biologics rule does not apply, because both are six amino acids long. It does not need to.

So no state-licensed pharmacy and no outsourcing facility may legally compound GHRP-2 or GHRP-6, and a prescription cannot change that. They were not among the peptides FDA took off Category 2 in April 2026, and they were not on the July 2026 advisory committee agenda. A vial labeled "research use only" is not a workaround: FDA's 2026 warning letters treated research-labeled peptides sold with dosing information as unapproved drugs for human use, as the tracker documents.

Cost and the better alternatives

There is no legitimate price for GHRP-2 or GHRP-6, because there is no legitimate product. Anything sold under these names in the United States in 2026 is a research vial or a clinic reselling one.

The better alternative depends on what you want.

A clinician-supervised rise in GH: sermorelin, a GHRH analog with an FDA approval history that a licensed pharmacy can compound, at roughly $150 to $400 a month through telehealth (peptide therapy cost). It does not stimulate hunger or cortisol.
Measured excess belly fat: tesamorelin, brand Egrifta only, at about $2,400 to $2,800 a month; as a biological product it cannot be compounded.
Symptoms that might be GH deficiency: an endocrinologist and a stimulation test. In Japan that test may itself be GHRP-2; in the US it is usually macimorelin, glucagon or insulin. A diagnosis opens the door to approved growth hormone, which a peptide vial does not.
Appetite and weight gain in illness: this is the use GHRP research pointed toward, and it belongs with a physician, not a research vial.

Our complete guide to peptide therapy walks through the evaluation, labs and monitoring a legitimate prescription involves, and our comparison of online clinics shows what each provider offers. If a clinic lists GHRP-2 or GHRP-6 on its menu, ask which pharmacy makes it and under what authority.

Older adults and women

Older adults were studied, and they respond. In the 30-day infusion study, healthy older men and women kept a raised GH output and IGF-1 throughout, with normal safety screens, and the GHRP-2 plus GHRH synergy was 2.3-fold larger in older women than in older men (Bowers 2004). That is a physiology result under continuous pump delivery, not a treatment, and no study measured strength, falls or any aging outcome.

The GHRP-2 diagnostic test was unaffected by sex and slightly lower in older and heavier adults (Chihara 2007). We found no study of either peptide in menopause. Neither should be used in pregnancy or while breastfeeding.

Bottom line

GHRP-2 and GHRP-6 are the first generation of ghrelin-mimicking peptides: reliable GH releasers that also make you hungry and raise cortisol and prolactin. GHRP-2 earned a real medical job as a diagnostic test in Japan. As treatments, both stalled for the same reason: short pulses from intermittent dosing did not raise IGF-1 or change growth in the trial that tested it properly, and the hunger came with the hormone.

They also have no legal path to a patient in the United States. If you want a GH secretagogue under medical supervision, the one a licensed pharmacy can dispense is sermorelin. If you suspect real GH deficiency, get tested. If you want GHRP-6 for the appetite, know that what you can buy is an unlabeled research vial.

Frequently asked questions

+What is growth hormone releasing peptide-2 used for?

In medicine, mainly as a diagnostic test: in Japan, a single 100 mcg intravenous dose of GHRP-2 (pralmorelin) is used to check whether an adult's pituitary can release growth hormone. It was also tested in the 1990s and 2000s for short stature in children and for prolonged critical illness, and did not become a treatment for either. It has never been approved in the United States. Online it is sold as a research chemical for muscle, fat loss and recovery, none of which a human trial has shown.

+What is the difference between GHRP-2 and GHRP-6?

Both are six-amino-acid peptides that activate the ghrelin receptor and release growth hormone. GHRP-6 is the original, studied in people from 1990; GHRP-2 came later and is more potent per dose in animals. GHRP-2 is the one with measured hunger data in humans: a 270-minute infusion made healthy men eat about 36 percent more at a buffet. Both raise cortisol and prolactin, and both are in the same legal position in the US: neither may be compounded.

+Does GHRP-6 make you hungry?

Probably, but the human evidence is borrowed. Ghrelin itself increased food intake by about 28 percent in healthy volunteers, and GHRP-2, which acts on the same receptor, increased it by about 34 to 36 percent. GHRP-6 stimulated eating in rats, and users report strong hunger. We found no human trial that measured food intake after GHRP-6, so the size of its hunger effect in people is not documented.

+What are the downsides of taking GHRP-2 or GHRP-6?

The documented ones are hunger, rises in cortisol, ACTH and prolactin, and a growth hormone pulse that is short and does not reliably raise IGF-1. FDA lists GHRP-2 as a possible safety risk, citing immunogenicity and serious adverse events, including deaths among critically ill study subjects and pancreatitis, without established causality; for GHRP-6 it cites possible effects on cortisol and blood glucose. Long-term safety has never been studied, and research vials have unknown content and sterility.

+Is GHRP-2 legal in the US?

Owning it is not a crime, but no licensed US pharmacy may make it. GHRP-2 and GHRP-6 are not FDA-approved, are not on the list of bulk substances pharmacies may use, sit in Category 3 for 503A pharmacies, and are in Category 2, the safety-risk list, for 503B outsourcing facilities. Vials sold as research chemicals are unapproved drugs when marketed for human use, and a prescription does not change that.

+Does GHRP-2 raise IGF-1?

Sometimes. A 30-day continuous infusion under the skin in healthy older adults raised IGF-1 to a stable plateau, and a 34-hour GHRP-6 infusion raised it in young men. But eight months of daily GHRP-2 injections in GH-deficient children, and 48 weeks of a twice-daily nasal spray in 126 GH-deficient children, did not raise IGF-1. Short pulses from occasional injections appear to be too brief.

+What is the best growth hormone releasing peptide?

By evidence and legality, sermorelin, which is not a GHRP but a GHRH analog: it has an FDA approval history, human trials and can be compounded on prescription. Tesamorelin has the strongest trial data but is brand-only Egrifta and only makes sense for measured visceral fat. Among the ghrelin-receptor peptides, ipamorelin was designed to avoid the cortisol and hunger effects of GHRP-2 and GHRP-6, but it cannot be legally compounded either.

+Is GHRP-6 banned in sports?

Yes. The World Anti-Doping Agency lists growth hormone-releasing peptides, including GHRP-2 and GHRP-6, among the growth hormone releasing factors in class S2, prohibited at all times, and anti-doping laboratories test for them in urine.