GHRP-2
Growth Hormone Releasing Peptide-2, Pralmorelin, KP-102, GHRP-2 Acetate
The Ground Truth Score
four plain questions, never one numberIt definitely raises GH in humans. Whether that translates to anything useful in healthy adults is still an open question.
Bottom line
GHRP-2 (pralmorelin) is a synthetic hexapeptide ghrelin receptor agonist that reliably stimulates pulsatile GH secretion in humans (confirmed in multiple controlled studies and a Japanese regulatory approval), but evidence for downstream benefits like muscle gain or fat loss in healthy adults is almost entirely extrapolated from animal data and GH-deficient populations. The evidence grade C is pegged to the documented GH-secretion mechanism, not to any human outcome trial for the wellness goals users actually pursue.
Does the science back it?
Do real people feel it?
Is it safe?
Could it be placebo?
Can you legally get it?
Approved abroadA medicine elsewhere, not hereApproved and prescribed as a medicine in other countries, but not by FDA. That is real evidence a regulator somewhere reviewed it, and it is worth weighing. It is not a US route, and it does not mean the version sold to you domestically is that same reviewed product.
Approved in Japan (2004) as a DIAGNOSTIC agent for growth-hormone deficiency, a single-use test, not a therapy anyone is prescribed on an ongoing basis. Not FDA-approved for anything.
Legal status as of 2026-06-16. This is a separate axis from the grades above, and it does not move them. A vote about who may legally prepare a compound is not evidence that the compound works.
"Do real people feel it?" is anecdote, not proof, weighted up because the science is thin, never because it beats a trial. And "could it be placebo?" is not an insult: if you feel better, that's real to you. The point is only to know whether you're paying peptide prices for an expectation.
Why is the evidence this thin? It's mostly economics →
Dose at a glance
full dosing ↓100-300 mcg SubQ, 2-3x daily fasted (no established therapeutic dose; reported protocols only)
Reported, not prescribed. Verify your vial and your math.
The gist
- Reliably spikes GH in humans, confirmed in controlled studies and a Japanese diagnostic approval, but whether that pulse does anything useful for body composition in healthy adults is an open question.
- The cortisol and prolactin co-release are real and documented, not anecdote; that is the key reason ipamorelin exists as a cleaner alternative.
- Almost no one runs it alone. It is nearly always stacked with a GHRH analog, which makes it impossible to know what GHRP-2 is actually contributing to any outcome you see.
First documented human use
1997. Arvat et al. published a controlled human comparison study (intravenous, dose-response) documenting GH, prolactin, ACTH, and cortisol elevation in 12 healthy men (6 young, 6 elderly). PMID 9285939.
The pitch
What people claim it does
Stated plainly and neutrally, exactly as you'll hear it. We grade each one below.
- Amplifies natural GH pulses without suppressing endogenous production
- Stacked with CJC-1295 or GHRH for synergistic GH release
- Supports lean mass and fat loss via GH-driven lipolysis
- Improves sleep quality through GH pulsatility
- Anti-inflammatory effects in tissue repair
The data behind each bullet
What actually backs it
GHRP-2 significantly increases GH secretion in healthy humans
Controlled human studies show dose-dependent IV GH release. The primary citation is a single n=12 (6 young, 6 elderly) IV pharmacodynamic study (Arvat 1997, PMID 9285939). Additional human data comes from a Van den Berghe 2002 critical-illness infusion study (n=33, PMID 12030918) and a continuous-infusion appetite study (n=7, PMID 15699539). Approved in Japan (2004) as a diagnostic agent for GH deficiency based on this mechanism (reviewed in Drugs R&D 2004, PMID 15230633; primary Japanese trial data is in the regulatory submission and is not publicly accessible as a standalone English PubMed record). The B grade applies to the GH-secretion mechanism claim only, not to any downstream wellness outcome.
Arvat et al. 1997 (PubMed 9285939) - GH, prolactin, ACTH, cortisol in 12 men (6 young, 6 elderly); IV bolus only ↗GHRP-2 increases appetite and food intake
Small RCT in 7 healthy lean men showed 36% increase in caloric intake during subcutaneous GHRP-2 infusion vs saline. Effect attributed to ghrelin receptor agonism in hypothalamus. Well-controlled but very small sample. Note: this study used continuous subcutaneous infusion, not the bolus injection used by community protocols.
Laferrere et al. 2005 (PMC2824650, PMID 15699539) - food intake in 7 healthy men; continuous infusion protocol ↗GHRP-2 improves muscle protein deposition and growth performance
Animal data only. Study in growth-retarded yaks showed enhanced myofiber diameter and protein synthesis pathway activation. No equivalent controlled trial exists in healthy adult humans.
Zhang et al. 2016 (PMC4760683) - yak muscle deposition study; animal model only ↗GHRP-2 has anti-inflammatory effects in tissue
In vitro human granulosa cell study showed attenuation of PKC-induced inflammation. Not a clinical outcome study. Mechanism is plausible but extrapolating to therapeutic use in vivo is speculative.
Ji et al. 2016 (PMC5000754) - granulosa cell inflammation; in vitro human cell study, not a clinical trial ↗GHRP-2 elevates cortisol and prolactin alongside GH
Consistent finding across human studies. GHRP-2 activates ACTH/cortisol pathways at levels comparable to hCRH and raises prolactin (lower than TRH). Documented in the Arvat 1997 pharmacodynamic study and corroborated by the Van den Berghe 2002 critical illness study. This is a documented side-effect mechanism, not a claimed benefit.
Arvat et al. 1997 (PubMed 9285939) - ACTH/cortisol/prolactin in men; corroborated by Van den Berghe 2002 (PMID 12030918) ↗Prove it
Can you tell if it's working?
The honest test: if it's working, is there any objective way to see it — a blood marker, a scan, a wearable? For a lot of peptides the answer is no, and that's worth knowing before you spend on labs or gear.
Blood IGF-1 is the only honest efficacy signal for GHRP-2; no non-blood modality (DEXA body comp, wearable sleep) survives as an objective efficacy tracker.
Bloodwork
A routine lab actually tracks whether this is working.
GHRP-2 is a ghrelin/GHS-R1a agonist that stimulates endogenous pituitary GH release; sustained GH elevation drives hepatic IGF-1 production, and IGF-1 is a routine, integrated serum marker of GH action, so an efficacy signal does appear in standard LabCorp/Quest bloodwork.
IGF-1 rises versus the patient's own baseline, shifting toward the upper part of the age/sex reference range. Expect a within-range increase, not the supraphysiologic levels seen with injected rhGH.
GHRP-2 drives pituitary GH secretion via the ghrelin receptor; GH induces hepatic IGF-1, the standard integrated readout of GH action in humans (Bowers 2004 showed a sustained IGF-1 plateau on 30-day continuous GHRP-2).
Small upward move that tracks IGF-1; more stable day-to-day than GH and useful as a corroborating signal rather than a primary one.
IGFBP-3 is GH-dependent and co-regulated with IGF-1; it rose alongside IGF-1 during sustained GHRP-2 exposure (Bowers 2004), so it supports but does not independently prove the IGF-1 result.
Draw baseline
Before first dose; morning venous draw. IGF-1 and IGFBP-3 do not require fasting.
Retest
4-8 weeks on stable, adequate dosing (IGF-1 plateaus within ~2 weeks of consistent exposure).
Read this before you spend on labs
IGF-1 is the honest proof that the GH axis is actually being driven, which is exactly what a secretagogue is supposed to do. Two caveats keep this from being a slam dunk: (1) Delivery matters. Continuous/adequate exposure raises IGF-1 to a plateau (Bowers 2004), but 5 days of low-dose daily SC bolus injections in healthy young men caused tachyphylaxis and did NOT move IGF-1 (PMID 9820615). A flat IGF-1 at 4-8 weeks may mean the dose/schedule isn't sustaining the axis, not that GHRP-2 is inert. (2) GHRP-2 also raises cortisol, ACTH, and prolactin via off-target ghrelin-receptor activity; those are NOT efficacy markers and should not be read as \"it's working.\" IGF-1 also does not measure the appetite, sleep, recovery, or body-composition effects people actually chase, only that GH is being secreted downstream.
- Bowers et al. 2004, JCEM — 30-day continuous SC GHRP-2 sustains GH, IGF-1, IGFBP-3 in older men and women ↗
- Sigalos et al. 2017, Am J Mens Health — GH secretagogue treatment raises serum IGF-1 in hypogonadal men ↗
- Bowers & Granda-Ayala 2001, Endocrine — GH/IGF-1 response to acute and chronic GHRP-2 and GHRH in older adults ↗
- Nijland et al. 1998, Eur J Endocrinol — 5-day daily SC GHRP-2 causes response attenuation and does not stimulate IGF-1 in young men ↗
Bottom line
Blood IGF-1 (handled separately, tier=direct) is the only honest way to confirm GHRP-2 is pharmacologically active, and even that shows modest within-range increases. Beyond blood, nothing survives as an efficacy tracker. DEXA lean/fat mass is mechanistic hope, not human-demonstrated for GHRP-2: the body-composition benefit in healthy adults is Grade D extrapolation, the peptide is almost never run without a GHRH analog (so attribution is impossible), and any real effect would fall below single-scan measurement noise — a channel that can't distinguish signal from noise or from the stack isn't a tracker. Wearable sleep is non-informative to negative: GH is coupled to slow-wave sleep physiologically, but the human GHRP-2 evidence does not support a device-detectable SWS gain, so it cannot verify efficacy. The most reproducible human effect is increased appetite/food intake (~36%, Grade B) plus a cortisol/prolactin rise — none cleanly captured by a consumer device, and none the outcome users are chasing. A CGM would likely show glucose drifting up (GH secretagogues reduce insulin sensitivity), but that is a safety/harm signal, not proof the peptide is 'working,' so it is not an efficacy channel. Net: verify with blood IGF-1; treat everything else as unverifiable for efficacy.
Logging baseline vs retest is the whole game. The Truth Tracker is our free log for bloodwork, DEXA, genetics, and wearable data — bring your own numbers.
How to track it →Mechanism
How it's assumed to work
Assumed · theoretical pathway
ASSUMED (based on receptor pharmacology confirmed in human cells and clinical GH secretion data, not direct mechanistic proof in vivo). GHRP-2 binds the ghrelin receptor (GHSR-1a) in pituitary somatotrophs, triggering calcium influx and protein kinase C activation, which stimulates GH exocytosis. Simultaneously activates hypothalamic GH-releasing pathways and suppresses somatostatin (the GH brake). Also activates ghrelin receptors in the hypothalamus to stimulate appetite via NPY/AgRP neurons. The cortisol/ACTH elevation reflects additional binding at corticotrophs.
Dosing & handling
What users and clinicians report
100-300 mcg subcutaneous injection, 2-3x daily, typically pre-workout and before sleep. Taken fasted or with low-carb context to avoid blunting GH pulse. Clinical diagnostic dose is a single 1-2 mcg/kg IV bolus. Note: human pharmacodynamic studies used IV bolus or continuous infusion, not subcutaneous bolus; community protocols extrapolate the route.
These are community-reported protocols, not prescribed doses. The biggest dosing risk is the cortisol/prolactin elevation, which is dose-dependent and worsens with frequency. There is no established therapeutic dose for healthy adults. Vial concentrations vary widely across research chemical suppliers.
Timing & food
Taken fasted or at least 30-60 minutes away from carbohydrates and fats, as insulin blunts GHRP-2-stimulated GH release. Common injection windows: upon waking (fasted), pre-workout, and before sleep (last meal 2-3 hours prior).
Half-life
Approximately 15-30 minutes plasma half-life (GH peak at 30-60 min post-subcutaneous injection). GH response returns to baseline within 90-120 minutes. Some sources report longer half-life (up to 2.5 hours in animal models). Short enough that timing relative to meals and training matters meaningfully.
Reconstitution sensitivity
Moderate. Reconstitute with bacteriostatic water. Keep refrigerated after reconstitution (stable approximately 30 days at 2-8C). Avoid repeated freeze-thaw. Exposure to elevated temperatures degrades the peptide.
Real-world signal
What people actually report
Anecdote, not proof, weighted because the science is thin. Here's the record, graded on volume, consistency, and how credible the sources are.
Volume
High volume of community use and forum discussion, particularly in bodybuilding and anti-aging communities. One of the most discussed GH secretagogues alongside CJC-1295.
Consistency
Reports are fairly consistent on the GH-pulse feel (flushing, hunger, heaviness post-injection) but body composition outcomes are inconsistent and heavily confounded by stacking.
Source credibility
Lower than volume suggests. Most reports are from stacked protocols. The GH pulse is real, but attributing specific body changes to GHRP-2 vs co-administered compounds is nearly impossible from community data.
- Anecdote: users consistently report a pronounced hunger spike 30-45 minutes after injection, sometimes described as uncomfortable. This matches the controlled study finding of 36% increased caloric intake.
- Anecdote: post-injection flushing and a warm/heavy sensation are frequently described, particularly at higher doses. Attributed to the GH pulse and transient cortisol bump.
- Anecdote: some users report improved sleep depth when dosed pre-bed, though this is not separated from the GH-during-sleep effect that occurs naturally or from co-administered CJC-1295.
- Anecdote: long-term users on community forums note plateau effects over weeks, consistent with GH secretagogue receptor desensitization, leading many to cycle it (e.g., 5 days on / 2 days off).
Placebo risk, Moderate
GH release itself is objective and measurable, and the short-term acute effects (hunger, flushing, lethargy post-injection) are pharmacologically real. However, downstream claims like muscle gain, sleep quality, and fat loss are subjective and heavily confounded by lifestyle, training, diet, and co-administered compounds. The gap between confirmed GH pulse and attributed wellness outcomes is where placebo risk is highest.
Risk panel
What could go wrong
Adverse events
Consistently documented in human studies: cortisol and prolactin elevation (both transient, occur at standard doses), increased hunger/appetite, water retention, flushing, and transient drowsiness. The cortisol signal is notably stronger than ipamorelin. Cortisol and prolactin bumps are real signals from multiple controlled studies (Arvat 1997 PMID 9285939; Van den Berghe 2002 PMID 12030918), not anecdote.
Theoretical concerns
Chronic GH elevation carries theoretical risks including insulin resistance, fluid retention, and potential stimulation of latent neoplastic growth (GH is a growth factor). No long-term human safety data exists in healthy adults. Elevated prolactin with chronic use could cause gynecomastia or libido effects.
Contraindications
Active cancer or family history of GH-responsive tumors. Diabetes or pre-diabetes (GH raises blood glucose acutely). Pregnancy or breastfeeding. History of pituitary adenoma.
Honest unknowns
Long-term effects of repeated pulsatile GH stimulation in healthy adults are completely unstudied. The primary human pharmacodynamic data is from IV bolus and continuous infusion protocols, not the subcutaneous bolus injection used by community protocols. Receptor desensitization kinetics with chronic dosing are not well characterized in humans. Interaction with TRT, GLP-1 agonists, and other peptide stacks has not been studied.
Confound watch
Almost universally stacked with GHRH analogs (CJC-1295 with or without DAC, modified GRF 1-29), which dramatically amplifies GH response and makes attribution impossible. Frequently co-administered with TRT, which independently improves body composition. Community users rarely run GHRP-2 alone. GLP-1 base effects (if on tirzepatide/semaglutide) suppress appetite, which directly opposes GHRP-2's orexigenic mechanism.
History
Discovery → first use → status
- 1980sGHRP-2 developed by Cyril Bowers and colleagues as part of a series of synthetic GH secretagogues based on enkephalin analogs.
- 1997Arvat et al. publish a controlled human dose-response comparison of GHRP-2 and hexarelin vs GHRH in 12 men (6 young, 6 elderly), establishing that GHRPs elicit stronger GH responses than GHRH alone at equivalent IV doses (PMID 9285939).
- 2002Van den Berghe et al. publish a 5-day randomized study of GHRP-2 alone vs GHRP-2 combined with TRH and GnRH in 33 critically ill men, documenting GH and cortisol elevation and metabolic effects (PMID 12030918).
- 2004Pralmorelin (GHRP-2) approved in Japan by PMDA as a diagnostic agent for GH deficiency testing, marketed by Kaken Pharmaceutical. The pivotal Japanese trial data resides in the regulatory submission; a 2004 Drugs R&D review article (PMID 15230633) summarizes the development history and approval. This is the first and only regulatory approval for any GH secretagogue worldwide.
- 2010s-presentGHRP-2 becomes popular in research and bodybuilding communities as an unscheduled peptide. No FDA approval for any indication. Sold as research chemical in the US.
Verification
The COA standard, applied
Compiled from the cited sources below. Where no completed human trial exists, the grade says so.
The full verification standard →Sources
Where this comes from
- Arvat et al. 1997 - Effects of GHRP-2 and Hexarelin on GH, prolactin, ACTH and cortisol in man (PubMed 9285939). n=12 (6 young, 6 elderly). IV bolus only. ↗· Core human comparative pharmacodynamic study. Single n=12 IV dose-response. Confirmed GH release plus cortisol/prolactin elevation. Route limitation: IV bolus, not subcutaneous.
- Laferrere et al. 2005 - GHRP-2 increases food intake in healthy men (PMC2824650, PMID 15699539). n=7, continuous subcutaneous infusion. ↗· Small but controlled crossover study in lean men. 36% caloric intake increase vs saline. Real human appetite signal. Used continuous infusion, not bolus injection.
- Van den Berghe et al. 2002 - Combined GHRP-2, TRH and GnRH in critically ill men (PubMed 12030918). n=33 critically ill men. ↗· 5-day randomized study in critically ill patients, not healthy adults. Corroborates GH and cortisol elevation signal. Not a wellness or body composition study.
- Drugs R&D 2004 review of pralmorelin development and Japanese approval (PubMed 15230633). Review article, not a primary trial. ↗· Authoritative review summarizing pralmorelin clinical development history and PMDA approval. The underlying Japanese pivotal trial data is in the regulatory submission, not publicly available as a standalone English PubMed record.
- Zhang et al. 2016 - GHRP-2 and cysteamine in yaks with growth retardation (PMC4760683). Animal model. ↗· Animal model for muscle protein deposition claims. Often cited as if it proves human muscle benefit. It does not.
- Ji et al. 2016 - GHRP-2 attenuation of inflammation in human ovarian granulosa cells (PMC5000754). In vitro cell study. ↗· In vitro human cell study. Anti-inflammatory mechanism is plausible but this is not a clinical outcome study.
The four lenses reflect the evidence and the real-world record as of the last review and will change as data arrives. Real-world signal and reported feedback are anecdote, not proof. Nothing here is medical advice or a prescription.