GHRP-2 (pralmorelin): what it is, the research, dosage and side effects

GHRP-2 is a member of the growth hormone-releasing peptide family that began with GHRP-6 and also includes hexarelin and ipamorelin. Its generic drug name is pralmorelin. In the 1990s it was developed as a possible treatment for short stature in children, including an oral version tested by Wyeth-Ayerst under the code GPA-748 ^[1].

It found its lasting role in diagnosis instead. Japan’s KEGG drug database lists pralmorelin hydrochloride, brand name GHRP, as a Japanese-approved diagnostic reagent for endocrine function ^[2], and Japanese endocrinologists use the “GHRP-2 test” to check for adult growth hormone deficiency ^[3][4].

Its sequence is D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2 ^[30]. GHRP-2 came out of a series of small GH-releasing peptides made by Cyril Bowers’s group at Tulane University and the German company Polygen. Kaken acquired the rights and sublicensed them to Wyeth for the US and Canada; a US phase 2 programme for GH deficiency appears to have been discontinued, while in Japan Kaken took it forward as a diagnostic agent and ran phase 2 trials for short stature ^[25]. In early human work, GHRP-6, GHRP-1 and GHRP-2 were progressively more effective GH releasers, all released more GH than GHRH, and all worked by mouth ^[12].

Outside Japan, the GHRP-2 peptide is used only in research. The name GHRP-2 acetate, often seen on research products, refers to the peptide as an acetate salt; the Japanese diagnostic product is the hydrochloride salt ^[2]. Both are the same active peptide, sometimes also written GHRP2.

GHRP-2 activates the ghrelin receptor (GHS-R1a) on the pituitary and hypothalamus, producing a rapid pulse of GH. In pigs, GHRP-2 was more potent than ipamorelin or GHRP-6 but produced a smaller maximum GH response, and unlike ipamorelin it raised ACTH and cortisol ^[5]. In people, the GHRP-2 test also releases ACTH, and a 2022 study argued that measuring ACTH during the test helps pick up adrenal insufficiency that often accompanies GH deficiency. Of 36 patients with hypothalamic or pituitary disorders in that study, 17 had secondary adrenal insufficiency, and 16 of those 17 also had severe GH deficiency; the ACTH response to GHRP-2 screened for pituitary-related adrenal insufficiency with 83% sensitivity and 88% specificity ^[4].

Like ghrelin, GHRP-2 increases appetite. In a controlled study, seven lean healthy men given a subcutaneous infusion of GHRP-2 ate about 36% more at a buffet meal than on a saline day, and every participant ate more ^[6]. Because it acts on a different receptor from GHRH, GHRP-2 is often paired with GHRH analogues such as CJC-1295; that combination has not been studied in published trials.

The strongest data concern diagnosis. In a Japanese validation study of 77 healthy people and 58 patients with GH deficiency confirmed by insulin tolerance testing, a single 100 µg intravenous dose of GHRP-2 produced a mean peak GH of 84.6 µg/L in healthy subjects and 1.36 µg/L in patients. A cut-off of 15 µg/L corresponded to the standard insulin tolerance test threshold, and repeat tests were reproducible ^[3].

Treatment studies were small. A phase 1 study in ten children with short stature measured the pharmacokinetics of a single 1 µg/kg intravenous dose: GHRP-2 had a half-life of about half an hour and produced a predictable GH rise ^[7]. In ten prepubertal children with GH deficiency (average age about 10, and well below average height) given oral GHRP-2 (900 µg/kg twice daily) for a year, seven reported increased appetite in the first six months, but BMI did not change significantly ^[1].

Animal work has recently extended into tissue healing. In a rat model of rotator cuff tear, GHRP-2 reduced inflammatory (M1) macrophages at the repair site and improved histology, bone density and biomechanical strength of the tendon-bone interface at eight weeks ^[8]. This is a single animal study, and it has not been tested in people.

Two further Japanese studies tested the diagnostic cut-offs. In 71 adults with pituitary tumours who had all three tests, the GHRP-2 test identified severe adult GH deficiency with a sensitivity of 81.3% and a specificity of 94.5% against the insulin tolerance test ^[26]. In 65 older patients, a lower peak GH cut-off of 8.08 ng/mL was proposed, reflecting the smaller response with age ^[27].

The most detailed treatment studies were in critical illness. In Belgian intensive care patients with prolonged critical illness, a continuous infusion of GHRP-2 raised GH secretion four- to six-fold and IGF-1 by 61% within 24 hours, without changing cortisol ^[19]. When GHRP-2 was combined with TRH for five days, markers of bone formation and leptin rose and protein breakdown fell ^[20]. A randomised comparison in 33 men found that GHRP-2 alone restored GH and IGF-1 but did not reduce urea production, a marker of muscle breakdown; only the combinations with TRH, or with TRH and GnRH, did. GHRP-2 alone and with TRH also raised lactate and white cell count by day 5 ^[21].

Heart research is limited to one animal study. Rabbits pretreated with GHRP-2 under the skin at 160 µg/kg a day for 14 days recovered normal diastolic function after a brief interruption of coronary blood flow in isolated hearts, while those pretreated with recombinant GH did not. GHRP-2 raised IGF-1 by only 8% in these animals ^[28]. The heart research on hexarelin is more extensive.

Most searches for GHRP-2 benefits are about muscle, fat loss, recovery and sleep. The research does not test those outcomes in healthy adults. What it does show is a reliable acute GH release, which is why GHRP-2 works as a diagnostic test ^[3]; faster growth in some short children ^[16][17]; restoration of GH and IGF-1 in prolonged critical illness ^[19]; and higher food intake ^[6][23].

In healthy young men, five days of daily GHRP-2 injections did not raise IGF-1, though osteocalcin, a marker of bone formation, rose ^[15]. The only study in men seeking body-composition changes was a retrospective chart review: 14 men on testosterone who took GHRP-2, GHRP-6 and sermorelin together had a rise in average IGF-1 from 159.5 to 239.0 ng/mL, but lean mass and fat were not reported as outcomes and there was no control group ^[24]. No study shows that GHRP-2 builds muscle or reduces fat in adults.

The appetite effect is dose-related. In lean and obese adults, a low infusion raised food intake by about 10% and a higher one by about 34%, with no difference between the two groups ^[23]. For people trying to lose weight that is a drawback, and it is one of the more consistent GHRP-2 findings in humans.

GHRP2 results in the studies are measured in hormone levels and, in children, height. A single dose raises GH within minutes, and GHRP-2 has a half-life of about half an hour ^[7]. With daily injections the response fades. In nine healthy men given 100 µg under the skin once a day, the average GH peak fell from 83 µg/L on day 1 to 59 on day 3 and 51 on day 5, although GH was still released ^[15].

Longer studies were in children. Six prepubertal children with GH deficiency received GHRP-2 injections at increasing doses over six months, then with GHRH for two more; overnight GH rose with dose, but the effect of each injection was brief, IGF-1 did not rise, and growth velocity was higher on treatment than before or after, with no side effects observed ^[16]. In 15 short children using a nasal spray two to three times a day, height velocity rose from 3.7 to 6.1 cm a year at six months and was maintained in the six children followed for 18 to 24 months ^[17].

Searches for GHRP-2 before and after photos find user posts, not research. No published study reports adult body-composition results for GHRP-2, so there is no evidence-based before-and-after timeline.

GHRP-2 and GHRP-6 act on the same receptor. In rat pituitary cells, GHRP-2 worked through the same receptor and mechanism as GHRP-6 despite their different structures; each desensitised the cells to the other, and giving both at maximal concentrations released no more GH than either alone ^[13]. Both acted synergistically with GHRH. Our GHRP-2 vs GHRP-6 comparison sets the two side by side.

The difference between GHRP-2 and 6 is mainly strength. In the first human studies, GHRP-2 was more effective than GHRP-6 ^[12]. In pigs, GHRP-2 was more potent, and both raised ACTH and cortisol ^[5]. In rats, about half of a nasal dose of GHRP-2 was absorbed, while nasal absorption of GHRP-6 was somewhat lower ^[14]. GHRP-2 is also the one that went on to a diagnostic approval in Japan ^[2]. Our GHRP-6 guide covers its own studies.

Taking GHRP-2 and GHRP-6 together is common in online protocols. The rat-cell data suggest little added GH at high doses because they compete for the same receptor ^[13]. The only human data on the pairing come from the retrospective review above, which added sermorelin and could not separate the effect of each peptide ^[24].

Both are ghrelin-receptor agonists. In pigs, GHRP-2 was more potent than ipamorelin but produced a smaller maximum GH response, and it raised ACTH and cortisol while ipamorelin did not ^[5]. In rats, nasal absorption was about 50% for GHRP-2 and about 20% for ipamorelin ^[14]. GHRP-2 has more human data, including its diagnostic use and paediatric studies. They have not been compared directly in people.

Sermorelin, CJC-1295 and tesamorelin are GHRH analogues, so GHRP-2 vs sermorelin is a comparison of two receptors. In one study GHRP-2 released more GH than GHRH(1-29), the sequence of sermorelin, though synergy between them was not shown in that study ^[22]. In children tested with both, GHRP-2 and GHRH together gave a synergistic response ^[18]. Sermorelin was a licensed US medicine until its manufacturer discontinued it; the FDA later found it was not withdrawn for safety or effectiveness reasons ^[35].

GHRP-2 vs CJC-1295 is a contrast in duration. GHRP-2 is cleared in about half an hour ^[7]. CJC-1295 with DAC had a half-life of about six to eight days in healthy adults and kept GH and IGF-1 raised for six days or more after one injection ^[36]. GHRP-2 vs tesamorelin is a contrast in status: tesamorelin is an approved medicine for excess abdominal fat in adults with HIV ^[34], while GHRP-2 is approved only as a single-dose diagnostic in Japan.

Blends sold as CJC-1295 & GHRP-2, Mod GRF 1-29 & GHRP-2, or a CJC-1295 ipamorelin GHRP-2 blend combine a GHRH analogue with one or two ghrelin-receptor agonists. The logic comes from GHRH studies. In critically ill patients, adding GHRH to a GHRP-2 infusion doubled GH release again and raised IGF-1 by a further 40% ^[19], and the paediatric study added GHRH for its final two months ^[16].

None of those studies used CJC-1295 or Mod GRF 1-29, and no published study has tested any of these blends. Adding ipamorelin to GHRP-2 puts two agonists on the same receptor, which the rat-cell data suggest adds little at high doses ^[13]. Blends that also include tesamorelin or MGF have no published data. Dosage charts for blends, and the 10 mg blend vials sold online, are not based on research on the combination. Prices for CJC-1295 and GHRP-2 are listed separately on our site.

Sermorelin and GHRP-2, sometimes with GHRP-6, is the one combination with any human record, the uncontrolled chart review of 14 men described above ^[24]. GHRP-2 with TRH and GnRH was tested in critically ill men as a hospital treatment, not as a supplement stack ^[21].

GHRP-2 has been given intravenously, under the skin, by nasal spray and by mouth in human studies. The GHRP-2 nasal spray studies were in children: 15 µg/kg intranasally produced a mean peak GH of 31.3 µg/L as a test ^[18], and nasal doses of 5 to 15 µg/kg two to three times a day were used for treatment ^[17]. The oral study used 900 µg/kg twice daily, a much larger dose than by injection ^[1].

Research products are sold as GHRP-2 powder, a freeze-dried solid for mixing with water, usually in 5 mg or 10 mg vials. Nasal sprays sold online have not been tested against the paediatric studies. After nasal use, GHRP-2 metabolites could be detected in urine for up to 47 hours ^[29].

The Japanese diagnostic test uses a single 100 µg intravenous dose after an overnight fast ^[3]. Other human studies used a single 1 µg/kg intravenous dose in children ^[7], an infusion of 1 µg/kg per hour under the skin for 270 minutes in the appetite study ^[6], and 900 µg/kg by mouth twice daily in the paediatric oral study ^[1]. These are the doses reported in the studies, not recommendations. For laboratory reconstitution arithmetic, see our peptide calculator.

Treatment studies used 100 µg under the skin once daily for five days in healthy men ^[15], 0.3 to 3 µg/kg a day under the skin in children with GH deficiency ^[16], 5 to 15 µg/kg by nasal spray two to three times daily in children ^[17], and continuous infusions in critically ill adults ^[19]. The retrospective review reported 100 mcg of each of three peptides three times daily as prescribed by a clinic, not as a tested regimen ^[24]. Rabbits received 160 µg/kg a day ^[28]. None of these is a GHRP-2 dosage per day for anyone outside a study, and animal doses are not converted to human ones.

As arithmetic only: a 10 mg vial mixed with 2 mL of water holds 5 mg per mL, which is 50 µg per unit on a U-100 insulin syringe; a 5 mg vial in 2 mL holds half that. The calculator works as a GHRP-2 dosage calculator for any vial size and volume, and our bacteriostatic water guide covers the diluent.

In the published studies the effects are mainly hormonal: GH, ACTH and cortisol rise acutely ^[4][5], and appetite increases ^[1][6]. Its long use as a single-dose diagnostic in Japan does not tell us about repeated or long-term dosing, for which there are no adequate safety data. A 2026 clinical review lists prolactin and cortisol elevations, appetite changes, altered glucose and fluid retention among the adverse effects reported with GH secretagogues as a class ^[9].

GHRP-2 side effects in individual studies follow the same pattern. Food intake rose by up to about a third ^[23]. The paediatric injection study reported no side effects or toxicity over eight months ^[16], and the nasal spray was well tolerated in children ^[17]. In critically ill men, GHRP-2 alone raised blood lactate and white cell count by day 5 ^[21]. No study has followed adults using GHRP-2 for months, and research-grade products carry the added risks of wrong content and contamination; see our guide to third-party testing.

Pralmorelin is approved in Japan as a diagnostic agent only ^[2]. We found no approval in the UK, US, Canada, Australia or New Zealand. It is named on the WADA Prohibited List as GHRP-2 (pralmorelin) under section S2 and is banned at all times ^[10]. Anti-doping laboratories have identified glycine-extended GHRP-2 analogues in seized and black-market products ^[11]. For national rules on buying research peptides, see our legal status overview.

In the US, GHRP-2 is on the FDA’s Category 2 list of bulk drug substances that may present significant safety risks in compounding, as of 22 April 2026 ^[31]. In Australia, pralmorelin is a Schedule 4 prescription-only substance and is also listed in Appendix D of the Poisons Standard, so possession requires authority ^[32]; see Australia legal status. New Zealand classifies GHRPs as prescription medicines ^[33]. In the UK, GHRP-2 is not listed under the Misuse of Drugs Act, but selling or supplying an unauthorised medicinal product is prohibited under the Human Medicines Regulations.

Research-grade GHRP-2 is sold as freeze-dried powder. No stability data have been published for these products; see our guides to storing peptides and bacteriostatic water.

Compare prices per milligram, check the certificate of analysis with our guide on how to read a COA, and prefer third-party tested suppliers.

Anyone looking to buy GHRP-2 is buying a research chemical, not a licensed medicine. Prices are listed by market, including GHRP-2 prices in the UK and in Australia. Our methodology explains how suppliers are rated, and our guide to research peptides explains what the label means. A GHRP-2 UK listing is subject to the same rules on supply as anywhere else in the country.