Pinc PeptideThe girly peptide research blog

GHRP-2 (pralmorelin) · Dose evidence · updated 8 October 2026

GHRP-2 dosage: what studies actually used

The short answer

No GHRP-2 dose is established for muscle gain, fat loss or any other treatment, and we found no trial of those uses67. As of 7 October 2026, Japan approves it only as a one-time test for growth hormone (GH) deficiency, given into a vein: 100 µg for adults and 2 µg/kg for ages 4 to 17 (100 µg above 50 kg)8. Research doses ranged from single test doses and hours-long infusions to nasal sprays and doses by mouth, often set per kilogram of body weight, and they mostly measured hormones, appetite or growth9101112. This page reports those doses and is not dosing advice.

Not dosing advice. This page reports doses that studies and approved labels used, with their sources. It does not recommend a dose, and we do not give mixing, injection or unit-conversion instructions. Gray-market vials often do not contain what their label says. How we report doses.

Every dose studied in people

StudyWhoPeopleDose and routeWhat happened
Kaken (maker) post-marketing survey, 2006 to 2012, from Japan’s 2014 regulatory re-examination Children and adults tested for GH deficiency at 19 sites in Japan 503 One test dose in routine use; the report does not list the doses given
Into a vein · One test		 No side effects were recorded in the 503 patients, unlike in the trials before approval; the company said one reason was that people in the trials were monitored more closely13. Judged against doctors’ diagnoses made with at least two other tests, the GHRP-2 test had a sensitivity of 0.853 for severe GH deficiency (the share of severe cases it caught) and a specificity of 0.885 (the share of other patients it correctly cleared), in 502 patients13.
Chihara 2007, diagnostic validation study Healthy adults, and adults whose GH peaked below 3 µg/L on the insulin tolerance test, the standard first test for GH deficiency 135 100 µg once, after an overnight fast
Into a vein · One test; blood sampled for 2 hours		 GH peaked within 60 minutes in everyone, averaging 84.6 µg/L in the 77 healthy adults and 1.36 µg/L in the 58 patients9. A cut-off of 15 µg/L (9 µg/L when GH is measured against the recombinant WHO standard) corresponded to the insulin test’s 3 µg/L9.
Tanaka 2014, double-blind, placebo-controlled trial Short children with GH deficiency, before puberty 126 Under 20 kg: 50 or 100 µg; 20 kg or more: 100 or 200 µg; or placebo; twice a day
Nasal spray · 48 weeks		 Height SD scores, a measure of height against children of the same age, changed by 0.07 on placebo, 0.03 on the low dose and 0.02 on the high dose, with no significant difference, and IGF-1, a blood marker of GH action, did not differ significantly among the groups11. The authors concluded that ‘growth cannot be promoted by a transient increase in endogenous GH secretion’11.
Kaken confirmatory trial (phase III), 2004 application summary Patients diagnosed with complete GH deficiency, in Japan 50 100 µg or 2.0 µg/kg once, compared with the insulin tolerance test
Into a vein · One test		 Results agreed with the insulin test in 37 of 42 patients (88.1%), and GH peaked at a median of 15 minutes, against 45 minutes after insulin14. Side effects followed GHRP-2 in 23 of 50, mainly stomach rumbling and a feeling of warmth, all mild, and followed the insulin test in 32 of 50, mainly symptoms of low blood sugar, serious in 214.
Kaken dose-finding study in children, 2004 application summary Children being assessed for short stature, in Japan 38 0.5, 1.0 or 2.0 µg/kg once
Into a vein · One test		 GH did not rise in a straight line with dose, but the 2.0 µg/kg group stood out14. Side effects occurred in 6 of 38, mainly a feeling of warmth and sweating, all mild and brief14.
Van den Berghe 2002, randomized study Men with prolonged critical illness 33 1 µg/kg per hour alone (9 men), with TRH (a hormone that switches on the thyroid) 1 µg/kg per hour, or with TRH plus GnRH (a hormone that drives testosterone) 0.1 µg/kg every 90 minutes; or placebo
Infusion (route not stated in the abstract) · 5 days		 GHRP-2 alone restarted GH release and brought IGF-1 back to normal, but it did not reduce urea production, a sign of protein breakdown; the combinations with TRH did15. On day 5, blood lactate and white-cell counts were higher with GHRP-2 alone or with TRH15.
Van den Berghe 1997, randomized crossover study Critically ill adults, average age 63 26 1 µg/kg, then 1 µg/kg per hour, alone or with GHRH (growth hormone-releasing hormone); or placebo
Infusion (route not stated in the abstract) · 21 hours		 GHRP-2 raised average GH 4- to 6-fold and IGF-1 by 61% within 24 hours, without changing the patients’ high cortisol levels16.
Laferrère 2006, double-blind, randomized study Healthy, weight-stable people: 10 lean, 9 obese 19 0.1 or 1 µg/kg per hour, or placebo
Infusion under the skin · 270 minutes, on each of three visits		 People ate 10.2% more at a buffet lunch on the low dose and 33.5% more on the high dose than on placebo, whether lean or obese, and GH rose with dose in everyone10.
Drug-level study described on the Japanese label Healthy men 18 0.3, 1.0 or 3.0 µg/kg once
Into a vein · Single dose		 Plasma levels 5 minutes after the dose were 4.25, 12.45 and 34.20 ng/mL, and the label notes that the approved adult dose is 100 µg8. Kaken’s phase I study of the same three doses in healthy men reported only stomach rumbling, 4 times at 3.0 µg/kg, all mild14.
Pihoker 1997 Short children, half with GH deficiency and half with short stature of unknown cause 15 5 to 15 µg/kg twice a day for 3 months, then three times a day
Nasal spray · 6 months (6 children for 18 to 24 months)		 Growth speed rose from 3.7 cm a year to 6.1 cm at 6 months and was 6.0 cm at 18 to 24 months, while IGF-1 did not change significantly; the authors called the spray well tolerated17.
Sigalos 2017, chart review Men on testosterone, average age 33.2, seeking more lean mass and less fat; 14 of 105 met the inclusion criteria 14 100 µg each of GHRP-2, GHRP-6 and sermorelin, three times a day
Injection under the skin · Average 134 days		 IGF-1 rose from 159.5 to 239.0 ng/mL6. The full text gives the route and says body measurements were not available for most of the men at follow-up, which the authors say limited what the study could show about body mass index and lean mass1.
Arvat 1997, comparison with hexarelin Healthy young adults aged 22 to 27 (6) and healthy older adults aged 66 to 73 (6) 12 1 and 2 µg/kg once each (older adults: 2 µg/kg), compared with GHRH 1 µg/kg
Into a vein · Single tests		 In young adults, 1 µg/kg gave a strong GH response, higher than GHRH, and 2 µg/kg gave a higher response than 1 µg/kg18. Prolactin, another pituitary hormone, and ACTH and cortisol, two stress hormones, rose too, so the effect is not specific to GH18.
Mericq 2003 Children with GH deficiency, before puberty 10 900 µg/kg twice a day
By mouth · 12 months		 Seven of the 10 reported a significant increase in appetite in the first 6 months, but the rise in body mass index scores, from 0.21 to 0.25, was not statistically significant12.
Bowers 2001 Older men and women with low GH output and low IGF-1 10 Test doses of 1 µg/kg and 10 µg/kg; then 1 µg/kg per hour
Tests into a vein and under the skin; then infusion under the skin · Single tests, then 30 days		 The 10 µg/kg dose under the skin gave a GH response about twice as high as 1 µg/kg19. During the 30-day infusion, GH pulses and IGF-1 rose within 24 hours and stayed higher for the 30 days19.
Pihoker 1998, phase I drug-level study Short children before puberty (9 boys, 1 girl), average age 7.7 10 1 µg/kg once
Into a vein · One dose; blood sampled for 2 hours		 GH rose predictably and significantly, to an average peak of 50.7 ng/mL20.
Nijland 1998 Healthy young men 9 100 µg once a day
Injection under the skin · 5 days		 GH was still released each day, but peak GH fell from 83 µg/L on day 1 to 59 on day 3 and 51 on day 5, a significant weakening of the response2. IGF-1 did not rise, though osteocalcin, another blood marker of GH action, rose from 3.2 to 4.2 µg/L2.
Laferrère 2005 Lean, healthy men 7 1 µg/kg per hour, or saline as a placebo
Infusion under the skin · 270 minutes		 The men ate 35.9% more at a buffet-style meal with GHRP-2 than with saline, and every one of them ate more21.
Moreno-Reyes 1998, sleep study in random order Healthy young men 7 1 µg/kg once, or saline as a placebo
Into a vein · Single dose late in the night		 Each dose was followed by a GH pulse and a brief rise in prolactin, but sleep did not change, and deep (slow-wave) sleep in particular did not increase3.
Mericq 1998 Children with GH deficiency, before puberty 6 0.3, then 1.0, then 3.0 µg/kg a day; then 3 µg/kg with GHRH 3 µg/kg
Injection under the skin · Four 2-month periods		 Overnight GH rose with dose, but the effect of each injection was brief, and IGF-1 did not rise22. Growth was faster during treatment than before or after it, and no side effects were seen22.
Haruta 2015, case report A 38-year-old woman with a 20-year history of anorexia nervosa 1 100 µg four times a day in week 1; then 200 µg before each meal and 100 µg before sleep
Nasal spray · About 1 year		 Her weight rose from 21.1 kg to 27.8 kg over 14 months, fatigue and muscle strength improved, and no obvious side effects were seen4. The authors saw no added benefit for her low blood sugar when the dose went from 100 to 200 µg5.
Kaken dose-finding study in adults (phase II), 2004 application summary Healthy adult men (number not given in the summary) – 25, 50 or 100 µg, given twice about 4 weeks apart
Into a vein · Two single doses		 GH peaks and totals rose with dose and were about the same after the second dose as after the first14. Side effects, mainly stomach rumbling, warmth and sweating, were mostly mild and not linked to dose14.
Thomas 2011, anti-doping excretion study Urine samples from an excretion study (number of people not given) – 10 mg once
By mouth · Single dose		 A known breakdown product of GHRP-2 was detectable in urine for over 20 hours, while the intact drug was not found23.

Studies, animals and users: kept apart

Doses below are what studies used or what a label says. They are not advice, and gray-market products may not contain what their label says.

In human studies

Japan’s approved test dose is 2 µg/kg for ages 4 to 17 (100 µg above 50 kg) and 100 µg for adults, injected slowly into a vein while fasting8. Studies in adults used 100 µg IV once for diagnosis9; 0.1 or 1 µg/kg per hour as a 270-minute infusion under the skin for appetite1021; a 1 µg/kg bolus then 1 µg/kg per hour for 21 hours, or 1 µg/kg per hour for 5 days, in critically ill patients1516; and 1 µg/kg per hour under the skin for 30 days in older adults19. Studies in children used a nasal spray of 50 to 200 µg twice daily for 48 weeks11, nasal doses of 5 to 15 µg/kg two or three times a day17, 0.3 to 3 µg/kg per day under the skin22 and 900 µg/kg by mouth twice daily for 12 months12. An anti-doping study gave one 10 mg oral dose23. These studies measured hormones, appetite, growth or detection, not muscle or fat7.

In animal studies

Pigs: single IV doses of 2 to 100 µg/kg raised GH in proportion to dose, and 30 µg/kg under the skin once daily for 30 days raised daily weight gain by 22% and feed efficiency by 21%, with a partly weaker GH response by day 1024. Rats and dogs: IV doses released GH in proportion to dose8.

What users report Anecdotal · not validated · not a recommendation

A 2026 medical review compiled bodybuilding-forum reports: 100 to 150 µg under the skin, 2 or 3 times a day7.

Half-life and how it is taken

Half-life
About 25 to 41 minutes (0.42 to 0.69 hours) after a dose into a vein in healthy men8Elimination half-life after single IV doses of 0.3, 1.0 or 3.0 µg/kg in 18 healthy men. No metabolites were found in plasma after a 100 µg IV dose; by 24 hours about 2% of the dose appeared unchanged in urine and about 4% as metabolites, and excretion is thought to be mainly through bile, as in rats and dogs8. In 10 children given 1 µg/kg IV, the half-life was 0.55 hours and GH peaked at about 25 minutes (0.42 hours)20.
Routes
  • Intravenous injection (the approved one-dose test in Japan, and hospital studies)
  • Injection or infusion under the skin (research studies; the usual gray-market route)
  • Nasal spray (tested in children for growth)
  • By mouth (tested in children and in an anti-doping study)

Japan’s approved test dose

GHRP-2 is approved in Japan as GHRP KAKEN100 Injection (pralmorelin), a prescription product whose only approved use is diagnosing GH deficiency; the label we read on 7 October 2026 was revised in July 20258. Japan approved it on 22 October 2004, and Japan’s drug regulator reported that, as of 4 February 2014, it was not approved or sold in any other country13. As of 7 October 2026, Drugs@FDA lists no US product containing it2526.

The dose is given once, into a vein, with the patient fasting and at rest, because food, stress and exercise can change GH levels; blood is drawn before the dose and 15, 30, 45 and 60 minutes after it8.

A GH peak of 15 ng/mL or less (9 ng/mL when GH is measured against the recombinant standard) points to severe GH deficiency; if the peak is higher but other findings still suggest it, the label says to consider another stimulation test8. No trials were done in children under 4, and it must not be given to anyone who is or may be pregnant8.

Kaken chose the label doses because they gave the largest GH release in its dose-finding studies: 100 µg among 25, 50 and 100 µg in healthy men, and 2.0 µg/kg among 0.5, 1.0 and 2.0 µg/kg in children14. Among side effects, the label lists a feeling of warmth, at a rate of 16.0%, along with stomach rumbling and sweating8.

This is a one-time diagnostic dose, not a treatment dose: the label’s only use is diagnosing GH deficiency, and it sets no repeated or treatment schedule8.

What repeated doses did

Two single doses given about 4 weeks apart produced about the same GH response14. Daily or nonstop dosing gave mixed results:

  • Daily injections: in 9 healthy men given 100 µg under the skin once a day, GH peaks shrank over 5 days and IGF-1 did not rise2.
  • Nonstop infusion: in 10 older adults given 1 µg/kg per hour under the skin, GH pulses and IGF-1 stayed higher for 30 days19.
  • Critical illness: in men given 1 µg/kg per hour for 5 days, IGF-1 returned to normal, but protein breakdown fell only when TRH was added15.
  • Children with GH deficiency: daily injections for 8 months raised GH only briefly after each dose and did not raise IGF-122, and a twice-daily nasal spray for 48 weeks did no better than placebo for growth11.

What the studies measured, and what it is promoted for

A 2026 medical review describes peptides that act on the GH system, GHRP-2 among them, as used off-label for physique and performance, and promoted for recovery, fat loss and muscle building7. Claim by claim:

  • Muscle and fat: we found no trial. The only study we found of people using it for that goal measured IGF-1, and body measurements were missing for most of the men16.
  • Appetite and weight: infusions made healthy people eat more at one meal, and children taking it by mouth for a year reported more appetite without a significant change in body mass index101221. One woman with anorexia nervosa gained weight on a nasal spray4.
  • Growth in children: two small studies reported faster growth during treatment, but the one placebo-controlled trial, in 126 children, found no benefit111722.
  • Sleep: in the one sleep study we found, 1 µg/kg into a vein late in the night did not change sleep3.
  • Recovery and healing: we found no study of exercise recovery or wound healing in people. The closest are two studies in critically ill patients, which measured hormones and markers of protein breakdown over 21 hours or 5 days1516.

Why a gray-market dose is uncertain

As of 7 October 2026, Finnrick, a service that publishes lab results for peptide samples, listed no GHRP-2 tests, so no independent data show how much GHRP-2 gray-market vials hold27. FDA recall records name GHRP-2 in 30 compounded sermorelin products, recalled by 9 US pharmacies between 21 May 2012 and 12 September 2019 for lack of sterility assurance28. A vial may also hold a look-alike: doping-control chemists found glycine-extended GHRP-2, which carries an extra amino acid, in products seized by Danish customs29.

Questions people ask

How much GHRP-2 should I take?

No dose is established for muscle gain, fat loss or any other treatment, and we found no trial of those uses67. The only approved dose we found is Japan’s one-time diagnostic test, 100 µg into a vein for adults, which is not a treatment dose8. GHRP-2 is not approved in the US, and by our reading US pharmacies may not compound it2530313233.

Is GHRP-2 dosed by body weight?

Japan’s label uses 2 µg/kg for ages 4 to 17 (100 µg above 50 kg) and a fixed 100 µg for adults8. Research studies often set doses per kilogram too, from 1 µg/kg into a vein to 900 µg/kg by mouth twice a day in children1220.

Has GHRP-2 been tested for muscle growth or fat loss?

We found no such trial67. The closest is a chart review of 14 men on testosterone who used it with GHRP-6 and sermorelin; it measured IGF-1, and body measurements were missing for most of the men16.

How long have people taken GHRP-2 in studies?

In the studies on this page, the longest courses were 12 months by mouth in 10 children and 18 to 24 months of nasal spray in 6 children1217. In adults, the longest were about a year of nasal spray in one woman with anorexia nervosa and an average of 134 days in the chart review46.

Does GHRP-2 help you sleep?

We found one sleep study: in 7 young men, 1 µg/kg into a vein late in the night was followed by a GH pulse but did not change sleep or increase deep sleep3.

Go deeper

Sources

  1. 1Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum Insulin-Like Growth Factor-1 Levels (full text) American Journal of Men’s Health, Nov 2017. pmc.ncbi.nlm.nih.gov
  2. 2A 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 European Journal of Endocrinology, Oct 1998. pubmed.ncbi.nlm.nih.gov
  3. 3Evidence against a role for the growth hormone-releasing peptide axis in human slow-wave sleep regulation American Journal of Physiology, May 1998. pubmed.ncbi.nlm.nih.gov
  4. 4One-year intranasal application of growth hormone releasing peptide-2 improves body weight and hypoglycemia in a severely emaciated anorexia nervosa patient Journal of Cachexia, Sarcopenia and Muscle, Sep 2015. pubmed.ncbi.nlm.nih.gov
  5. 5One-year intranasal application of growth hormone releasing peptide-2 improves body weight and hypoglycemia in a severely emaciated anorexia nervosa patient (full text) Journal of Cachexia, Sarcopenia and Muscle, Sep 2015. pmc.ncbi.nlm.nih.gov
  6. 6Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum Insulin-Like Growth Factor-1 Levels American Journal of Men’s Health, Nov 2017. pubmed.ncbi.nlm.nih.gov
  7. 7The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration Frontiers in Endocrinology, 18 Jun 2026. frontiersin.org
  8. 8GHRP KAKEN100 Injection (注射用GHRP科研100): package insert, revised July 2025 (in Japanese) KEGG MEDICUS (JAPIC package insert data), Jul 2025. kegg.jp
  9. 9A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency European Journal of Endocrinology, Jul 2007. pubmed.ncbi.nlm.nih.gov
  10. 10Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone-releasing peptide-2 on food intake Obesity (Silver Spring), Jun 2006. pubmed.ncbi.nlm.nih.gov
  11. 11Increased Secretion of Endogenous GH after Treatment with an Intranasal GH-releasing Peptide-2 Spray Does Not Promote Growth in Short Children with GH Deficiency Clinical Pediatric Endocrinology, Oct 2014. pubmed.ncbi.nlm.nih.gov
  12. 12Changes in appetite and body weight in response to long-term oral administration of the ghrelin agonist GHRP-2 in growth hormone deficient children Journal of Pediatric Endocrinology and Metabolism, Sep 2003. pubmed.ncbi.nlm.nih.gov
  13. 13Re-examination report for GHRP KAKEN100 Injection (注射用GHRP科研100, pralmorelin hydrochloride) (in Japanese) Pharmaceuticals and Medical Devices Agency (PMDA), Japan, 5 Feb 2014. pmda.go.jp
  14. 14GHRP KAKEN100 Injection (注射用GHRP科研100): summary of application data, origin and development (in Japanese) Kaken Pharmaceutical (published by PMDA), 2004. pmda.go.jp
  15. 15The combined administration of GH-releasing peptide-2 (GHRP-2), TRH and GnRH to men with prolonged critical illness evokes superior endocrine and metabolic effects compared to treatment with GHRP-2 alone Clinical Endocrinology, May 2002. pubmed.ncbi.nlm.nih.gov
  16. 16The somatotropic axis in critical illness: effect of continuous growth hormone (GH)-releasing hormone and GH-releasing peptide-2 infusion The Journal of Clinical Endocrinology & Metabolism, Feb 1997. pubmed.ncbi.nlm.nih.gov
  17. 17Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature Journal of Endocrinology, Oct 1997. pubmed.ncbi.nlm.nih.gov
  18. 18Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Comparison with the effects of GHRH, TRH and hCRH Peptides, 1997. pubmed.ncbi.nlm.nih.gov
  19. 19Growth hormone/insulin-like growth factor-1 response to acute and chronic growth hormone-releasing peptide-2, growth hormone-releasing hormone 1-44NH2 and in combination in older men and women with decreased growth hormone secretion Endocrine, Feb 2001. pubmed.ncbi.nlm.nih.gov
  20. 20Pharmacokinetics and pharmacodynamics of growth hormone-releasing peptide-2: a phase I study in children The Journal of Clinical Endocrinology & Metabolism, Apr 1998. pubmed.ncbi.nlm.nih.gov
  21. 21Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men The Journal of Clinical Endocrinology & Metabolism, Feb 2005. pubmed.ncbi.nlm.nih.gov
  22. 22Effects of eight months treatment with graded doses of a growth hormone (GH)-releasing peptide in GH-deficient children The Journal of Clinical Endocrinology & Metabolism, Jul 1998. pubmed.ncbi.nlm.nih.gov
  23. 23Determination of growth hormone releasing peptides (GHRP) and their major metabolites in human urine for doping controls by means of liquid chromatography mass spectrometry Analytical and Bioanalytical Chemistry, Aug 2011. pubmed.ncbi.nlm.nih.gov
  24. 24The effects of growth hormone-releasing peptide-2 (GHRP-2) on the release of growth hormone and growth performance in swine Domestic Animal Endocrinology, Apr 2000. pubmed.ncbi.nlm.nih.gov
  25. 25Drugs@FDA search for the active ingredient pralmorelin (openFDA drugsfda endpoint; no matches) U.S. Food and Drug Administration (openFDA), accessed 7 Oct 2026. api.fda.gov · data query
  26. 26Drugs@FDA search for active ingredients named GHRP (openFDA drugsfda endpoint; no matches) U.S. Food and Drug Administration (openFDA), accessed 7 Oct 2026. api.fda.gov · data query
  27. 27GHRP-2: safety testing results and vendor ratings (no published tests) Finnrick, accessed 7 Oct 2026. finnrick.com
  28. 28FDA drug recall (enforcement report) records naming GHRP, via the openFDA drug/enforcement API U.S. Food and Drug Administration (openFDA), 30 Sep 2026. api.fda.gov · data query
  29. 29Glycine-modified growth hormone secretagogues identified in seized doping material Drug Testing and Analysis, Feb 2019. pubmed.ncbi.nlm.nih.gov
  30. 30Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks U.S. Food and Drug Administration, 22 Apr 2026. fda.gov
  31. 31Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 14 May 2026. fda.gov
  32. 32Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act U.S. Food and Drug Administration, 14 May 2026. fda.gov
  33. 33Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 21 Mar 2025. fda.gov

Not medical advice. Talk to a licensed clinician before using any drug. Report an error.