GHRP-2: research, side effects and dosage in studies
In short
GHRP-2, also called pralmorelin, is a synthetic growth hormone releaser that has been studied in humans unusually often, including treatment lasting months in short children [1, 14]B. It has no marketing authorisation in Finland, and it releases other hormones besides growth hormone [6, 8]A.
- There are many human studies, mostly from the 1990s and 2000s. Most are short experiments that measured growth hormone secretion [3, 4, 7, 9]A.
- The longest treatment under the skin lasted eight months: six children with growth hormone deficiency received rising doses, and night-time growth hormone secretion rose with the dose, but IGF-1 did not rise [1]B. As a nasal spray, GHRP-2 was given to 15 short children for six months, and six of them continued for 18-24 months [14]B.
- Besides growth hormone, GHRP-2 raised cortisol [6]A and prolactin [8]A. It did not increase deep sleep in one study of seven men [8]A.
- In Finland, GHRP-2 is on Fimea's medicines list as pralmorelin, so it is controlled as a medicine [13]regulator. In sport it is banned at all times (WADA S2.2.4) [12]regulator.
- There is no approved dosage in Finland. All figures on this page are doses used in studies.
What is GHRP-2?
GHRP-2 is a synthetic growth hormone releasing peptide, also called pralmorelin [12]regulator. It makes the pituitary gland release the body's own growth hormone [1, 2]B.
GHRP-2 is not growth hormone; it makes the body produce it. Nor is it an analogue of IGF-1 like IGF-1 LR3, which acts at the lower end of the axis.
Reviews class GHRP-2 among the growth hormone releasers together with GHRP-6, hexarelin and ipamorelin, among others. More broadly it belongs to the unregulated substances marketed as "research compounds" that are used to act on the growth hormone and IGF-1 axis [5]. This site has pages on several of them: GHRP-6, hexarelin, ipamorelin, sermorelin and CJC-1295. GHRP-2 is one of the substances acting on growth hormone in the Peptides A-Z list.
Evidence at a glance
Each cell gives the kind of study and its source. The letter is the evidence level, not the result.
| Claimed effect | Humans | Animals | Cells |
|---|---|---|---|
| Growth hormone release | Dose-related rise, 8 months, 6 children [1]B; single dose into a vein, 10 children [2]B; nasal spray 6-24 months, 15 children [14]B | - | - |
| Combined effect with GHRH | Larger than either alone; varied with body mass index, sex hormones and age [3, 4]A | - | - |
| IGF-1 and IGFBP-3 | Did not rise during 8 months of treatment in children [1]B or with the nasal spray [14]B; rose during a 30-day infusion in older adults [19]B | - | - |
| Cortisol and prolactin | Cortisol rose, 42 men [6]A; prolactin rose briefly [8]A | - | - |
| Deep sleep regulation | Not supported: no effect on deep sleep, single dose, 7 men [8]A | - | - |
| Safety | No side effects or toxicity in the 8-month study, 6 children [1]B; nasal spray well tolerated, 15 children [14]B; harms of the group in a review [5] | - | - |
"-" = no such study is known.
What is GHRP-2 studied for?
In humans, GHRP-2 has mainly been studied as a tool for working out how growth hormone secretion is regulated, not as a treatment [3, 4, 7, 9]A. None of the uses below is approved in Finland.
- Growth hormone deficiency in children: GHRP-2 has been tried in short children and children with growth hormone deficiency, as a single dose into a vein, as an eight-month treatment under the skin and as a nasal spray for up to 18-24 months [1, 2, 14]B.
- Research on growth hormone regulation: in healthy adults, studies measured how sex hormones, body mass index, age and growth hormone given from outside change the response [3, 4, 7, 9, 10]A.
- Sleep: one study tested whether GHRP-2 increases deep sleep. It did not [8]A.
Muscle growth, fat loss and performance have not been studied, and according to a review these substances have no regulatory approval for such uses [5].
How does GHRP-2 work?
GHRP-2 makes the pituitary gland release growth hormone, and it works differently from growth hormone releasing hormone, GHRH [1]B. That is why the two have also been studied together: their combined effect is larger than either alone [3]A [4]A.
The effect is not limited to growth hormone. GHRP-2 also raised cortisol [6]A, and every GHRP-2 injection was followed by a brief rise in prolactin [8]A.
The effect also depends on the body's own growth hormone: growth hormone given from outside dampened the growth hormone release caused by GHRP-2 through negative feedback [10]A.
Has GHRP-2 been studied in humans?
Yes, and clearly more than most research peptides covered on this site. There are many human studies, mostly from the 1990s and 2000s. Most are physiology studies that use GHRP-2 as a tool to study how growth hormone secretion is regulated, not as a treatment.
Human studies
- Pharmacokinetics in children. Ten prepubertal short children, nine boys and one girl, mean age 7.7 years, received a single dose of 1 microgram per kilogram into a vein over one minute. Nine blood samples were taken over two hours. GHRP-2 raised growth hormone predictably, and its elimination followed two exponential phases [2]B.
- Longest treatment under the skin: eight months. Six prepubertal children with growth hormone deficiency and growth failure received rising doses under the skin in two-month periods: first 0.3, then 1.0 and then 3.0 micrograms per kilogram per day. In a fourth two-month period they received 3.0 micrograms of GHRP-2 together with 3.0 micrograms of GHRH. At the end of each period, 12-hour overnight growth hormone secretion and toxicity were measured. GHRP-2 raised night-time growth hormone secretion with the dose, but the effect was brief and barely seen later in the night. IGF-1 and IGFBP-3 did not rise. Growth velocity was higher during treatment than before and after it [1]B.
- Longest treatment: nasal spray for up to two years. 15 short children, half of them with growth hormone deficiency, received GHRP-2 as a nasal spray twice a day for three months and three times a day after that. All 15 took part for six months, and six of them continued for 18-24 months. Growth velocity rose from 3.7 cm a year to 6.1 cm a year at six months and was 6.0 cm a year at 18-24 months. IGF-1 and IGFBP-3 did not change significantly, and the treatment was well tolerated. Growth was compared with the children's own baseline, not with a control group [14]B.
- Physiology studies in adults. Several randomised studies used GHRP-2 in healthy adults to study growth hormone regulation: the effect of sex hormones and body mass index [3]A, the combined effect with GHRH [4]A, the effect of ageing [7]A and the effect of testosterone [9, 10]A. Their aim was physiology, not treatment.
The strongest treatment evidence comes from these two studies in children, and they should be read carefully: the children were short or had growth hormone deficiency, and neither study had a control group [1, 14]B. The result does not tell what the substance does in a healthy adult.
Who studies GHRP-2?
GHRP-2 has been studied in humans since the 1990s, both in children [1, 2]B and in healthy adults [3, 4, 7, 9, 10]A. The newer adult studies were done at the Mayo Clinic in the United States, where GHRP-2 served as a measuring tool in research on growth hormone regulation [3, 4, 9]A.
Newer review literature mainly deals with the group being sold and self-administered without regulatory approval [5].
Who wrote this page: the editorial team
This page was written by the Molecular Recovery editorial team. The draft was made with the help of AI, and the claims were checked against the sources (AI policy). The page has not been medically reviewed. How we work: About us.
How long does GHRP-2 stay in the body?
GHRP-2 leaves the blood quickly: in children, the half-life of a single dose given into a vein averaged 0.55 hours, about half an hour [2]B.
In the same study, growth hormone peaked about 25 minutes after the dose [2]B. In the eight-month study, the effect of an injection under the skin on growth hormone was brief and barely seen later in the night [1]B.
What are the side effects of GHRP-2?
In the eight-month study in children, no side effects or toxicity were observed, but only six children took part [1]B. The nasal spray was well tolerated in a study of 15 children [14]B. Harms of the substance group are described in a review [5].
Measured in humans
In the eight-month treatment under the skin, toxicity was measured at the end of every two-month period and no harms were found [1]B. GHRP-2 given as a nasal spray was well tolerated when 15 children used it for six months and six of them for 18-24 months [14]B.
GHRP-2 does not release growth hormone alone. In a study of 42 healthy men, peak cortisol was 616 nmol/l after GHRP-2, against an average of 420 nmol/l after saline [6]A. In a sleep study of seven men, every GHRP-2 injection was followed by a brief rise in prolactin [8]A. The rise in prolactin and cortisol has been measured most precisely with hexarelin, for which dose-response curves for prolactin and cortisol have been published separately.
Harms reported for the group
Among peptides marketed as "research compounds" that act on the growth hormone and IGF-1 axis, reported problems include hormonal and metabolic disturbances such as rises in prolactin and cortisol, appetite changes and blood glucose disturbances, as well as fluid retention, muscle and joint pain and injection-site reactions. The review covers the group, not GHRP-2 alone [5].
What has not been studied
There are no published data on long-term use in healthy adults. The longest treatment studies were done in short children: eight months under the skin in six children [1]B and 18-24 months as a nasal spray in six children [14]B. Performance or physique use has not been studied, and according to a review these substances have no regulatory approval for such uses [5]. Peptide harms in general: side effects in studies.
Interactions and who has no data
No studies of drug interactions are known. All that is known is that growth hormone given from outside dampened the effect of GHRP-2 [10]A and that testosterone changed the response [9, 10]A.
The human studies included children with short stature or growth hormone deficiency [1, 2]B and healthy adults, mostly men [3, 6, 8]A. No data are known for pregnancy or breastfeeding.
Evidence against and what is unknown
One often repeated claim has been tested and refuted, and the response varies a lot from person to person.
Evidence against
- Sleep. Growth hormone releasers have been claimed to improve sleep. In a randomised study of seven young men, GHRP-2 given late at night did not increase deep sleep, although growth hormone rose. The authors say the result argues against this hormone system regulating deep sleep in humans [8]A.
- The response is not constant. Body mass index and sex hormones determined how large a growth hormone response GHRP-2 together with GHRH produced [3]A. Abdominal visceral fat, age and IGF-1 explained much of the variation in the combined effect of GHRH and GHRP-2 [4]A, and age weakened the body's own regulation of growth hormone [7]A. The same dose therefore gives different results in different people.
- Dependence on the body's own state. Growth hormone given from outside dampened the growth hormone release caused by GHRP-2 [10]A.
- No IGF-1 rise in children. During eight months of treatment, IGF-1 and IGFBP-3 did not rise [1]B, and they did not change significantly with the nasal spray either [14]B. In healthy older adults, by contrast, a 30-day continuous infusion under the skin raised IGF-1 and IGFBP-3 [19]B.
What the evidence does not support
- "GHRP-2 builds muscle, burns fat or improves performance": none of this has been studied, and according to a review approval is lacking [5].
- "GHRP-2 is an approved medicine in Finland": it has no marketing authorisation in Finland.
- "The dose for a healthy adult is known": the published doses come from studies in children and physiology experiments [1, 2]B.
- "The effect is limited to growth hormone": cortisol and prolactin also rose [6, 8]A.
What is not known
- What long-term use does to a healthy adult. The longest published treatments were done in short children [1, 14]B.
- Whether GHRP-2 works by mouth over the long term. A single dose by mouth has been described as raising growth hormone in healthy children [15], but no study of long-term use by mouth is known.
GHRP-2 dosage in studies
GHRP-2 has no approved dosage in Finland. Below are the doses used in human studies. They are not recommendations.
| Study | Who | Dose and route | Duration |
|---|---|---|---|
| Pihoker 1998 | 10 prepubertal short children, mean age 7.7 years | 1 µg/kg into a vein over one minute | single dose, 2 hours of follow-up [2]B |
| Mericq 1998 | 6 prepubertal children with growth hormone deficiency | 0.3, then 1.0, then 3.0 µg/kg per day under the skin; in the fourth period 3.0 µg/kg together with GHRH 3.0 µg/kg | 4 x 2 months [1]B |
| Pihoker 1997 | 15 short children, half of them with growth hormone deficiency | 5-15 µg/kg as a nasal spray twice a day for 3 months, then three times a day | 6 months, 6 children 18-24 months [14]B |
| Moreno-Reyes 1998 | 7 healthy young men; saline as control | 1 µg/kg into a vein late at night | single dose [8]A |
| Veldhuis 2004 | 13 healthy men aged 43-71 | 1 µg/kg into a vein | single dose [10]A |
What the numbers do not tell you. The longest treatment studies were done in short children or children with growth hormone deficiency [1, 14]B. The dose cannot be transferred to a healthy adult: the starting point, the aim and the risks differ. Single doses into a vein in physiology studies are not treatment doses but test stimuli. The response also varies with body mass index, sex hormones and age [3, 4]A, so the same amount does not have the same effect in two people. A fuller table with sources: GHRP-2 doses used in studies. Unit converter: GHRP-2 calculator.
GHRP-2 or GHRP-6: what is the difference?
GHRP-2 and GHRP-6 are both growth hormone releasing peptides, but no published study is known that compares their effect directly in the same setting.
Both raised other hormones besides growth hormone. In a GHRP-6 study in healthy men, ACTH and cortisol rose [16]B. GHRP-2 raised cortisol [6]A and prolactin [8]A. Because the two have not been compared in the same people, these figures do not show which raises hormones more.
GHRP-2 has mainly been compared with GHRH: GHRP-2 raised cortisol, GHRH did not [6]A. GHRP-6's own studies and harms: GHRP-6.
Is GHRP-2 legal in Finland?
GHRP-2 has no marketing authorisation in Finland, so it may not be sold or marketed as a medicine. It is named on Fimea's medicines list, so in Finland it is controlled as a medicine [13]regulator.
- Medicines list. Annex 1 of Fimea's decision 230/2025 names "Pralmoreliini, (GHRP-2)", and Annex 1 A names its analogue Gly-GHRP-2. Substances in Annex 1 A are always treated, by their effect, like prescription-only medicines [13]regulator.
- Fimea's warning. Fimea has specifically warned against using injectable peptides bought online [11]regulator.
- Japan. In Japan, pralmorelin was approved on 22 Oct 2004 as a diagnostic agent for testing endocrine function (trade name GHRP, Kaken Pharmaceutical) [18]regulator. According to a 2004 drug profile, the use is testing pituitary function [17]. It is not approved as a treatment, and it has no marketing authorisation in the EU or Finland.
- The label "research use only" is a classification label, not a permit for human use. Even a broad base of human research does not make a substance an approved medicine.
Overview of the law: peptides and the law in Finland. Bringing them from abroad: Travelling with peptides.
This is not legal advice. Disclaimer.
Is GHRP-2 doping?
Yes. WADA's 2026 Prohibited List names GHRP-2 in the group of growth hormone releasing peptides as "GHRP-2 (pralmorelin)" (S2.2.4). Substances in class S2 are banned at all times, in and out of competition [12]regulator.
How to assess a GHRP-2 product
There is no certainty about the contents of a GHRP-2 product without analysis. On a certificate of analysis (COA), check the test method and that the batch number matches the vial.
Liquid chromatography (HPLC) shows purity; mass spectrometry (MS) shows whether the molecule is the right one. A purity percentage without the method is just a number. How to read one: how to read a COA.
The product is sold as GHRP-2 and as GHRP-2 acetate. Acetate refers to the salt form used in making peptides; it is not a different active substance. GHRP-2 and GHRP-6, on the other hand, are different molecules, so it is worth checking the label.
What a certificate does not tell you: sterility, endotoxin content, or what happened to the product in transport. On handling: mixing and storage.
FAQ
What is the GHRP-2 peptide?
GHRP-2, also called pralmorelin, is a synthetic growth hormone releasing peptide: it makes the pituitary gland release the body's own growth hormone [1, 2]B [12]regulator. It has no marketing authorisation in Finland.
What is the GHRP-2 dosage?
There is no approved dosage. The published doses are 0.3-3.0 micrograms per kilogram per day under the skin in two-month periods in children with growth hormone deficiency [1]B, and a single dose of 1 microgram per kilogram into a vein in physiology experiments [2]B [8]A. Neither is guidance for a healthy adult.
GHRP-2 or GHRP-6?
No direct comparison of their effect is known. Both are growth hormone releasers. GHRP-2 raised cortisol and prolactin besides growth hormone [6, 8]A, and GHRP-6 raised ACTH and cortisol [16]B.
What is GHRP-2 acetate?
Acetate is a salt form used in making peptides. It is not a different active substance from GHRP-2.
Does GHRP-2 work by mouth?
A single dose by mouth has been described as raising growth hormone in healthy children [15]. No study of long-term use by mouth is known. In the treatment studies GHRP-2 was given under the skin [1]B or as a nasal spray [14]B.
Does GHRP-2 improve sleep?
The evidence does not support it. In a randomised study of seven men, a single dose did not increase deep sleep, although growth hormone rose [8]A.
What side effects does GHRP-2 have?
No harms were seen in the eight-month study in children, but there were only six children [1]B. GHRP-2 raised cortisol and prolactin [6, 8]A. Users of the substance group have also reported appetite changes, blood glucose disturbances, fluid retention, muscle and joint pain and injection-site reactions [5].
GHRP-2 experiences: what do studies say?
User accounts of GHRP-2 have not been compiled on this site. In studies GHRP-2 raised cortisol and prolactin besides growth hormone [6, 8]A, and it was well tolerated in the treatment studies in children [1, 14]B.
Is GHRP-2 legal in Finland?
It has no marketing authorisation in Finland, and it is on Fimea's medicines list as pralmorelin, so it is controlled as a medicine [13]regulator. Fimea has warned against using injectable peptides bought online [11]regulator. This is not legal advice.
Is GHRP-2 doping?
Yes. GHRP-2 (pralmorelin) is named in section S2.2.4 of WADA's 2026 Prohibited List and is banned at all times [12]regulator.
Read the research yourself: sources
Every source opens the original publication or the regulator's page. The level shows what the source itself reports.
- Mericq V, Cassorla F, Salazar T, et al. Effects of eight months treatment with graded doses of a growth hormone (GH)-releasing peptide in GH-deficient children. J Clin Endocrinol Metab. 1998;83:2355-2360. PMID 9661608 B
- Pihoker C, Kearns GL, French D, Bowers CY. Pharmacokinetics and pharmacodynamics of growth hormone-releasing peptide-2: a phase I study in children. J Clin Endocrinol Metab. 1998;83:1168-1172. PMID 9543135 B
- Paulo RC, Cosma M, Soares-Welch C, et al. Gonadal status and body mass index jointly determine growth hormone (GH)-releasing hormone/GH-releasing peptide synergy in healthy men. J Clin Endocrinol Metab. 2008;93:944-950. PMID 18073313 A
- Veldhuis JD, Bowers CY. Determinants of GH-releasing hormone and GH-releasing peptide synergy in men. Am J Physiol Endocrinol Metab. 2009;296:E1085-E1092. PMID 19240251 A
- Dominikowski A, Rękoś Z, Olejarz M, et al. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol (Lausanne). 2026;17:1822475. PMID 42395176 (review)
- 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;162:1043-1049. PMID 20299490 A
- Veldhuis JD, Iranmanesh A, Bowers CY. Joint mechanisms of impaired growth-hormone pulse renewal in aging men. J Clin Endocrinol Metab. 2005;90:4177-4183. PMID 15811926 A
- Moreno-Reyes R, Kerkhofs M, L'Hermite-Balériaux M, et al. Evidence against a role for the growth hormone-releasing peptide axis in human slow-wave sleep regulation. Am J Physiol. 1998;274:E779-E784. PMID 9612233 A
- Norman C, Miles J, Bowers CY, Veldhuis JD. Differential pulsatile secretagogue control of GH secretion in healthy men. Am J Physiol Regul Integr Comp Physiol. 2013;304:R712-R719. PMID 23485864 A
- Veldhuis JD, Evans WS, Iranmanesh A, et al. Short-term testosterone supplementation relieves growth hormone autonegative feedback in men. J Clin Endocrinol Metab. 2004;89:1285-1290. PMID 15001624 A
- Fimea. Fimea warns: do not use injectable peptides purchased online (29 Jun 2026). Fimea regulator
- World Anti-Doping Agency. 2026 Prohibited List, section S2.2.4: "GHRP-2 (pralmorelin)". WADA regulator
- Finland. Lääkeluettelo (Fimea medicines list), 230/2025, section 2, annex 1 ("Pralmoreliini, (GHRP-2)") and annex 1 A ("GHRP-2 analogi (Gly-GHRP-2)"). Finlex regulator
- Pihoker C, Badger TM, Reynolds GA, Bowers CY. Treatment effects of intranasal growth hormone releasing peptide-2 in children with short stature. J Endocrinol. 1997;155:79-86. PMID 9390009 B
- Argente J, García-Segura LM, Pozo J, Chowen JA. Growth hormone-releasing peptides: clinical and basic aspects. Horm Res. 1996;46:155-159. PMID 8950613 (review)
- Frieboes RM, Murck H, Maier P, et al. Growth hormone-releasing peptide-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man. Neuroendocrinology. 1995;61:584-589. PMID 7617137 B
- Pralmorelin: GHRP 2, GPA 748, growth hormone-releasing peptide 2, KP-102 D, KP-102 LN, KP-102D, KP-102LN. Drugs R D. 2004;5:236-239. Drug profile. PMID 15230633 (review)
- KEGG DRUG D02040: Pralmorelin dihydrochloride (GHRP, Kaken Pharmaceutical). Therapeutic category 7223, diagnostic reagents for endocrine function; listed among new drug approvals in Japan, 22 Oct 2004. Read 14 Oct 2026. KEGG regulator
- Bowers CY, Granda R, Mohan S, et al. Sustained elevation of pulsatile growth hormone (GH) secretion and insulin-like growth factor I (IGF-I), IGF-binding protein-3 (IGFBP-3), and IGFBP-5 concentrations during 30-day continuous subcutaneous infusion of GH-releasing peptide-2 in older men and women. J Clin Endocrinol Metab. 2004;89:2290-2300. PMID 15126555 B
Sources read 13 Oct 2026; PubMed records, the WADA Prohibited List, Fimea's medicines list and the KEGG record checked 14 Oct 2026.
Evidence levels: A = randomised human trial or meta-analysis · B = observational human study or case series · C = animal study · D = cell or laboratory study · E = not peer-reviewed · regulator = a regulator's assessment or decision, not research evidence. The marker official means official product information (summary of product characteristics or label); it is not research evidence. For a review, the level shows what kind of research the statement rests on. No level: statements that something has not been studied, reviews' interpretations, named hypotheses and the general rules in our certificate-of-analysis guide.
Content is general information about research, not medical advice. If you have symptoms, contact a healthcare professional.