GHRP-6: research, side effects and dosage in studies
In short
GHRP-6 is a synthetic peptide of six amino acids that makes the pituitary gland release growth hormone [1]C. It has no marketing authorisation as a medicine [11]regulator.
- In small studies in healthy men from the 1980s and 1990s, GHRP-6 given into a vein raised growth hormone quickly [3, 5]B.
- It can also raise the stress hormones ACTH and cortisol [6]B. The FDA also lists blood glucose as a concern [10]regulator.
- There are no controlled human studies on muscle, fat or recovery [9].
- In a randomised phase 3 trial in 188 stroke patients, GHRP-6 given into a vein together with another protein, epidermal growth factor (EGF), for 7 days did not reduce disability compared with standard care [16]A.
- GHRP-6 is listed in Annex 1 A of Fimea's medicines list, so in Finland it is controlled as a medicine and always treated like a prescription-only medicine [12]regulator. In sport it is banned at all times (WADA S2.2.4) [13]regulator.
What is GHRP-6?
GHRP-6 (growth hormone releasing hexapeptide) is a synthetic six-amino-acid peptide. Its sequence is His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, and it releases growth hormone by acting directly on the pituitary gland [1]C.
GHRP-6 was developed in the 1980s, before the body's own matching hormone was known. Research on it led to the discovery of the growth hormone secretagogue receptor and finally, in 1999, of ghrelin [2].
GHRP-6 belongs to the same group of substances as ipamorelin, hexarelin and GHRP-2 (GHRP-2 or GHRP-6). According to a review, these substances are sold as "research compounds" without regulatory approval for physique use [9]. Basics: What are peptides?. All substances: Peptides A-Z.
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 rise | 17 healthy men, single infusion into a vein; dose-related rise [3]B | Released growth hormone in several animal species [1]C | Released growth hormone from pituitary cells [1]D |
| IGF-1 rise | 9 young men, 34-hour infusion; IGF-1 rose [5]B | - | - |
| Muscle, fat, recovery | No controlled human studies [9] | Repeated doses increased weight gain in young rats [1]C | - |
| Appetite | No controlled human study | Given directly into the brain of rats, it increased eating [8]C | - |
| Sleep | Light sleep increased in healthy men [6]B | - | - |
| Recovery after stroke (with EGF) | Phase 3, 188 patients, 7 days into a vein: no difference from standard care in disability or survival [16]A | - | - |
| Safety | Single doses well tolerated in short studies [3, 7]B; ACTH and cortisol rose [6]B; stroke trial: serious adverse events in 30 of 95 treated patients, none judged treatment-related [16]A; no long-term data [9] | - | - |
"-" = no such study is known.
What is GHRP-6 studied for?
None of the uses below is approved, because GHRP-6 has no marketing authorisation in the EU or EEA [11, 14]regulator.
- Growth hormone regulation: small human studies in healthy men measured how growth hormone, IGF-1 and other hormones change [3, 4, 5, 6]B.
- Stroke: in Cuba, GHRP-6 has been tested together with epidermal growth factor (EGF) in acute ischaemic stroke, in two randomised trials [15, 16]A.
- Hormone tests: GHRP-6 has been tried as a test that activates the adrenal axis when investigating adrenal insufficiency [7]B.
- Appetite: in rats, GHRP-6 given directly into the brain increased eating [8]C. Appetite is covered with the side effects: What are the side effects of GHRP-6?.
Claims online. Online, GHRP-6 is described as a muscle builder and a way to speed up recovery. According to a review, the physique benefits of peptides acting on the growth hormone axis are uncertain, and there are no controlled human studies of them [9].
How does GHRP-6 work?
GHRP-6 makes the pituitary gland release growth hormone. In laboratory studies it released growth hormone from pituitary cells, and in animals the effect depended on the dose [1]D [1]C. It did not release LH, FSH, TSH or prolactin at the same time [1]C.
GHRP-6 acts on the same receptor as the body's own hormone ghrelin, discovered later. Research on GHRP-6 is what led to the discovery of this receptor and of ghrelin [2].
The effect is not limited to growth hormone. In healthy men repeated doses also raised ACTH and cortisol [6]B, and in rats GHRP-6 given into the brain increased eating without growth hormone explaining it [8]C.
Has GHRP-6 been studied in humans?
Yes. Most are small, short hormone studies: they included, for example, 17, 5 and 9 healthy men, and they measured hormone levels over a few hours to a day and a half [3, 4, 5]B. In addition, two randomised trials in Cuba gave GHRP-6 together with epidermal growth factor (EGF) to stroke patients for 7 days [15, 16]A. Muscle, fat and recovery from training have not been measured [9].
Human studies
- First human study (1989). 17 healthy men received GHRP-6 as a 30-minute infusion into a vein, and some received saline for comparison. Growth hormone rose in a dose-related way and peaked at about 45 minutes. LH, FSH, TSH and ACTH did not change with these single doses [3]B.
- By mouth (1992). In five healthy men and nine children of short stature, GHRP-6 taken by mouth raised growth hormone, but it had only about 0.3% of the activity of an intravenous dose [4]B.
- Long infusion (1993). In nine young men, a 34-hour infusion made growth hormone pulses larger, but their number did not change. IGF-1 rose on average from 252 to 312 micrograms per litre [5]B.
- Sleep and stress hormones (1995). Healthy men received four intravenous doses during the night. Besides growth hormone, ACTH and cortisol rose compared with placebo, and the amount of light sleep (stage 2) increased [6]B.
- Adrenal test (2010). GHRP-6 was tried as a test for adrenal insufficiency, but it was less accurate than the standard test [7]B.
- Stroke (2024 and 2026). In two randomised, open-label trials in Cuba, patients with acute ischaemic stroke received GHRP-6 into a vein together with epidermal growth factor (EGF), twice a day for 7 days, or standard care. The first trial (36 patients) looked mainly at safety [15]A. In the phase 3 COURAGE-2 trial (188 patients) there was no difference from standard care in disability, daily activities or survival. Serious adverse events occurred in 30 of 95 treated patients and 18 of 93 on standard care, and the investigators judged none of them to be caused by the treatment. A possible benefit was seen mainly in a small subgroup with severe strokes [16]A. Because GHRP-6 was always given with EGF, its own share of any effect cannot be separated.
Seen in animals, not studied in humans
These findings come from animals and have not been tested in controlled human studies. Results of animal studies cannot be transferred directly to humans.
-
Growth and weight no human studies
In young rats, repeated doses of GHRP-6 increased weight gain [1]C.
If it held in humans: the substance could affect body composition or weight.
Why it might not translate: weight gain does not show whether it is muscle, fat or fluid, and the growth of young rats differs from the body of an adult human [1]C.
Evidence now: animal studies from 1984 [1]. No controlled human study on muscle or fat [9].
Who studies GHRP-6?
GHRP-6 was developed by Cyril Bowers' research group in the 1980s [1]C [2]. Later the substance was used as a tool in hormone research on the regulation of growth hormone and the adrenal axis [3, 5, 6, 7]B.
The largest human trials come from Cuba, where the Center for Genetic Engineering and Biotechnology (CIGB) has studied GHRP-6 together with EGF in stroke [15, 16]A. Otherwise newer literature deals mainly with the fact that this group of substances is sold and self-administered without regulatory approval [9].
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-6 stay in the body?
There are no exact data on the half-life of GHRP-6 in humans. After a 30-minute infusion into a vein, growth hormone peaked at about 45 minutes [3]B.
Taken by mouth, GHRP-6 had only about 0.3% of the activity of an intravenous dose, so taken by mouth it was much less active [4]B.
What are the side effects of GHRP-6?
In short studies single doses were well tolerated, and no side effects were detected in the adrenal test [3, 7]B. In the phase 3 stroke trial, serious adverse events occurred in 30 of 95 patients given GHRP-6 with EGF and in 18 of 93 on standard care; the investigators judged none to be caused by the treatment [16]A. There are no human studies of use longer than 7 days [9, 16].
Hormonal effects
In healthy men repeated doses raised ACTH and cortisol [6]B. According to the FDA, there is little safety information on GHRP-6, but the available data reveal concerns about effects on cortisol and a rise in blood glucose due to reduced insulin sensitivity [10]regulator.
Appetite
In rats, GHRP-6 given directly into a brain ventricle increased eating in a dose-related way, and the effect was not due to growth hormone [8]C. According to the developer of GHRP-6, increased food intake was the first sign that the substance has effects other than growth hormone release [2]. The effect on appetite has not been studied in controlled human studies, but according to a review, appetite changes have been reported by users of this group of substances [9].
Harms reported for the group
According to a 2026 review, users of peptides acting on the growth hormone axis have reported prolactin and cortisol rises, appetite changes, blood sugar disturbances, fluid retention, muscle and joint pain and injection-site reactions. The review covers the group of substances, not GHRP-6 alone [9].
Risks in products
According to the FDA, products may carry a risk of immune reactions, because the peptide can form aggregates and products may contain impurities [10]regulator. More: Side effects and safety.
Interactions and who has no data
There are no study data on interactions with other medicines. Because according to the FDA GHRP-6 can raise blood glucose and cortisol [10]regulator, there are no data on its effects in people with diabetes or adrenal disease.
The hormone studies included mainly healthy men [3, 5, 6]B. One study also included nine children of short stature, who received a single dose by mouth [4]B. Women took part only in the stroke trials, in which GHRP-6 was given with EGF [15, 16]A. There are no data on pregnancy or breastfeeding.
Evidence against and what is unknown
The human studies measured hormone levels, not benefits. GHRP-6 also affects hormones other than growth hormone [6]B.
Evidence against
- Repeated doses raised the stress hormones ACTH and cortisol [6]B.
- Taken by mouth it had only about 0.3% of the intravenous activity [4]B.
- As an adrenal test, GHRP-6 was less accurate than the standard test [7]B.
- The phase 3 stroke trial COURAGE-2 missed its main goal: GHRP-6 with EGF did not reduce disability compared with standard care [16]A.
What the evidence does not support
- "GHRP-6 raises only growth hormone": not only. ACTH and cortisol also rose [6]B, and GHRP-6 has even been used as a test that activates the adrenal axis [7]B. The FDA lists effects on cortisol and blood glucose as a concern [10]regulator.
- "The muscle benefits have been shown in humans": human studies mainly measured hormone levels over a few hours or days [3, 5, 6]B. According to a review, physique benefits are uncertain [9].
- "GHRP-6 is a freely available research chemical in Finland": it is not. GHRP-6 is listed in Annex 1 A of Fimea's medicines list, so in Finland it is controlled as a medicine [12]regulator.
What is not known
- What long-term use does. The longest human studies lasted 7 days, and in them GHRP-6 was given with EGF to stroke patients [15, 16]A; the hormone studies in healthy people lasted at most about a day and a half [5]B.
- Whether GHRP-6 increases appetite in humans. A clear eating effect has been shown in rats when the substance was given directly into the brain [8]C.
- How GHRP-6 affects blood glucose and insulin sensitivity. According to the FDA, data are limited [10]regulator.
GHRP-6 dosage in studies
There is no approved dosing, because GHRP-6 has no marketing authorisation [11]regulator. Below are the doses used in human studies. They were given into a vein or by mouth under supervised conditions, and they are not recommendations.
| Study | Who | Dose and route | Duration |
|---|---|---|---|
| Ilson 1989 | 17 healthy men | 0.05-2.5 µg/kg as a 30-minute infusion into a vein | single dose [3]B |
| Bowers 1992 | 5 healthy men and 9 children of short stature | 100 or 300 µg/kg by mouth (children 300 µg/kg); about 0.3% of intravenous activity | single doses [4]B |
| Jaffe 1993 | 9 healthy young men | 1 µg/kg into a vein, then 1 µg/kg per hour as an infusion | 34 hours [5]B |
| Frieboes 1995 | healthy men | four 50 µg doses into a vein during the night | one night [6]B |
| Alaioubi 2010 | 49 patients with suspected pituitary-adrenal axis disorder and 20 healthy controls | 1 µg/kg into a vein as a test | single dose [7]B |
| Hernández-Bernal 2024 (phase 1-2) | 36 stroke patients: 10 + 10 received GHRP-6, 16 standard care | 3.5 mg or 5 mg into a vein twice a day, together with EGF (75 µg) | 7 days [15]A |
| COURAGE-2, Hernández-Bernal 2026 (phase 3) | 188 stroke patients: 95 received the combination, 93 standard care | 5 mg into a vein twice a day, together with EGF (75 µg) | 7 days [16]A |
What the numbers do not tell you. The doses were given under hospital conditions, to measure hormones or, in the stroke trials, as an experimental treatment together with EGF. They do not show what dose would be safe or useful. A fuller table with sources: GHRP-6 doses used in studies. Unit converter: GHRP-6 calculator.
Status in the United States
In the United States, the FDA has placed GHRP-6 in compounding category 2 (outsourcing-facility list, 503B, added 29 Sep 2023), for substances that may present significant safety risks [10]regulator.
Is GHRP-6 legal in Finland?
GHRP-6 is listed in Annex 1 A of Fimea's medicines list [12]regulator. Annex 1 A substances are controlled as medicines in Finland and are always treated like prescription-only medicines. GHRP-6 has no marketing authorisation [11]regulator.
- Medicines list. Annex 1 A of Fimea decision 230/2025 names "GHRP-6, growth hormone releasing hexapeptide" and its analogue Gly-GHRP-6. Substances in annex 1 A are always treated, because of their effects, like prescription-only medicines [12]regulator.
- Marketing authorisation. On 12 Oct 2026 EMA's data on centrally authorised medicines contained no medicine with GHRP-6 [11]regulator, and the Article 57 database had no GHRP-6 product in any EU or EEA country (data as of 21 Sep 2026) [14]regulator.
- Import. Ordering medicines from outside the EU is covered on Peptides and the law. Bringing them back from travel: Travelling with peptides.
This is not legal advice. Disclaimer.
Is GHRP-6 doping?
Yes. On the WADA 2026 Prohibited List, GHRP-6 is named among growth hormone releasing factors (S2.2.4). Class S2 substances are prohibited at all times, in and out of competition [13]regulator.
How to assess a GHRP-6 product
You cannot be sure of the content. According to a review, product composition and dose are uncertain in unregulated supply chains [9]. According to the FDA, GHRP-6 products may contain peptide-related impurities, and the peptide may form aggregates that raise the risk of immune reactions [10]regulator.
A seller's own certificate of analysis (COA) does not by itself show that a product is pure or that the vial contains GHRP-6. At the very least the certificate should identify the substance by mass spectrometry (MS) and refer to the same batch as the vial. More: How to read a COA and check a test result. Handling: Mixing and handling.
FAQ
What is GHRP-6?
A synthetic six-amino-acid peptide that makes the pituitary gland release growth hormone [1]C. Research on it led to the discovery of ghrelin [2].
GHRP-6 experiences: what do studies show?
User accounts of this substance have not been compiled on this site. In small human studies GHRP-6 raised growth hormone and also cortisol [3, 6]B, but there are no controlled human studies of muscle benefits [9].
GHRP-6 side effects: what is known?
According to the FDA, the concerns are effects on cortisol and blood glucose and a risk of immune reactions [10]regulator. There are no human studies of long-term use [9].
GHRP-6 and appetite: does it make you hungry?
Not known in humans. In rats, GHRP-6 given directly into the brain increased eating [8]C. According to a review, appetite changes have been reported by users of this group of substances [9].
GHRP-6 dosage: what did studies use?
We do not give dosing instructions. Doses used in studies are listed under GHRP-6 dosage in studies, and they were given into a vein under supervised conditions [3, 5]B. They are not a recommendation.
GHRP-6 vs ipamorelin: what is the difference?
Both belong to the same group of growth hormone secretagogues [9]. There are no human studies comparing them. Ipamorelin has its own page: Ipamorelin.
GHRP-6 in Finland: is it legal?
GHRP-6 is listed in Annex 1 A of Fimea's medicines list, so in Finland it is controlled as a medicine and always treated like a prescription-only medicine [12]regulator. There is no authorised GHRP-6 medicine [11]regulator. This is not legal advice.
GHRP-6 and doping: is it banned?
Yes. GHRP-6 is named in class S2.2.4 of the WADA 2026 Prohibited List and is banned at all times [13]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.
- Bowers CY, Momany FA, Reynolds GA, Hong A. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology. 1984;114(5):1537-1545. PMID 6714155 C
- Bowers CY. History to the discovery of ghrelin. Methods Enzymol. 2012;514:3-32. PMID 22975043 (review)
- Ilson BE, Jorkasky DK, Curnow RT, Stote RM. Effect of a new synthetic hexapeptide to selectively stimulate growth hormone release in healthy human subjects. J Clin Endocrinol Metab. 1989;69(1):212-214. PMID 2543692 B
- Bowers CY, Alster DK, Frentz JM. The growth hormone-releasing activity of a synthetic hexapeptide in normal men and short statured children after oral administration. J Clin Endocrinol Metab. 1992;74(2):292-298. PMID 1730807 B
- Jaffe CA, Ho PJ, Demott-Friberg R, Bowers CY, Barkan AL. Effects of a prolonged growth hormone (GH)-releasing peptide infusion on pulsatile GH secretion in normal men. J Clin Endocrinol Metab. 1993;77(6):1641-1647. PMID 7903313 B
- 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(5):584-589. PMID 7617137 B
- Alaioubi B, Mann K, Petersenn S. Diagnosis of adrenal insufficiency using the GHRP-6 Test: comparison with the insulin tolerance test in patients with hypothalamic-pituitary-adrenal disease. Horm Metab Res. 2010;42(3):198-203. PMID 19946832 B
- Locke W, Kirgis HD, Bowers CY, Abdoh AA. Intracerebroventricular growth-hormone-releasing peptide-6 stimulates eating without affecting plasma growth hormone responses in rats. Life Sci. 1995;56(16):1347-1352. PMID 8614257 C
- 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)
- U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 22 Apr 2026). FDA regulator
- European Medicines Agency. Medicine data (data set of 12 Oct 2026): no product with GHRP-6. EMA regulator
- Finland. Lääkeluettelo (Fimea medicines list), 230/2025, section 2 and annex 1 A. Finlex regulator
- World Anti-Doping Agency. 2026 Prohibited List, section S2.2.4. WADA regulator
- European Medicines Agency. Article 57 product data (EMA/518502/2018 Rev.89, data as of 21 Sep 2026): no product with GHRP-6 in any EU/EEA country. EMA regulator
- Hernández-Bernal F, Estenoz-García D, Gutiérrez-Ronquillo JH, et al. Combination therapy of Epidermal Growth Factor and Growth Hormone-Releasing Hexapeptide in acute ischemic stroke: a phase I/II non-blinded, randomized clinical trial. Front Neurol. 2024;15:1303402. PMID 38638315 A
- Hernández-Bernal F, Subirós-Martínez N, Gutiérrez-Ronquillo JH, et al. Phase III Open-Label, Randomized Clinical Trial of Epidermal Growth Factor and Growth Hormone Releasing Hexapeptide in Acute Ischemic Stroke (COURAGE-2). J Clin Neurosci. 2026;152:112195. PMID 42462342 A
Sources checked 12 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.