GHRP-2, GHRP-6 and Hexarelin
GHRP-2, GHRP-6 and hexarelin are three synthetic ghrelin-receptor peptides. Here is what is known about identity, diagnostic use, trials, safety and regulatory status.
Content last updated . This page has not been medically reviewed.
Overview and classification
GHRP-2, GHRP-6 and hexarelin are synthetic peptides that switch on the receptor for ghrelin, the "hunger hormone", and so prompt the pituitary gland to release growth hormone. [1] They are investigational compounds, not approved treatments in the sources I read. They are different molecules with different safety records, so this page treats each separately. For the wider family see Ghrelin and Growth-Hormone Secretagogues. Evidence labels used: preclinical (cells/animals only), promising but limited, insufficient evidence, evidence of harm (where a regulator names harms), and marketing claim.Exact identities
A 1997 review described GHRP-6 as the first hexapeptide studied extensively in humans, with GHRP-2 and hexarelin synthesized later; the receptor was found to bind these peptides before ghrelin itself was identified. [1] Published sequences: GHRP-6 is His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, [2] and hexarelin is His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2. [3] I did not verify a sequence for GHRP-2 from a primary source, so none is given here. Products sold online under these names may not match the molecule in a paper (see Research Peptide Naming and Identity Problems).GHRP-2
Diagnostic use. In Japan, a GHRP-2 test is described as widely used to diagnose growth hormone deficiency. [4] A comparison in 71 adults with pituitary tumors found the GHRP-2 and arginine tests were acceptable alternatives to the insulin tolerance test in that population. [5] In 36 patients with hypothalamic-pituitary disorders, the ACTH response during the GHRP-2 test also helped flag secondary adrenal insufficiency. [4] These are single-dose testing uses supervised by specialists, not treatment.Longer-term use. In ten children with growth hormone deficiency given an oral form for 12 months, seven reported more appetite in the first six months, but body mass index did not change significantly. [6] Label: promising but limited for diagnosis; insufficient evidence for any treatment benefit.
GHRP-6
Pharmacology and testing. In nine healthy men, GHRP-6 showed a two-phase disappearance from blood with an elimination half-life of about 2.5 hours. [2] Combined with GHRH, it was part of a diagnostic test in 125 adults with pituitary disease versus 125 healthy people, with no side effects reported during testing. [7]Hormones beyond growth hormone. In healthy men, repeated GHRP-6 injections at night raised growth hormone, ACTH and cortisol and increased stage 2 sleep. [8] This is a reminder that these peptides are not selective for one hormone.
Animal findings. In rats with induced liver and gut injury, GHRP-6 reduced tissue damage markers. [9] Label: preclinical (cells/animals only). These findings are not evidence of human recovery or organ protection.
Hexarelin
In a rising-dose study, 12 healthy men received single hexarelin injections and growth hormone peaked at about 30 minutes. [3] Hexarelin also showed effects on the heart in short human studies. In people undergoing bypass surgery, one intravenous injection raised ejection fraction and cardiac output for up to 90 minutes, an effect not seen with GHRH or growth hormone. [10] In severe heart weakness from ischemic disease it raised ejection fraction acutely, but not in dilated cardiomyopathy. [11] These were small, single-dose, acute measurements. Label: promising but limited for hemodynamic markers; insufficient evidence for any lasting heart or health benefit.Who should be especially careful
Because these compounds affect cortisol, blood glucose and possibly heart function in the studies above, people with diabetes, heart disease or adrenal or pituitary conditions should discuss any exposure with their own clinician. [8][10] Pregnant or breastfeeding people and children have no safety data for non-diagnostic use in the sources read.Claims that exceed the evidence
Marketing for muscle gain, fat loss or recovery rests on growth hormone release. Higher growth hormone is a biomarker, not a clinical outcome; see Mechanisms vs Demonstrated Clinical Benefits. A 2026 review found many unapproved peptides help in animal models but rigorous human safety data are scarce. [15] See also Peptide Safety and Sports Anti-Doping Rules for Peptides.Frequently asked questions
Are GHRP-2, GHRP-6 and hexarelin the same thing?
No. They are three different synthetic peptides that act on the same receptor, with different sequences and different reported effects. [1]
Is GHRP-2 used as a medicine?
In Japan it is described as widely used as a diagnostic test for growth hormone deficiency. [4] That is not the same as an approved treatment, and I did not verify regulator status.
What has the FDA said about GHRP-2 and GHRP-6?
Both are in 503B compounding category 2, with listed safety concerns. [12]
Do they build muscle or burn fat?
Proper evidence not found. The human studies I read measured hormones, tests or short-term heart measures. [8][10]
Are they banned in sport?
Yes, all three types are named on the WADA 2026 list. [13]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and what regulators say
| Compound | Official statement read 2026-10-22 |
|---|---|
| GHRP-2 | FDA lists GHRP-2 for injectable and nasal use in compounding category 2 for 503B facilities (added 29 September 2023). It cites possible immune reactions, reports of serious adverse events including increased insulin requirement, death of critically ill study subjects, infection and pancreatitis, though causality has not been established. [12] |
| GHRP-6 | FDA lists GHRP-6 in 503B category 2 (added 29 September 2023), citing possible immune reactions, a potential effect on cortisol and higher blood glucose through reduced insulin sensitivity. [12] |
| Hexarelin | Not named in the FDA safety-risk list I read; FDA status otherwise not verified. |
| Sport | All three are named on the WADA 2026 Prohibited List (hexarelin as examorelin). [13] |
Category 2 means the FDA has identified significant safety risks and would consider taking action against a compounder under its general enforcement policies. [14] Other jurisdictions: not verified. This is not legal advice, and rules change.
References
- Ghigo E et al. Growth hormone-releasing peptides. Eur J Endocrinol 1997. PubMed 9186261. Read 2026-10-22.
- Cabrales A et al. Pharmacokinetic study of GHRP-6 in nine male healthy volunteers. Eur J Pharm Sci 2013. PubMed 23099431. Read 2026-10-22.
- Imbimbo BP et al. Growth hormone-releasing activity of hexarelin in humans. Eur J Clin Pharmacol 1994. PubMed 7957536. Read 2026-10-22.
- Suzuki S et al. Clinical usefulness of the GHRP-2 test for hypothalamic-pituitary disorder. J Endocr Soc 2022. PubMed 35795807. Read 2026-10-22.
- Kinoshita Y et al. The arginine and GHRP-2 tests as alternatives to the insulin tolerance test. Endocr J 2013. PubMed 23079545. Read 2026-10-22.
- Mericq V et al. Changes in appetite and body weight with oral GHRP-2 in GH-deficient children. J Pediatr Endocrinol Metab 2003. PubMed 14513874. Read 2026-10-22.
- Popovic V et al. GH-releasing hormone and GH-releasing peptide-6 for diagnostic testing in GH-deficient adults. Lancet 2000. PubMed 11030292. Read 2026-10-22.
- Frieboes RM et al. GHRP-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man. Neuroendocrinology 1995. PubMed 7617137. Read 2026-10-22.
- Cibrian D et al. Use of GHRP-6 for the prevention of multiple organ failure. Clin Sci 2006. PubMed 16417467. Read 2026-10-22.
- Broglio F et al. Effects of acute hexarelin administration on cardiac performance in patients with coronary artery disease during by-pass surgery. Eur J Pharmacol 2002. PubMed 12144941. Read 2026-10-22.
- Imazio M et al. GH-independent cardiotropic activities of hexarelin in patients with severe left ventricular dysfunction. Eur J Heart Fail 2002. PubMed 11959048. Read 2026-10-22.
- U.S. FDA. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (content current as of 22 April 2026). FDA. Read 2026-10-22.
- World Anti-Doping Agency. Prohibited List 2026 (in effect 1 January 2026). Prohibited List 2026 (in effect 1 January 2026). Read 2026-10-22.
- U.S. FDA. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act (content current as of 14 May 2026). FDA. Read 2026-10-22.
- Mendias CL, Awan TM. Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries and athletic performance. Sports Med 2026. PubMed 41966639. Read 2026-10-22.