Which is better, GHRP-2 or GHRP-6?
Both carry the human_observational grade and the same not_eligible US status, so the edge is narrow. GHRP-2 has a regulator approved diagnostic use outside the US and a validated adult diagnostic protocol (Chihara 2007), plus a controlled crossover quantifying its appetite effect; GHRP-6 has only small acute studies. Neither has a randomized trial of repeated therapeutic use, and FDA cited glucose, cortisol, and immunogenicity concerns for both. [3] [4] [7] [11]
How do GHRP-2 and GHRP-6 compare?
| Dimension | GHRP-2Favored | GHRP-6 |
|---|---|---|
| Origin and structure [5] [6] [11] | D-Ala-D-beta-Nal-Ala-Trp-D-Phe-Lys-NH2; contains the unnatural amino acid D-beta-naphthylalanine, which FDA noted complicates characterization. | His-D-Trp-Ala-Trp-D-Phe-Lys-NH2; the first GHRP, described in 1984 and the template for GHRP-2, hexarelin, and ipamorelin. |
| Best human evidence [1] [4] [7] [8] | Diagnostic validation: a 100 ug intravenous test with a peak GH cutoff of 9 ng/mL identified severe adult GH deficiency (62 patients plus controls). Pediatric dose response in 34 short children. | Acute studies only: four overnight 50 ug intravenous boluses raised GH, ACTH, cortisol, and stage 2 sleep in healthy men; oral 300 ug/kg released GH in short children. |
| Approved uses anywhere [4] [11] | Approved in Japan as pralmorelin, a diagnostic agent for GH deficiency. No therapeutic approval anywhere. | Never approved for any use in any country. |
| Appetite effect [3] [9] | A 1 ug/kg per hour infusion raised ad libitum food intake by 35.9% versus saline in a double blind crossover of 7 healthy men. | Marked hunger is its most consistently reported effect, but no controlled human food intake study is in the record. |
| Other hormonal effects [2] [7] [9] | Raises prolactin, ACTH, and cortisol alongside GH; in healthy adults it released more GH than GHRH. | Raises ACTH, cortisol, and prolactin; GH release is synergistic with GHRH. |
| Studied routes and doses [1] [4] [7] [8] | Intravenous 1 ug/kg (children) or 100 ug (adults) as a diagnostic bolus; intranasal in research. No chronic dose established. | Intravenous 1 ug/kg or 4 x 50 ug overnight; oral 300 ug/kg in children. No chronic dose established. |
| FDA Category 2 rationale [11] [12] [13] | 503B Category 2 (injectable and nasal routes) since September 29, 2023: immunogenicity, characterization problems from the unnatural amino acid, and reports of serious adverse events including pancreatitis in critically ill subjects. | 503B Category 2 since September 29, 2023: immunogenicity from aggregation and impurities, cortisol effects, and higher blood glucose from reduced insulin sensitivity. |
| Note: Neither has a 503A nomination or listing, so no licensed pharmacy can compound either. Both are prohibited under WADA section S2. | ||
Evidence grade and regulatory status
Pulled from each peptide’s own record, so it stays in step with the peptide pages.
| Attribute | GHRP-2 | GHRP-6 |
|---|---|---|
| Class | Synthetic hexapeptide growth hormone secretagogue (ghrelin receptor agonist) | Synthetic hexapeptide growth hormone secretagogue (ghrelin receptor agonist), the first of the GHRP series |
| What it is | Lab-made peptide that triggers growth hormone through the hunger hormone (ghrelin) receptor; approved only as a diagnostic test in Japan; WADA prohibited. | Original lab-made growth hormone releasing peptide: raises GH and hunger in small human studies; never approved; on an FDA compounding risk list; WADA banned. |
| Evidence | Evidence: Human observational evidence | Evidence: Human observational evidence |
| FDA status | Regulatory: Not eligible for compounding | Regulatory: Not eligible for compounding |
| Compounding | Not FDA approved for any use. FDA added GHRP-2 (for injectable and nasal routes) to the 503B Category 2 list on September 29, 2023, citing immunogenicity risk, an unnatural amino acid that complicates characterization, and reports of serious adverse events. As of the FDA page current to April 22, 2026, GHRP-2 remains in 503B Category 2 and has no 503A nomination or listing, so licensed compounding pharmacies have no lawful basis to compound it. It was not among the peptides withdrawn from Category 2 in April 2026. Pralmorelin is approved in Japan only as a diagnostic agent. | Not FDA approved for any use. FDA added GHRP-6 to the 503B Category 2 list on September 29, 2023, citing immunogenicity risk from aggregation and impurities, effects on cortisol, and increased blood glucose from reduced insulin sensitivity. As of the FDA page current to April 22, 2026, GHRP-6 remains in 503B Category 2 and has no 503A nomination, so no licensed pharmacy has a lawful basis to compound it. It was not among the peptides withdrawn from Category 2 in April 2026. |
| WADA | WADA: WADA prohibited | WADA: WADA prohibited |
| Routes | Intravenous bolus or infusion (diagnostic and research studies), Intranasal (research studies), Subcutaneous injection (as sold, not from published trials) | Intravenous bolus (research studies), Oral (one pediatric study), Subcutaneous injection (as sold, not from published trials) |
| Typical cost | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Last verified |
Has GHRP-2 been tested directly against GHRP-6?
No published trial has compared GHRP-2 and GHRP-6 directly. The dimensions above come from separate studies and labels, and cross-trial comparisons are less reliable than a direct trial.
What do GHRP-2 and GHRP-6 cost?
| Dimension | GHRP-2 | GHRP-6 |
|---|---|---|
| Typical cost | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. | Not available through licensed US channels. Products sold as research chemicals are not lawful for human use and are not verified for identity or purity. |
| Price detail | Price index in progress | Price index in progress |
Where a price index exists, the range is the cash price per month across branded, compounded, and telehealth channels, without insurance. The cost pages give each channel separately with its sources. Otherwise the typical cost from the peptide record is shown. Legal access depends on your state: see peptide legality by state.
Frequently asked questions
What is the difference between GHRP-2 and GHRP-6?
Both are six amino acid ghrelin receptor agonists. GHRP-6 was the first, described in 1984; GHRP-2 is a later analog that became a licensed diagnostic agent in Japan. Both raise GH, cortisol, and prolactin and increase appetite. [4] [5] [6] [9]
Which one makes you hungrier?
GHRP-6 is the one most associated with hunger in reviews of the class, but the only controlled human measurement is for GHRP-2, which raised food intake by 35.9% in healthy men. No trial has compared them directly. [3] [9]
Has either been approved as a medicine?
GHRP-2 is approved in Japan only as a diagnostic test for growth hormone deficiency. GHRP-6 has never been approved. Neither has an approved therapeutic use anywhere. [4] [11]
Can a US pharmacy compound GHRP-2 or GHRP-6?
No. FDA placed both in 503B Category 2 in September 2023 and neither has a 503A nomination or listing, so there is no lawful compounding pathway. Research chemical products are not lawful for human use. [11] [12]
Are they allowed in sport?
No. Both are growth hormone secretagogues prohibited at all times under WADA section S2, and anti-doping labs test for their urinary metabolites. [10] [13]
Sources
Numbered citations above point to these primary sources. PubMed entries link to the indexed abstract.
- [1]Pihoker C et al. Diagnostic studies with intravenous and intranasal growth hormone-releasing peptide-2 in children of short stature. J Clin Endocrinol Metab 1995PubMed 7559885, 1995
- [2]Arvat E et al. Effects of GHRP-2 and hexarelin on GH, prolactin, ACTH and cortisol levels in man. Peptides 1997PubMed 9285939, 1997
- [3]Laferrere B et al. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab 2005PubMed 15699539, 2005
- [4]Chihara K et al. A simple diagnostic test using GH-releasing peptide-2 in adult GH deficiency. Eur J Endocrinol 2007PubMed 17609397, 2007
- [5]Bowers CY. Growth hormone-releasing peptide (GHRP). Cell Mol Life Sci 1998PubMed 9893708, 1998
- [6]Bowers CY et al. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology 1984PubMed 6714155, 1984
- [7]Frieboes RM et al. Growth hormone-releasing peptide-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man. Neuroendocrinology 1995PubMed 7617137, 1995
- [8]Bellone J et al. Growth hormone-releasing effect of oral GHRP-6 administration in children with short stature. Eur J Endocrinol 1995PubMed 7581965, 1995
- [9]Camanni F, Ghigo E, Arvat E. Growth hormone-releasing peptides and their analogs. Front Neuroendocrinol 1998PubMed 9465289, 1998
- [10]Semenistaya E et al. Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, hexarelin, and ipamorelin. Drug Test Anal 2015PubMed 25869809, 2015
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<a href="https://peptideagent.ai/compare/ghrp-2-vs-ghrp-6">GHRP-2 vs GHRP-6: evidence, cost, and legality</a>, PeptideAgent, updated September 22, 2026.