GHRP-2 vs GHRP-6: Human Studies and FDA Status | Dose Track
App Library Tools Pricing Download
[GH peptides · Comparison]

GHRP-2 vs GHRP-6: how do they differ?

Human studies · Side effects · FDA status

Short answer: Both are six-amino-acid peptides that act on the ghrelin receptor and trigger growth hormone release.1 GHRP-6 was the first studied widely in people; GHRP-2 came later and was developed in Japan as a diagnostic test for GH deficiency.12 Neither is FDA approved, and FDA lists both as compounding safety risks.3 No study has compared them directly.

How do GHRP-2 and GHRP-6 compare side by side?

From published human studies, FDA compounding lists and the 2026 WADA List. Neither has a US label.
GHRP-2 (pralmorelin)GHRP-6
What it isSynthetic hexapeptide, described as a super-analog of GHRP-64Synthetic hexapeptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2)5
Medical useDeveloped as a diagnostic agent for GH deficiency in Japan; used as the GHRP-2 test in Japanese clinical studies26Studied as a one-off GH test given into a vein7
US statusNot approved. FDA 503B Category 2 since September 29, 2023 (injectable and nasal)3Not approved. FDA 503B Category 2 since September 29, 20233
Half-lifeNo published human figure in the sources we checkedAbout 2.5 hours after a single IV dose in nine healthy men5
Appetite7 healthy men ate 35.9% more at a buffet during an infusion under the skin vs saline8Not measured in the human studies cited here
Cortisol and prolactinRaised prolactin, ACTH and cortisol slightly in healthy adults4FDA cites possible effects on cortisol and blood sugar3
Repeated dosing100 mcg under the skin daily for 5 days: GH response fell from day 1 to day 5 and IGF-1 did not rise9No repeated-dose human study in the sources we checked
SportWADA S2.2.4 (named)10WADA S2.2.4 (named)10

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

How are they related?

GHRP-6 was the first growth hormone releasing peptide to be studied widely in people. GHRP-2 and hexarelin came later as six-amino-acid relatives, and all of them act on the receptor now known as the ghrelin receptor.1 A 1997 review notes that their GH release is strong after IV, under-the-skin, nasal and even oral dosing, and that it weakens partly with repeated use, more with continuous infusion than with intermittent doses.1

What have human studies measured?

  • GHRP-2 and appetite: in 7 lean healthy men, a 270-minute infusion under the skin raised GH and they ate 35.9% more at a buffet meal than on saline.8
  • GHRP-2 with daily shots: in 9 healthy young men given 100 mcg once a day for 5 days, peak GH fell from 83 to 51 mcg/L and IGF-1 did not rise.9
  • GHRP-6 as a test: given into a vein, the GH response was lower in GH deficiency than in healthy children, with a lot of overlap between groups.7
  • GHRP-6 half-life: about 2.5 hours after a single IV dose of 100 to 400 mcg/kg in nine healthy men.5

No study has compared the two directly. These are study protocols, not personalized advice; confirm any dosing with your prescriber.

What has FDA said about them?

FDA placed both in Category 2 for outsourcing facilities on September 29, 2023. For GHRP-2 it cites immune-reaction risk and reports of rising insulin needs, deaths of critically ill study subjects, infection and pancreatitis, though causality was not established. For GHRP-6 it cites limited safety data and possible effects on cortisol and blood sugar.3

More detail: the GHRP-2 and GHRP-6 guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
MK-677 vs GHRP-6: how do they differ?Daily pill vs short-acting peptide Ipamorelin vs MK-677: how do they differ?Injected peptide vs daily oral ghrelin mimetic Ipamorelin vs sermorelin: how do they differ?Ghrelin mimetic vs GHRH analog Tesamorelin vs ipamorelin: how do they differ?FDA-approved GHRH analog vs ghrelin mimic

Frequently asked questions

Are GHRP-2 and GHRP-6 the same?+
No, but they are close relatives: both are six-amino-acid peptides that act on the ghrelin receptor. GHRP-2 is described as a super-analog of GHRP-6.14
Does GHRP-2 increase appetite?+
In one study of 7 healthy men, an infusion of GHRP-2 led them to eat 35.9% more at a buffet than on saline.8
Are they FDA approved?+
No. FDA placed both in Category 2 for outsourcing facilities in September 2023, citing safety concerns.3
Are they allowed in sport?+
No. The 2026 WADA List names GHRP-2 (pralmorelin) and GHRP-6 under S2.2.4.10
Can I track GHRP-2 or GHRP-6 in Dose Track?+
Yes. Both are built in, with reconstitution math so each dose shows in syringe units, and reminders.

Sources

  1. Ghigo E, et al. Growth hormone-releasing peptides. Eur J Endocrinol. 1997;136:445-60.
  2. Pralmorelin: GHRP 2, GPA 748, KP-102 (drug profile). Drugs R D. 2004;5:236-9.
  3. FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (Category 2 and nominated-but-withdrawn lists). Updated April 2026.
  4. Arvat E, et al. Effects of GHRP-2 and hexarelin, two synthetic GH-releasing peptides, on GH, prolactin, ACTH and cortisol levels in man. Peptides. 1997;18:885-91.
  5. Cabrales A, et al. Pharmacokinetic study of growth hormone-releasing peptide 6 (GHRP-6) in nine male healthy volunteers. Eur J Pharm Sci. 2013;48:40-6.
  6. Teramoto S, et al. Assessment of anterior pituitary reserve capacity based on growth hormone response to growth hormone-releasing peptide-2 test in the elderly. Growth Horm IGF Res. 2023;71:101545.
  7. Pombo M, et al. Growth hormone releasing hexapeptide-6 (GHRP-6) test in the diagnosis of GH-deficiency. J Pediatr Endocrinol Metab. 1996;9 Suppl 3:333-8.
  8. Laferrère B, et al. Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. J Clin Endocrinol Metab. 2005;90:611-4.
  9. Nijland EA, et al. A 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. Eur J Endocrinol. 1998;139:395-401.
  10. World Anti-Doping Agency. The 2026 Prohibited List, in force January 1, 2026 (English text as published in the Dutch Treaty Series, Tractatenblad 2026, 25).

All compound comparisons · GHRP-2 guide · GHRP-6 guide · All compound guides · Peptide tracking in Dose Track