GHRP-2 — Research Reference

GHRP-2 (Growth Hormone Releasing Peptide-2) is a synthetic hexapeptide that acts as an agonist at the growth hormone secretagogue receptor type 1a (GHS-R1a), commonly referred to as the ghrelin receptor. It stimulates the pulsatile release of growth hormone (GH) from the anterior pituitary. GHRP-2 is among the most potent members of the GHRP class and produces stronger GH pulses than Ipamorelin at equivalent doses, with a corresponding increase in off-target hormonal effects including cortisol and prolactin elevation.

Quick Reference

Overview

GHRP-2 was developed during research into the ghrelin receptor system and the pharmacology of growth hormone secretagogues. It belongs to the GHRP family alongside GHRP-6, Ipamorelin, and Hexarelin — all of which share the ghrelin receptor as their primary target but differ in selectivity, potency, and off-target hormonal effects.

At the receptor level, GHRP-2 binds GHS-R1a and activates Gαq/11 signalling, triggering IP3/DAG-mediated calcium release in pituitary somatotrophs and culminating in GH exocytosis. This mechanism is distinct from and complementary to the GHRH receptor pathway targeted by GHRH analogues such as CJC-1295 and Sermorelin. The two pathways can be co-activated for synergistic GH release.

GHRP-2’s clinical research history includes use as a diagnostic agent for GH reserve — the GH response to intravenous GHRP-2 has been investigated as a test of pituitary somatotroph function, analogous to the insulin tolerance test but without the hypoglycaemia.

Reported Protocols

Subcutaneous Administration

Subcutaneous injection is the most commonly reported route in research accounts. Commonly reported doses range from 100 mcg to 300 mcg per injection, administered 1–3 times daily.

• Standard protocol: 100–200 mcg per injection, administered 1–3 times daily. Common injection windows: upon waking, pre-workout, and/or immediately before sleep.
• Fasted state: Administration in a fasted state or at least 2 hours away from meals is commonly reported to maximise the GH response. Elevated blood glucose and insulin blunt the GH response to GHS-R1a stimulation.
• Cycle duration: Commonly reported cycles range from 8 to 16 weeks.

Combination With GHRH Analogues

GHRP-2 is frequently reported in combination with GHRH analogues such as CJC-1295 or Sermorelin. Because GHRP-2 acts via the ghrelin receptor and GHRH analogues act via the GHRH receptor, their combination produces a synergistic GH pulse. The combined approach is among the most commonly described GH axis research stacks.

The synergistic potential of GHRP-2 plus a GHRH analogue may produce a larger GH pulse than the Ipamorelin/GHRH combination at equivalent doses, due to GHRP-2’s greater intrinsic potency at GHS-R1a — though this comes with greater cortisol and prolactin elevation.

Reported Effects

Growth Hormone Release

Research has investigated GHRP-2 for its potential role in stimulating potent, acute GH pulses from pituitary somatotrophs. GHRP-2 produces GH pulses at the higher end of the GHRP class, with human studies confirming significant GH elevation following administration. Studies have also demonstrated an amplifying effect when GHRP-2 is combined with GHRH.

IGF-1 Elevation

Research has investigated GHRP-2 for its potential role in elevating serum IGF-1, the primary downstream mediator of GH’s anabolic effects. IGF-1 elevation is a commonly used biomarker to assess the biological activity of GH secretagogues over time.

Body Composition

Research has investigated GHRP-2 for its potential role in improving body composition via GH-mediated effects — including lean mass accrual and fat mobilisation. These effects are mediated downstream through elevated GH and IGF-1.

Cortisol and Prolactin Elevation

Unlike Ipamorelin — which is selective for GH and produces minimal off-target hormonal effects — GHRP-2 produces measurable cortisol and prolactin elevation in addition to GH release. This is a consistent finding across GHRP-2 human studies. Cortisol elevation is dose-dependent and transient, typically peaking 15–30 minutes post-injection. Research accounts note this as a meaningful distinction from Ipamorelin, particularly for research contexts where elevated cortisol is undesirable.

Appetite Stimulation

Research has investigated GHRP-2 for its potential role in appetite stimulation via ghrelin receptor activation. The appetite-stimulating effect is less pronounced with GHRP-2 than with GHRP-6 but is present and frequently noted in anecdotal accounts.

Gastric Motility

Research has investigated GHRP-2 for potential effects on gastric motility and gastroprotection via the ghrelin pathway. These properties have been reported in preclinical models.

Reported Side Effects

Reported side effects in research and anecdotal accounts include the following.

Cortisol concern: The cortisol elevation produced by GHRP-2 is a meaningful distinction from Ipamorelin. Researchers for whom elevated cortisol is a specific concern — for example, those with stress-related conditions or who are also monitoring HPA axis function — commonly report preferring Ipamorelin or GHRP-2 at lower doses.

Storage & Handling

Lyophilized Powder (Unreconstituted)

• Refrigerator (2–8°C): Preferred; reported stable for 12 months or more
• Room temperature: Short-term stability acceptable; refrigerator strongly preferred
• Freezer: Acceptable for long-term storage; avoid repeated freeze-thaw cycles
• Protect from light and moisture

Reconstituted Solution

• Refrigerator (2–8°C): Use within 4–6 weeks of reconstitution
• Do not freeze reconstituted GHRP-2
• Bacteriostatic water is the preferred diluent for multi-dose vials
• Discard if the solution becomes cloudy or shows particulate matter

See the Reconstitution Guide for step-by-step instructions.

Frequently Asked Questions

How does GHRP-2 compare to Ipamorelin? Both bind the ghrelin receptor (GHS-R1a) and stimulate GH release. GHRP-2 produces a larger GH pulse at equivalent doses but also produces meaningful cortisol and prolactin elevation. Ipamorelin is more selective, producing GH release with minimal effect on cortisol, prolactin, or ACTH — making it the preferred GHRP for research contexts where off-target hormonal impact is a concern. GHRP-2 may be selected when maximal GH pulse amplitude is the priority.

How does GHRP-2 compare to GHRP-6? Both are hexapeptides with similar potency at GHS-R1a. The primary distinction is appetite stimulation: GHRP-6 produces more pronounced appetite stimulation than GHRP-2 and is historically noted as causing hunger intense enough to be uncomfortable at higher doses. GHRP-2 is generally preferred over GHRP-6 when appetite stimulation is not a desired research outcome. Both produce cortisol and prolactin elevation.

Should GHRP-2 be taken on an empty stomach? Commonly reported protocols specify administration in a fasted state or at least 2 hours from meals. Elevated blood glucose and insulin suppress GH secretion, blunting the response to GHS-R1a stimulation. The magnitude of the attenuation depends on the degree of insulin elevation, and anecdotal research accounts consistently describe fasted administration as producing a more robust GH response.

Can GHRP-2 be combined with a GHRH analogue? Yes. GHRP-2 and GHRH analogues (CJC-1295, Sermorelin) act on distinct receptor pathways and produce synergistic GH release when combined. This combination is among the most frequently reported approaches in GH axis research. See the GHRPs class page and Growth Hormone Secretion mechanism.

Related Pages

Goals: Muscle Growth · Performance

Class: GHRPs — Growth Hormone Releasing Peptides

Comparisons: Ipamorelin vs GHRP-2

References & Further Reading

• Laferrère B, et al. (2005). Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases food intake in healthy men. Journal of Clinical Endocrinology & Metabolism, 90(2), 611–614. PubMed →
• Popovic V, et al. (1995). Hypersecretion of growth hormone after GHRP-6 administration in patients with Cushing’s disease. Acta Endocrinologica, 132(2), 168–172.
• Bowers CY, et al. (2004). Growth hormone-releasing peptide (His-d-Trp-Ala-Trp-d-Phe-Lys-NH2): a novel growth hormone-releasing agent. Endocrinology, in multiple investigations.
• Hataya Y, et al. (2001). A low dose of ghrelin stimulates growth hormone (GH) release synergistically with GH-releasing hormone in humans. Journal of Clinical Endocrinology & Metabolism, 86(9), 4552–4555. PubMed →