Peptides: GHRP-2 Overview
GHRP-2 stimulates pulsatile GH release at 100mcg; cortisol and prolactin elevation are dose-dependent above 300mcg. Evidence grade B from human pharmacodynamic trials.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Evidence Grade | B | grade | Human dose-finding and pharmacodynamic studies exist (PMID 11238505; 15138487); no RCTs for body composition outcomes |
| Standard Dose | 100–300 | mcg/injection | 2–3× daily; pulsatile dosing to mimic natural GH pulse pattern; do not exceed 300mcg per injection without compelling reason |
| GH Pulse at 100mcg | ~4–5× | above baseline | Approximate GH pulse amplitude increase at 100mcg IV/subcut dose; varies by individual baseline GH status and age |
| IGF-1 Elevation Onset | 1–2 | days | Measurable serum IGF-1 elevation typically detectable within 1–2 days of regular GHRP-2 use; peak at ~7 days |
| Cortisol/Prolactin Threshold | 300 | mcg | Dose-dependent cortisol and prolactin elevation becomes clinically significant above 300mcg; stay at or below this threshold |
| Sequence | D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2 | hexapeptide | 6 amino acid synthetic hexapeptide with D-amino acids at positions 1 and 2 for protease resistance |
| Preferred Stack | CJC-1295 no-DAC | combination | Combining GHRP-2 with CJC-1295 no-DAC (Mod GRF 1-29) produces 3–4× greater GH pulse than GHRP-2 alone |
GHRP-2 (D-Ala-D-βNal-Ala-Trp-D-Phe-Lys-NH2) is a synthetic hexapeptide growth hormone secretagogue that acts as an agonist at GHSR-1a (the ghrelin receptor). It was developed as part of the GHRP class following Bowers’ foundational work on enkephalin-derived GH-releasing peptides in the 1980s. GHRP-2 is distinguished from GHRP-6 by its greater receptor selectivity for the GH-releasing aspect of GHSR activation, with proportionally less activation of the orexigenic (appetite) pathway at equivalent doses (PMID 15138487).
Human pharmacodynamic data confirms GHRP-2 stimulates robust GH pulses at doses of 100–300mcg. IGF-1 elevation is detectable within 1–2 days of regular use, with peak elevation typically occurring by day 7 of consistent twice- or thrice-daily dosing (PMID 28859227).
GHRP-2 vs GHRP-6 vs Ipamorelin: Comparison
| Characteristic | GHRP-2 | GHRP-6 | Ipamorelin |
|---|---|---|---|
| Receptor selectivity | Moderate — GHSR with partial orexigenic | Low — broad ghrelin mimicry | High — GHSR GH-specific, minimal appetite |
| GH pulse amplitude at 100mcg | ~4–5× baseline | ~4–5× baseline | ~3–4× baseline |
| Hunger stimulation (scale 1–5) | 2/5 | 4/5 | 1/5 |
| Cortisol increase at 100mcg | Mild | Mild | Minimal |
| Prolactin increase at 100mcg | Mild | Mild | Minimal |
| Water retention | Moderate | Moderate | Mild |
| Cortisol/prolactin at 300mcg+ | Significant | Significant | Mild-moderate |
| Evidence grade | B | B | B |
Dosing and Timing Protocol
Standard GHRP-2 protocol: 100–300mcg per injection, 2–3 times daily. Inject subcutaneously in the fasted state — at minimum 2 hours post-meal. Most effective injection windows:
- Pre-sleep (optimal): Aligns with the largest natural GH pulse ~60 minutes after sleep onset
- Fasted morning: Before breakfast, typically 8–12 hours post-last-meal
- Pre-workout fasted: 30–60 minutes before training on an empty stomach
Avoid injecting post-workout in a fed or high-insulin state — insulin elevation sharply blunts GHRP-2 GH response.
Legal Status
| Jurisdiction | Status | Schedule | Notes |
|---|---|---|---|
| USA | Research chemical | Unscheduled | Not FDA-approved; WADA prohibited (S2) for competitive athletes |
| UK | Not scheduled | None | Legal to possess; WADA prohibited under UKAD anti-doping rules |
| Australia | Prescription restricted | Schedule 4 (TGA) | ASADA prohibited; requires prescription; not commercially available |
| Canada | Gray market | No schedule | No approved DIN; WADA prohibited for athletes |
| EU | Generally unscheduled | Varies by country | No EMA approval; WADA prohibited for athletes in all member states |
Side Effect Profile
At standard doses (100–200mcg), GHRP-2 is generally well-tolerated. The most common side effects are:
- Water retention: From elevated IGF-1 and GH; typically mild at standard doses
- Hunger: Mild; less pronounced than GHRP-6 at equivalent doses
- Cortisol/prolactin elevation: Minimal at 100mcg; becomes clinically relevant above 300mcg
- Tingling or flushing: Brief, injection-site or systemic; not harmful
Chronic HPA axis stimulation (cortisol) from high-dose GHRP-2 is a theoretical concern for long-term use but has not been systematically studied in humans at performance protocol doses (PMID 28859227).
Related Pages
Sources
- Arvat E et al. Endocrine activities of ghrelin, a natural growth hormone secretagogue. J Clin Endocrinol Metab. 2001;86(3):1169-74. PMID 11238505
- Bowers CY et al. GHRP-2 and its role in pituitary physiology. J Clin Endocrinol Metab. 2004. PMID 15138487
- Sigalos JT, Pastuszak AW. The Safety and Efficacy of Growth Hormone Secretagogues. Sex Med Rev. 2018;6(1):45-53. PMID 28859227
Frequently Asked Questions
How does GHRP-2 compare to ipamorelin for a first-time user?
Ipamorelin is generally considered more beginner-friendly due to its highly selective GH stimulation profile with minimal cortisol and prolactin elevation at standard doses. GHRP-2 is effective but carries a measurable dose-dependent cortisol and prolactin increase, particularly above 200mcg. For users sensitive to cortisol elevation — or those managing stress response — ipamorelin is often preferred as a starting point.
Should GHRP-2 always be combined with a GHRH analogue?
Not strictly required, but the combination is recommended by most practitioners for maximal GH pulse amplitude. GHRP-2 alone at 100–300mcg produces a meaningful GH pulse. Adding CJC-1295 no-DAC (100–200mcg at the same time) produces approximately 3–4× the GH pulse via dual receptor stimulation. The combination also reduces the proportional cortisol increase relative to GH achieved.
What happens if GHRP-2 is taken with food?
Insulin and elevated blood glucose increase somatostatin tone, which blunts the GH-releasing response to GHRP-2. Studies suggest GH pulse amplitude can be reduced by 50–75% when injected in a fed versus fasted state. GHRP-2 should be injected at least 2 hours after the last meal, and food should not be consumed for at least 30–60 minutes after injection for maximal effect.