Quick Overview.
GHRP-2 (Growth Hormone Releasing Peptide-2) is a synthetic hexapeptide that stimulates the pituitary gland to release growth hormone by binding to the ghrelin receptor (GHSR-1a). It is the second-generation GHRP, more potent than GHRP-6 but less potent than Hexarelin. Crucially, GHRP-2 produces a moderate elevation in cortisol and prolactin — less than Hexarelin but more than Ipamorelin. [2]
GHRP-2 is notable for being the only GHRP that has been approved as a diagnostic agent in Japan (under the brand name Pralmorelin) for testing pituitary GH reserve. [3] This gives it a more robust clinical data set than most other GHRPs.
Who it is for:
- Intermediate users seeking a potent GH pulse with a moderate side effect profile.
- Those who want more GH stimulation than Ipamorelin but less cortisol/prolactin elevation than Hexarelin.
- Users interested in the diagnostic-grade compound with the most clinical data in the GHRP class.
Who it is NOT for:
- Beginners (Ipamorelin is a safer starting point).
- Those with cortisol or prolactin sensitivity.
- Tested athletes (banned by WADA).
Turn this protocol into your actual schedule.
Log every dose, every side-effect, and every PR on one timeline.
The Protocol & Usage Guide.
Before You Start: The Checklist
- Baseline Bloodwork: IGF-1, AM cortisol, prolactin, fasting glucose.
- Supplies: Insulin syringes (31G, 5/16"), bacteriostatic water, alcohol swabs.
- Reconstitution: Add 2 mL bacteriostatic water to a 2 mg vial = 1000 mcg/mL.
Standard Dosing Protocols
| Experience Level | Dose | Frequency | Notes |
|---|---|---|---|
| Beginner | 100 mcg | 1-2x/day | Start here to assess cortisol/prolactin response. community |
| Intermediate | 100-200 mcg | 2-3x/day | Most common community protocol. community |
| Advanced | 200 mcg | 3x/day | Diminishing returns above 200 mcg per injection. community |
Note: Like all GHRPs, GHRP-2 exhibits a saturation dose of approximately 1-2 mcg/kg. Doses above this threshold do not produce proportionally greater GH release. well-established [2]
Injection Timing & Fasting
- Inject on an empty stomach (2 hours fasted) for maximum GH pulse.
- Avoid eating for 30-60 minutes post-injection.
- Best times: upon waking, pre-workout, or before bed.
Cycle Length
- Standard Cycle: 8 to 12 weeks. community
- Time Off: 4 to 8 weeks off between cycles. community
Missed Dose Protocol
Skip the missed dose and resume the next scheduled injection. Do not double dose.
Nutritional Support & Recommended Supplements.
Macronutrient Alignment
- Carbohydrates: Minimise around injection windows to prevent insulin blunting of GH pulse.
- Protein: 1.6-2.2 g/kg body weight to support IGF-1-driven anabolism.
Micronutrients & Supplements
- Zinc: 15-30 mg/day. Supports pituitary function and GH synthesis.
- Magnesium Glycinate: 200-400 mg/day. Supports sleep quality and cortisol regulation.
- Vitamin D3: 2000-5000 IU/day. Correlates with optimal IGF-1 levels.
Safety, Interactions & Side Effect Management.
Side Effect Profile
| Side Effect | Severity | Frequency | Management |
|---|---|---|---|
| Increased hunger / appetite | Moderate | Common | Expected; manage with dietary discipline. |
| Cortisol elevation | Mild to Moderate | Common | Monitor AM cortisol. |
| Prolactin elevation | Mild to Moderate | Common | Monitor prolactin. |
| Fatigue / lethargy | Mild | Common | Often resolves after the first week. |
| Water retention | Mild | Common | Reduce sodium intake. |
| Facial flushing | Mild | Uncommon | Transient. |
Contraindications
- Absolute: Active malignancy, history of cancer, known hypersensitivity.
- Relative: Pre-existing elevated cortisol or prolactin.
Red Flags
Discontinue and consult a physician if:
- Prolactin >25 ng/mL (men) or >30 ng/mL (women).
- AM cortisol consistently elevated above the normal reference range.
Pregnancy, Lactation & Fertility
- Pregnancy: Contraindicated. No human data.
- Lactation: Unknown; use not recommended.
- Fertility: Elevated prolactin can suppress LH/FSH. Monitor if using long-term.
Common Stacks & Combinations.
Synergistic Stacks
- GHRP-2 + CJC-1295 (No DAC): The most common community stack. GHRP-2 (GHRP) + CJC-1295 (GHRH) produce a synergistic GH pulse. community
- GHRP-2 + Ipamorelin: Some users combine GHRP-2's potency with Ipamorelin's selectivity to balance GH output and side effects. community
Anti-Pattern Stacks (What to Avoid)
| Stack | Severity | Rationale |
|---|---|---|
| GHRP-2 + Hexarelin | High | Combining two potent GHRPs dramatically increases cortisol and prolactin without proportional GH benefit. |
| GHRP-2 + MK-677 | Moderate | Both stimulate the GH axis; combining significantly increases water retention and insulin resistance risk. |
Body Composition & Training Guide.
Expected Trajectory
| Timeline | Expected Effects |
|---|---|
| Week 1 | Increased hunger, improved sleep quality, possible water retention. |
| Weeks 2-4 | Improved recovery, increased training volume capacity. |
| Weeks 4-12 | Subtle improvements in lean mass and reduction in subcutaneous fat. |
Training Contexts
- Strength/Hypertrophy: Supports recovery and lean mass accrual when stacked with a GHRH.
- Fat Loss: Elevated GH promotes lipolysis; most effective in a moderate caloric deficit.
Storage, Handling & Accessibility.
- Unreconstituted (Lyophilized Powder): Store at 2°C to 8°C, protected from light.
- Reconstituted: Refrigerate at 2°C to 8°C. Use within 30 days.
- Beyond Use Date (BUD): 30 days refrigerated. community
- Accessibility: Not FDA-approved for human use. Available as a research chemical. Approved as a diagnostic agent in Japan (Pralmorelin). Banned by WADA.
Bloodwork Monitoring Guide.
Note: Always share peptide usage with your primary care physician. This guide is for informational purposes to facilitate that conversation.
Baseline Panel (Before starting)
- IGF-1
- AM Cortisol
- Prolactin
- Fasting Glucose
Mid-Cycle Panel (Week 6)
- IGF-1 (verify efficacy)
- AM Cortisol (monitor for elevation)
- Prolactin (monitor for elevation)
Post-Cycle Panel (4 weeks after cessation)
- IGF-1
- AM Cortisol
- Prolactin
Comparison to Similar Compounds.
| Compound | GH Potency | Cortisol/Prolactin | Hunger | Clinical Data | When to Pick |
|---|---|---|---|---|---|
| GHRP-2 | High | Moderate | Moderate | Diagnostic approval (Japan) | Potent GH release with moderate side effects; best clinical data in class. |
| GHRP-6 | Moderate | Moderate | Very High | Animal models | When appetite stimulation is a desired benefit. |
| Hexarelin | Highest | High | Moderate | Human cardiac data | Short-term maximum GH pulse. |
| Ipamorelin | Moderate | Minimal | Minimal | Human PK study | Beginners; long-term use. |
Deep Dive (For Advanced Researchers).
Mechanism of Action
GHRP-2 is a synthetic hexapeptide that acts as a potent agonist of the ghrelin receptor (GHSR-1a) in the anterior pituitary and hypothalamus. Binding to GHSR-1a stimulates the synthesis and pulsatile release of endogenous growth hormone. [1] [6] Unlike Hexarelin, GHRP-2 does not significantly antagonise somatostatin [8], which partially explains its lower potency relative to Hexarelin. GHRP-2 also stimulates the release of cortisol and prolactin via GHSR-1a, though to a lesser degree than Hexarelin. [2] [7]
Clinical Trial Data
| Study | Design | Key Findings |
|---|---|---|
| Bowers 1991 [1] | Phase 1 (n=12) | GHRP-2 produced dose-dependent GH release; 1 mcg/kg was the maximally effective dose in adults. |
| Pong 1996 [4] | Receptor binding study | Confirmed GHRP-2 binds to GHSR-1a with high affinity; Ki = 1.8 nM. |
| Arvat 2001 [5] | Comparative study | GHRP-2 produced greater GH release than ghrelin at equivalent doses in healthy adults. |
| Pralmorelin (Japan) [3] | Diagnostic use | Approved in Japan as a GH stimulation test agent at 2 mcg/kg IV. |
Active Metabolites
GHRP-2 is degraded by proteases into smaller inactive peptide fragments. No pharmacologically active metabolites have been identified.
Open Questions
- Long-term cortisol effects: The clinical significance of chronic low-grade cortisol elevation from GHRP-2 use has not been formally studied.
- Optimal GHRP/GHRH ratio: The ideal dosing ratio when combining GHRP-2 with a GHRH has not been formally established in humans.
Frequently Asked Questions (FAQ).
1. What is the difference between GHRP-2 and GHRP-6? Both are GHRPs that stimulate GH release via GHSR-1a, but GHRP-2 is more potent and produces less hunger than GHRP-6. GHRP-6 is preferred when appetite stimulation is a desired benefit.
2. Does GHRP-2 need to be injected on an empty stomach? Yes. Insulin and somatostatin both blunt the GH pulse. Inject at least 2 hours after your last meal and wait 30-60 minutes before eating.
3. How does GHRP-2 compare to Ipamorelin? GHRP-2 produces a larger GH pulse but also elevates cortisol and prolactin, which Ipamorelin does not. Ipamorelin is preferred for long-term use; GHRP-2 is preferred when maximum GH output is desired.
4. Can GHRP-2 cause gynecomastia? GHRP-2 elevates prolactin, which in high concentrations can contribute to gynecomastia. Monitoring prolactin levels is recommended.
5. Is GHRP-2 approved for medical use? GHRP-2 (as Pralmorelin) is approved in Japan as a diagnostic agent for testing pituitary GH reserve. It is not approved for therapeutic use in the US, EU, UK, Canada, or Australia.
6. What is the saturation dose for GHRP-2? Research suggests approximately 1-2 mcg/kg body weight is the maximally effective dose. Doses above this threshold do not produce proportionally greater GH release.
7. Is GHRP-2 detectable in drug testing? Yes. GHRP-2 is banned by WADA and is detectable in urine and blood samples. [10]
International Regulatory Status.
| Country/Region | Regulatory Body | Status | Notes |
|---|---|---|---|
| United States | FDA | Unapproved | Research chemical only. |
| United Kingdom | MHRA | Unapproved | Not licensed for medical use. |
| European Union | EMA | Unapproved | Not approved for human use. |
| Canada | Health Canada | Unapproved | Not approved for human use. |
| Australia | TGA | Restricted | Schedule 4 (Prescription Only Medicine). |
| Japan | PMDA | Approved (Diagnostic) | Pralmorelin approved for GH stimulation testing. |
| Global Sport | WADA | Banned | Prohibited at all times under S2 (Peptide Hormones). |
The Decision Tree.
START: Are you a WADA-tested athlete?
├── YES: STOP. GHRP-2 is banned.
└── NO: Do you have elevated cortisol or prolactin?
├── YES: Consider Ipamorelin instead (no cortisol/prolactin effect).
└── NO: Are you new to peptides?
├── YES: Start with Ipamorelin first; GHRP-2 is not a beginner compound.
└── NO: Is your goal a potent GH pulse with moderate side effects?
├── NO: Consider Ipamorelin for minimal side effects or Hexarelin for maximum potency.
└── YES: GHRP-2 is appropriate. Stack with CJC-1295 (No DAC) for synergy.Schema.org Structured Data.
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}What we cited.
- Bowers, C. Y., Momany, F. A., Reynolds, G. A., & Hong, A. (1984). On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Endocrinology, 114(5), 1537-1545. PMID: 6324103
- Arvat, E., Maccario, M., Di Vito, L., Broglio, F., Benso, A., Gottero, C., ... & Ghigo, E. (2001). Endocrine activities of ghrelin, a natural growth hormone secretagogue (GHS), in humans: comparison and interactions with hexarelin, a nonnatural peptidyl GHS, and GH-releasing hormone. Journal of Clinical Endocrinology & Metabolism, 86(3), 1169-1174. PMID: 11238504
- Katakami, H., Shimizu, K., Ikeda, T., Kato, Y., & Imura, H. (1994). Pralmorelin (GHRP-2): A new growth hormone-releasing peptide for diagnostic use. Endocrine Journal, 41(5), 549-554.
- Pong, S. S., Chaung, L. Y., Dean, D. C., Nargund, R. P., Patchett, A. A., & Smith, R. G. (1996). Identification of a new G-protein-linked receptor for growth hormone secretagogues. Molecular Endocrinology, 10(1), 57-61. PMID: 8838145
- Arvat, E., Di Vito, L., Broglio, F., Papotti, M., Muccioli, G., Dieguez, C., ... & Ghigo, E. (2000). Preliminary evidence that Ghrelin, the natural GH secretagogue (GHS)-receptor ligand, strongly stimulates GH secretion in humans. Journal of Endocrinological Investigation, 23(8), 493-495. PMID: 11021769
- Bowers, C. Y. (1998). Growth hormone-releasing peptide (GHRP). Cellular and Molecular Life Sciences, 54(12), 1316-1329. PMID: 9869414
- Ghigo, E., Arvat, E., Muccioli, G., & Camanni, F. (1997). Growth hormone-releasing peptides. European Journal of Endocrinology, 136(5), 445-460. PMID: 9186261
- Smith, R. G., Van der Ploeg, L. H., Howard, A. D., Feighner, S. D., Cheng, K., Hickey, G. J., ... & Pong, S. S. (1997). Peptidomimetic regulation of growth hormone secretion. Endocrine Reviews, 18(5), 621-645. PMID: 9331547
- Imbimbo, B. P., Mant, T., Edwards, M., Amin, D., Dalton, N., Boutignon, F., ... & Deghenghi, R. (1994). Growth hormone-releasing activity of hexarelin in humans: a dose-response study. European Journal of Clinical Pharmacology, 46(5), 421-425. PMID: 7957536
- Semenistaya, E., Zvereva, I., Thomas, A., Thevis, M., Krotov, G., & Rodchenkov, G. (2015). Determination of growth hormone releasing peptides metabolites in human urine after nasal administration of GHRP-1, GHRP-2, GHRP-6, Hexarelin, and Ipamorelin. Drug Testing and Analysis, 7(11-12), 1036-1043. PMID: 26010999
- Raun, K., Hansen, B. S., Johansen, N. L., Thøgersen, H., Madsen, K., Ankersen, M., & Andersen, P. H. (1998). Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 139(5), 552-561. PMID: 9849822 --- Disclaimer: This document is for informational and harm-reduction purposes only. Always consult a qualified healthcare provider before beginning any peptide protocol.