GHRP-6
Also known as: Growth Hormone Releasing Peptide 6, Growth Hormone Releasing Hexapeptide, GHRP6, SKF-110679
GHRP-6 is a synthetic hexapeptide growth hormone secretagogue and one of the first GHRPs discovered. It potently stimulates GH release through the ghrelin receptor and is notable for its strong appetite-stimulating effects, making it valuable for research in both GH physiology and metabolism.
GHRP-6 is a 873.01 Da research peptide. GHRP-6 is a synthetic hexapeptide growth hormone secretagogue and one of the first GHRPs discovered. It potently stimulates GH release through the ghrelin receptor and is notable for its strong appetite-stimulating effects, making it valuable for research in both GH physiology and metabolism.
Also called: Growth Hormone Releasing Peptide 6, Growth Hormone Releasing Hexapeptide, GHRP6
873.01
Molecular Weight
Daltons
3
Strong Evidence
benefits
5
Studies Cited
peer-reviewed
100-300
Typical Dose
mcg
Overview
GHRP-6 (Growth Hormone Releasing Peptide 6) is a synthetic hexapeptide that was among the earliest growth hormone secretagogues (GHS) developed. Discovered through systematic screening of modified met-enkephalin derivatives by Cyril Bowers in the 1980s, GHRP-6 was a key compound in the identification and characterization of the growth hormone secretagogue receptor (GHS-R1a), later identified as the ghrelin receptor. GHRP-6 stimulates strong growth hormone release from the anterior pituitary and is characterized by its pronounced appetite-stimulating (orexigenic) properties; significantly stronger than other GHRPs. This hunger effect is mediated through hypothalamic ghrelin receptor activation and has made GHRP-6 particularly relevant in metabolic and appetite regulation research. GHRP-6 also stimulates cortisol and prolactin release at higher doses, more so than GHRP-2 or Ipamorelin. Despite being an older compound, GHRP-6 remains widely used in research due to its well-characterized pharmacology and reliable GH-stimulating effects.
Key Takeaways: GHRP-6
- Strongest evidence supports GHRP-6 for potent gh secretion and appetite stimulation
- Research doses typically range from 100 to 300 mcg via subcutaneous injection
- 3 benefits with strong evidence, 2 moderate, 1 preliminary
- Half-life: Approximately 15-25 minutes
- 5 cited research studies in this guide
Mechanism of Action
GHRP-6 binds to the GHS-R1a (ghrelin receptor) on pituitary somatotrophs, triggering GH release through activation of the phospholipase C/inositol trisphosphate (PLC/IP3) pathway and subsequent intracellular calcium mobilization. Unlike GHRH which acts through the cAMP/PKA pathway, GHRP-6 uses a distinct signaling cascade, explaining the amplified response when both receptor types are activated simultaneously. At the hypothalamic level, GHRP-6 stimulates GHRH release from arcuate nucleus neurons and functionally antagonizes somatostatin's inhibitory tone, amplifying GH secretion through dual mechanisms. GHRP-6 is a potent activator of appetite through central ghrelin receptor stimulation in the hypothalamus, particularly in the arcuate nucleus and ventromedial hypothalamus — where it activates NPY/AgRP neurons to drive hunger signaling. This orexigenic effect is markedly stronger than other GHRPs and can occur within minutes of administration. GHRP-6 also stimulates ACTH and cortisol release through hypothalamic CRH activation, and increases prolactin through non-dopaminergic pathways. These off-target hormonal effects are more pronounced than with GHRP-2 or Ipamorelin.
Research Benefits
GHRP-6 at a Glance
GHRP-6 binds to the GHS-R1a (ghrelin receptor) on pituitary somatotrophs, triggering GH release through activation of the phospholipase C/inositol trisphosphate (PLC/IP3) pathway and subsequent intracellular calcium mobilization.
Potent GH Secretion
Strong EvidenceStrongly stimulates growth hormone release from the pituitary, with well-documented dose-response curves. Established as a reliable GH secretagogue in hundreds of published studies across multiple decades.
Appetite Stimulation
Strong EvidenceProduces significant hunger through central ghrelin receptor activation. Useful in research contexts where appetite stimulation is desirable, such as cachexia, wasting, or underweight conditions.
Synergy with GHRH Analogs
Strong EvidenceLike other GHRPs, produces amplified GH release when combined with GHRH or GHRH analogs. The combined GH pulse exceeds either agent alone due to activation of distinct signaling pathways.
Cytoprotective Properties
Moderate EvidenceResearch suggests GHRP-6 has cardioprotective and gastroprotective effects mediated through ghrelin receptor activation in peripheral tissues, independent of GH release.
Body Composition
Moderate EvidenceThrough sustained GH elevation, research demonstrates potential improvements in lean mass, reduced adiposity, and enhanced connective tissue repair.
Gastric Motility
PreliminaryGHRP-6 enhances gastric motility and emptying through ghrelin receptor activation in the GI tract, which has been studied in post-operative ileus and gastroparesis models.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Standard GH stimulation protocol | 100–300 mcg | Subcutaneous injection |
| Saturation dose | 100–150 mcg | Subcutaneous injection |
| Appetite stimulation research | 100–200 mcg | Subcutaneous injection |
Frequency
1-3 times daily
Timing
Fasted state required, food significantly blunts GH response. Pre-bed and morning doses most common.
Cycle Length
8-16 weeks; periodic breaks recommended
Research Notes
- 1Expect significant hunger within 15-20 minutes of injection; this is a hallmark effect of GHRP-6.
- 2GH release is severely blunted by recent food intake, particularly fats and carbs.
- 3Saturation dose is approximately 100-150 mcg; higher doses increase side effects more than GH release.
- 4Cortisol and prolactin elevation is more pronounced with GHRP-6 than GHRP-2 or Ipamorelin.
- 5Often combined with GHRH analogs for enhanced GH release.
- 6The appetite effect can be used advantageously in wasting/cachexia research or when caloric intake needs to increase.
Reconstitution Guide
Standard Reconstitution
Vial Size
5 mg
Bacteriostatic Water
2 mL
Concentration
25 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
GHRP-6 vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 2 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at Refrigerated (2-8°C / 36-46°F) after reconstitution. Up to 30 days refrigerated after reconstitution.
Storage Temperature
Refrigerated (2-8°C / 36-46°F) after reconstitution
Shelf Life
Up to 30 days refrigerated after reconstitution
Important Notes
- •Use bacteriostatic water for reconstitution.
- •Store lyophilized powder frozen (-20°C) for long-term storage.
- •Swirl gently; never shake.
- •Solution should be clear and colorless.
GHRP-6 Dosing Calculator
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GHRP-6 Reconstitution Calculator
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Safety & Side Effects
Reported Side Effects
- !Intense hunger/appetite stimulation (primary and most notable side effect)
- !Cortisol elevation (more pronounced than GHRP-2 or Ipamorelin, dose-dependent)
- !Prolactin increase (transient, dose-dependent)
- !Water retention (from GH elevation)
- !Tingling/numbness in extremities (paresthesia)
- !Light-headedness or head rush immediately after injection
- !Injection site irritation
- !Potential for elevated blood glucose with chronic high-dose use
Potential Interactions
- ⚡complementary with GHRH analogs (CJC-1295, Sermorelin, Mod GRF 1-29).
- ⚡GH release is blunted by somatostatin analogs.
- ⚡Potential interaction with insulin — GH opposes insulin action.
- ⚡May interact with glucocorticoids which suppress GH.
- ⚡The appetite effect may interact with appetite suppressants or GLP-1 agonists.
- ⚡Cortisol elevation may be relevant for patients on corticosteroid therapy.
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone
Original characterization of GHRP-6 as a potent, specific GH secretagogue, establishing the foundation for the entire GHRP field and eventually leading to the discovery of the ghrelin receptor.
GHS-R1a; ghrelin receptor, mediates the cardioprotective effects of GHRP-6
Demonstrated that GHRP-6 provides direct cardioprotection in ischemia-reperfusion injury models, mediated through myocardial ghrelin receptor activation independent of GH release.
Growth hormone-releasing peptide-6 enhances gastric emptying
Showed GHRP-6 significantly accelerates gastric emptying in human subjects through ghrelin receptor activation in the GI tract, relevant to gastroparesis research.
GHRP-6 signal transduction pathways and GH release
Elucidated the PLC/IP3 signaling cascade activated by GHRP-6, distinguishing it from the cAMP pathway used by GHRH and explaining the amplified GH release when both pathways are activated.
GHRP-6 stimulates appetite and food intake through NPY pathways
Characterized the appetite-stimulating mechanism of GHRP-6 through hypothalamic NPY/AgRP neuron activation, explaining its potent orexigenic effects relative to other GHRPs.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
GHRP-6 is a synthetic growth hormone releasing peptide that stimulates GH secretion through the ghrelin receptor. It was one of the first GHRPs discovered and is known for its potent GH release and significant appetite-stimulating properties.
GHRP-6 activates ghrelin receptors in the hypothalamus, specifically stimulating NPY/AgRP neurons that drive hunger signaling. This is the same pathway activated by the body's natural hunger hormone, ghrelin. The effect is rapid, typically occurring within 15-20 minutes of injection.
Neither is objectively better — they have different profiles. GHRP-2 is generally considered to have a cleaner GH release (less cortisol, less appetite stimulation). GHRP-6 has stronger appetite stimulation (useful when increased food intake is desired) but more off-target hormonal effects. Choice depends on research objectives.
Yes, more so than other GHRPs. GHRP-6 produces a dose-dependent, transient cortisol elevation through hypothalamic CRH activation. At standard saturation doses (100-150 mcg), the elevation is modest and short-lived. Ipamorelin is preferred when cortisol elevation is a concern.
No. GH release from GHRP-6 is significantly blunted by food, especially fats and carbohydrates. Dose on an empty stomach, at least 30 minutes before eating or 2+ hours after a meal. The intense hunger from GHRP-6 makes the fasting requirement challenging for some individuals.
Approximately 100-150 mcg per injection (or ~1 mcg/kg body weight). Above this dose, GH release plateaus but side effects (cortisol, prolactin, hunger) continue to increase. Multiple daily doses at the saturation level are more effective than single larger doses.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.