Mechanism

How it works

GHRP-3 binds to the growth hormone secretagogue receptor type 1a (GHS-R1a), a G-protein coupled receptor expressed predominantly in the hypothalamus and pituitary gland, triggering intracellular signaling cascades involving phospholipase C, IP3, and intracellular calcium mobilization that promote somatotroph cell GH release. It also acts at the hypothalamic level to suppress somatostatin (growth hormone inhibiting hormone) tone and amplify GHRH-mediated signaling, resulting in synergistic GH pulse augmentation. Unlike ghrelin itself, GHRP-3 is more selective for GH release with comparatively reduced effects on appetite and cortisol stimulation relative to earlier-generation GHRPs.

Reported in research

Benefits

Stimulates pulsatile growth hormone release from the anterior pituitary
May support lean muscle mass accretion and body composition improvements
Potential enhancement of recovery speed from physical stress and tissue repair
Reported reduction in visceral and subcutaneous fat via GH-mediated lipolysis

Context, not a prescription

Dosing

Typical range: 100-300 mcg per injection, 1-3 times daily (Subcutaneous, Intramuscular)
Cycle length: 8-12 weeks
Half-life: ~15-20 minutes (active pulse duration ~2-3 hours)

Safety

Side effects & contraindications

Possible side effects

Transient injection site redness or discomfort
Mild increase in appetite (less pronounced than GHRP-6)
Elevated cortisol and prolactin levels with higher doses
Water retention due to IGF-1 elevation
Tingling or numbness in extremities (carpal tunnel-like symptoms)
Transient fatigue or lethargy post-injection

Contraindications

Active or history of hormone-sensitive cancers (GH can stimulate tumor growth)
Diabetic retinopathy or poorly controlled diabetes mellitus
Pregnancy or breastfeeding
Known hypersensitivity to GHRPs or peptide excipients
Active acromegaly or pituitary hyperfunction

Research information, not medical advice. Always consult a licensed clinician before considering any peptide.

In depth

Full profile

What it does

Users commonly report improved sleep quality, faster muscle recovery after workouts, gradual increases in lean muscle mass, and some reduction in body fat over several weeks. Mild water retention is common early on.

How it works

Imagine your pituitary gland is a vending machine that dispenses growth hormone. Normally, only your body's natural signals can press the button. GHRP-3 is like a key that lets you press that button extra times, getting more growth hormone out without having to inject GH directly.

After injection, GHRP-3 is quickly absorbed into the bloodstream and travels to the pituitary gland and hypothalamus. Within minutes it triggers a pulse of growth hormone release. This GH then signals the liver to produce IGF-1, which drives most of the muscle-building and fat-burning effects you feel over the following hours.

What to expect

GH pulse occurs within 15-30 minutes of injection. Physical effects like improved sleep quality and minor body composition changes may be noticed within 2-4 weeks of consistent use.

Week 1: Adjustment phase. GH pulses are occurring with each injection. You may notice improved sleep depth and mild water retention. Appetite may increase slightly around injection time.
Weeks 2-4: IGF-1 levels begin to rise. Recovery from training may feel noticeably faster. Sleep quality often improves. Some users report a subtle improvement in skin texture and mood.
Weeks 4-8: Body composition changes become more visible — modest lean muscle gain alongside gradual fat reduction, particularly around the midsection. Strength gains in the gym may become apparent. Continue monitoring blood markers.

Good to know

Always start at the lowest effective dose (100 mcg) and assess tolerance before increasing
Inject on an empty stomach (at least 1.5-2 hours after eating) to maximize GH pulse and reduce appetite side effects
Get baseline blood work including IGF-1, fasting glucose, and cortisol before starting
Cycle off periodically to prevent pituitary desensitization

Staying safe

Mild hunger increase shortly after injection
Slight soreness or redness at the injection site
Occasional water retention (puffy feeling)
Brief tiredness or grogginess after injecting

Avoid if you have:

People with any history of cancer, especially hormone-sensitive tumors
Pregnant or breastfeeding individuals
People with uncontrolled diabetes
Anyone under 21 years old (still developing)

Overview

Sustained multi-week protocols in preclinical models demonstrate increased lean body mass, reduced adipose tissue (particularly visceral), enhanced collagen synthesis, improved nitrogen retention, accelerated wound healing, and favorable shifts in lipid profiles (reduced LDL, increased HDL). Endogenous IGF-1 elevation mediates most anabolic effects via PI3K/AKT/mTOR signaling in skeletal muscle and PI3K/AKT-mediated anti-apoptotic signaling in multiple tissue types. GH-mediated lipolysis occurs via HSL (hormone-sensitive lipase) activation and adipocyte beta-adrenergic sensitization.

How it works

GHS-R1a functions like a phospholipase C-gated lock on somatotroph cells. GHRP-3 is a master key that fits this lock more cleanly than endogenous ghrelin in the pituitary context, opening intracellular calcium floodgates and launching a synchronized exocytotic event — while simultaneously silencing the somatostatin alarm system at the hypothalamic level, allowing the GH pulse to proceed unimpeded and at higher amplitude.

Following subcutaneous or intramuscular administration, GHRP-3 has a very short plasma half-life (~15-20 minutes) due to rapid proteolytic degradation. Despite this, it generates a GH pulse lasting approximately 90-180 minutes. Peak GH concentrations typically occur 15-30 minutes post-injection. Elevated GH stimulates hepatic IGF-1 synthesis over 4-8 hours. Chronic administration (weeks to months) leads to sustained elevation of mean 24-hour GH and IGF-1 levels, driving downstream anabolic, lipolytic, and tissue-repair pathways. Importantly, GHRP-3 preserves the pulsatile physiological pattern of GH secretion rather than producing the supraphysiological continuous elevation seen with exogenous recombinant GH.

Onset & timeline

GH plasma concentration peaks 15-30 minutes post-injection with an injection-to-peak pharmacokinetic profile consistent across GHRP class compounds. IGF-1 elevation lags by approximately 6-12 hours and requires 1-3 weeks of repeated dosing to show statistically significant mean elevation above baseline in animal models. Cortisol and prolactin co-stimulation peaks concurrently with GH, typically returning to baseline within 60-90 minutes.

Days 1-3: GHS-R1a engagement produces measurable GH pulses within 30 minutes of each injection (confirmed in analogous peptide studies). Acute pharmacodynamic effects include transient hyperglycemia and cortisol elevation. Plasma half-life of ~15-20 minutes; no meaningful accumulation between doses. Users may notice mild injection site reactions and post-injection somnolence from GH pulse.
Weeks 1-2: Cumulative IGF-1 elevation becomes measurable above baseline in sustained dosing protocols. Nitrogen retention improves with positive protein balance in skeletal muscle. Sleep architecture shifts — increased slow-wave (stage 3) sleep correlates with nocturnal GH pulse augmentation. Early improvements in recovery from exercise-induced muscle damage are reported.
Weeks 2-8: Progressive lean body mass accrual alongside measurable reduction in fat mass, particularly visceral adipose tissue. Collagen synthesis upregulation may improve connective tissue quality and joint resilience. IGF-1 levels plateau at a new elevated mean. Lipid panel improvements and enhanced glucose disposal (compensatory to GH insulin resistance) may be evident on bloodwork. Long-term beyond 8-12 weeks carries theoretical risk of receptor desensitization and requires cycling.

Getting the most from it

Monitor IGF-1 levels every 4-6 weeks during a cycle; target IGF-1 within the upper quartile of age-adjusted normal range, not supraphysiological levels
Implement a cyclic dosing protocol (e.g., 5 days on, 2 days off, or 8 weeks on, 4 weeks off) to minimize GHS-R1a desensitization
Administer injections in a fasted state (1.5-2 hours post-meal minimum) to avoid blunting of GH pulse by insulin and somatostatin co-stimulation
Consider pairing with a GHRH analogue (e.g., Mod-GRF 1-29/CJC-1295 no-DAC) to synergistically amplify GH pulse amplitude through complementary receptor pathways

Common side effects

Transient hypercortisolemia and hyperprolactinemia at doses above 200 mcg — may impair sleep architecture and immune function with chronic elevation
Dose-dependent fluid retention secondary to IGF-1-mediated renal sodium retention — typically resolves within days of dose reduction
Mild post-injection insulin resistance window (30-90 min post-dose) due to GH-mediated counter-regulatory glucose effects — avoid carbohydrate intake around injection time

Mechanism of action

GHRP-3 is a synthetic hexapeptide that functions as a full agonist at the growth hormone secretagogue receptor 1a (GHS-R1a), a Gαq/11-coupled GPCR. Receptor activation leads to phospholipase C-beta stimulation, generating IP3 and DAG, which together mobilize intracellular calcium from the endoplasmic reticulum and activate PKC, culminating in exocytosis of GH-containing secretory granules from anterior pituitary somatotrophs. Simultaneously, GHRP-3 acts at hypothalamic GHS-R1a to suppress somatostatinergic tone (SST14/SST28), reducing inhibitory brake on GH secretion, and may potentiate GHRH neuron activity, creating a synergistic amplification of the GH pulse amplitude. GHRP-3's modified peptide backbone compared to GHRP-6 (substitution of specific aromatic residues) confers somewhat reduced affinity for ghrelin-associated appetite circuits in the arcuate nucleus and vagal afferents, explaining its comparatively attenuated orexigenic profile.

Following subcutaneous or intramuscular administration, GHRP-3 has a very short plasma half-life (~15-20 minutes) due to rapid proteolytic degradation. Despite this, it generates a GH pulse lasting approximately 90-180 minutes. Peak GH concentrations typically occur 15-30 minutes post-injection. Elevated GH stimulates hepatic IGF-1 synthesis over 4-8 hours. Chronic administration (weeks to months) leads to sustained elevation of mean 24-hour GH and IGF-1 levels, driving downstream anabolic, lipolytic, and tissue-repair pathways. Importantly, GHRP-3 preserves the pulsatile physiological pattern of GH secretion rather than producing the supraphysiological continuous elevation seen with exogenous recombinant GH.

Pharmacodynamics

GH plasma concentration peaks 15-30 minutes post-injection with an injection-to-peak pharmacokinetic profile consistent across GHRP class compounds. IGF-1 elevation lags by approximately 6-12 hours and requires 1-3 weeks of repeated dosing to show statistically significant mean elevation above baseline in animal models. Cortisol and prolactin co-stimulation peaks concurrently with GH, typically returning to baseline within 60-90 minutes.

Sustained multi-week protocols in preclinical models demonstrate increased lean body mass, reduced adipose tissue (particularly visceral), enhanced collagen synthesis, improved nitrogen retention, accelerated wound healing, and favorable shifts in lipid profiles (reduced LDL, increased HDL). Endogenous IGF-1 elevation mediates most anabolic effects via PI3K/AKT/mTOR signaling in skeletal muscle and PI3K/AKT-mediated anti-apoptotic signaling in multiple tissue types. GH-mediated lipolysis occurs via HSL (hormone-sensitive lipase) activation and adipocyte beta-adrenergic sensitization.

Timeline

Days 1-3: GHS-R1a engagement produces measurable GH pulses within 30 minutes of each injection (confirmed in analogous peptide studies). Acute pharmacodynamic effects include transient hyperglycemia and cortisol elevation. Plasma half-life of ~15-20 minutes; no meaningful accumulation between doses. Users may notice mild injection site reactions and post-injection somnolence from GH pulse.
Weeks 1-2: Cumulative IGF-1 elevation becomes measurable above baseline in sustained dosing protocols. Nitrogen retention improves with positive protein balance in skeletal muscle. Sleep architecture shifts — increased slow-wave (stage 3) sleep correlates with nocturnal GH pulse augmentation. Early improvements in recovery from exercise-induced muscle damage are reported.
Weeks 2-8: Progressive lean body mass accrual alongside measurable reduction in fat mass, particularly visceral adipose tissue. Collagen synthesis upregulation may improve connective tissue quality and joint resilience. IGF-1 levels plateau at a new elevated mean. Lipid panel improvements and enhanced glucose disposal (compensatory to GH insulin resistance) may be evident on bloodwork. Long-term beyond 8-12 weeks carries theoretical risk of receptor desensitization and requires cycling.

Comparisons

GHRP-3 — effectiveness Moderate, safety Moderate, cost $$, Medium to use
GHRP-2 — effectiveness High, safety Moderate, cost $$, Medium to use
Ipamorelin — effectiveness Moderate, safety Good, cost $$, Medium to use
Tesamorelin — effectiveness High, safety Good, cost $$$$, Medium to use

Adverse effects

Common:

Transient hypercortisolemia and hyperprolactinemia at doses above 200 mcg — may impair sleep architecture and immune function with chronic elevation
Dose-dependent fluid retention secondary to IGF-1-mediated renal sodium retention — typically resolves within days of dose reduction
Mild post-injection insulin resistance window (30-90 min post-dose) due to GH-mediated counter-regulatory glucose effects — avoid carbohydrate intake around injection time

Rare:

Carpal tunnel syndrome-like symptoms (median nerve compression from fluid retention) — incidence estimated <5% at standard doses in analogous GHRP class compounds
Pituitary desensitization with chronic high-frequency dosing (>3x/day for extended periods) — theoretical based on receptor downregulation data from animal studies

Contraindications & risk mitigation

Contraindicated in:

Patients with IGF-1-sensitive malignancies (breast, prostate, colorectal cancer) — GH/IGF-1 axis upregulation may accelerate tumor proliferation via IGF-1R signaling
Individuals with active acromegaly, pituitary adenomas, or documented pituitary hyperfunction
Type 1 or poorly controlled Type 2 diabetics — GH-mediated insulin resistance may significantly worsen glycemic control
Patients on glucocorticoid therapy — may blunt GH pulse amplitude and confound cortisol monitoring

Monitor IGF-1 levels every 4-6 weeks during a cycle; target IGF-1 within the upper quartile of age-adjusted normal range, not supraphysiological levels
Implement a cyclic dosing protocol (e.g., 5 days on, 2 days off, or 8 weeks on, 4 weeks off) to minimize GHS-R1a desensitization
Administer injections in a fasted state (1.5-2 hours post-meal minimum) to avoid blunting of GH pulse by insulin and somatostatin co-stimulation
Consider pairing with a GHRH analogue (e.g., Mod-GRF 1-29/CJC-1295 no-DAC) to synergistically amplify GH pulse amplitude through complementary receptor pathways

Qué hace

Users commonly report improved sleep quality, faster muscle recovery after workouts, gradual increases in lean muscle mass, and some reduction in body fat over several weeks. Mild water retention is common early on.

Cómo funciona

Imagine your pituitary gland is a vending machine that dispenses growth hormone. Normally, only your body's natural signals can press the button. GHRP-3 is like a key that lets you press that button extra times, getting more growth hormone out without having to inject GH directly.

After injection, GHRP-3 is quickly absorbed into the bloodstream and travels to the pituitary gland and hypothalamus. Within minutes it triggers a pulse of growth hormone release. This GH then signals the liver to produce IGF-1, which drives most of the muscle-building and fat-burning effects you feel over the following hours.

Qué esperar

GH pulse occurs within 15-30 minutes of injection. Physical effects like improved sleep quality and minor body composition changes may be noticed within 2-4 weeks of consistent use.

Week 1: Adjustment phase. GH pulses are occurring with each injection. You may notice improved sleep depth and mild water retention. Appetite may increase slightly around injection time.
Weeks 2-4: IGF-1 levels begin to rise. Recovery from training may feel noticeably faster. Sleep quality often improves. Some users report a subtle improvement in skin texture and mood.
Weeks 4-8: Body composition changes become more visible — modest lean muscle gain alongside gradual fat reduction, particularly around the midsection. Strength gains in the gym may become apparent. Continue monitoring blood markers.

Bueno saber

Always start at the lowest effective dose (100 mcg) and assess tolerance before increasing
Inject on an empty stomach (at least 1.5-2 hours after eating) to maximize GH pulse and reduce appetite side effects
Get baseline blood work including IGF-1, fasting glucose, and cortisol before starting
Cycle off periodically to prevent pituitary desensitization

Manteniéndose seguro

Mild hunger increase shortly after injection
Slight soreness or redness at the injection site
Occasional water retention (puffy feeling)
Brief tiredness or grogginess after injecting

Evitar si tienes:

People with any history of cancer, especially hormone-sensitive tumors
Pregnant or breastfeeding individuals
People with uncontrolled diabetes
Anyone under 21 years old (still developing)

Descripción general

Sustained multi-week protocols in preclinical models demonstrate increased lean body mass, reduced adipose tissue (particularly visceral), enhanced collagen synthesis, improved nitrogen retention, accelerated wound healing, and favorable shifts in lipid profiles (reduced LDL, increased HDL). Endogenous IGF-1 elevation mediates most anabolic effects via PI3K/AKT/mTOR signaling in skeletal muscle and PI3K/AKT-mediated anti-apoptotic signaling in multiple tissue types. GH-mediated lipolysis occurs via HSL (hormone-sensitive lipase) activation and adipocyte beta-adrenergic sensitization.

Cómo funciona

GHS-R1a functions like a phospholipase C-gated lock on somatotroph cells. GHRP-3 is a master key that fits this lock more cleanly than endogenous ghrelin in the pituitary context, opening intracellular calcium floodgates and launching a synchronized exocytotic event — while simultaneously silencing the somatostatin alarm system at the hypothalamic level, allowing the GH pulse to proceed unimpeded and at higher amplitude.

Following subcutaneous or intramuscular administration, GHRP-3 has a very short plasma half-life (~15-20 minutes) due to rapid proteolytic degradation. Despite this, it generates a GH pulse lasting approximately 90-180 minutes. Peak GH concentrations typically occur 15-30 minutes post-injection. Elevated GH stimulates hepatic IGF-1 synthesis over 4-8 hours. Chronic administration (weeks to months) leads to sustained elevation of mean 24-hour GH and IGF-1 levels, driving downstream anabolic, lipolytic, and tissue-repair pathways. Importantly, GHRP-3 preserves the pulsatile physiological pattern of GH secretion rather than producing the supraphysiological continuous elevation seen with exogenous recombinant GH.

Inicio y cronología

GH plasma concentration peaks 15-30 minutes post-injection with an injection-to-peak pharmacokinetic profile consistent across GHRP class compounds. IGF-1 elevation lags by approximately 6-12 hours and requires 1-3 weeks of repeated dosing to show statistically significant mean elevation above baseline in animal models. Cortisol and prolactin co-stimulation peaks concurrently with GH, typically returning to baseline within 60-90 minutes.

Days 1-3: GHS-R1a engagement produces measurable GH pulses within 30 minutes of each injection (confirmed in analogous peptide studies). Acute pharmacodynamic effects include transient hyperglycemia and cortisol elevation. Plasma half-life of ~15-20 minutes; no meaningful accumulation between doses. Users may notice mild injection site reactions and post-injection somnolence from GH pulse.
Weeks 1-2: Cumulative IGF-1 elevation becomes measurable above baseline in sustained dosing protocols. Nitrogen retention improves with positive protein balance in skeletal muscle. Sleep architecture shifts — increased slow-wave (stage 3) sleep correlates with nocturnal GH pulse augmentation. Early improvements in recovery from exercise-induced muscle damage are reported.
Weeks 2-8: Progressive lean body mass accrual alongside measurable reduction in fat mass, particularly visceral adipose tissue. Collagen synthesis upregulation may improve connective tissue quality and joint resilience. IGF-1 levels plateau at a new elevated mean. Lipid panel improvements and enhanced glucose disposal (compensatory to GH insulin resistance) may be evident on bloodwork. Long-term beyond 8-12 weeks carries theoretical risk of receptor desensitization and requires cycling.

Cómo aprovecharlo al máximo

Monitor IGF-1 levels every 4-6 weeks during a cycle; target IGF-1 within the upper quartile of age-adjusted normal range, not supraphysiological levels
Implement a cyclic dosing protocol (e.g., 5 days on, 2 days off, or 8 weeks on, 4 weeks off) to minimize GHS-R1a desensitization
Administer injections in a fasted state (1.5-2 hours post-meal minimum) to avoid blunting of GH pulse by insulin and somatostatin co-stimulation
Consider pairing with a GHRH analogue (e.g., Mod-GRF 1-29/CJC-1295 no-DAC) to synergistically amplify GH pulse amplitude through complementary receptor pathways

Efectos secundarios comunes

Transient hypercortisolemia and hyperprolactinemia at doses above 200 mcg — may impair sleep architecture and immune function with chronic elevation
Dose-dependent fluid retention secondary to IGF-1-mediated renal sodium retention — typically resolves within days of dose reduction
Mild post-injection insulin resistance window (30-90 min post-dose) due to GH-mediated counter-regulatory glucose effects — avoid carbohydrate intake around injection time

Mecanismo de acción

GHRP-3 is a synthetic hexapeptide that functions as a full agonist at the growth hormone secretagogue receptor 1a (GHS-R1a), a Gαq/11-coupled GPCR. Receptor activation leads to phospholipase C-beta stimulation, generating IP3 and DAG, which together mobilize intracellular calcium from the endoplasmic reticulum and activate PKC, culminating in exocytosis of GH-containing secretory granules from anterior pituitary somatotrophs. Simultaneously, GHRP-3 acts at hypothalamic GHS-R1a to suppress somatostatinergic tone (SST14/SST28), reducing inhibitory brake on GH secretion, and may potentiate GHRH neuron activity, creating a synergistic amplification of the GH pulse amplitude. GHRP-3's modified peptide backbone compared to GHRP-6 (substitution of specific aromatic residues) confers somewhat reduced affinity for ghrelin-associated appetite circuits in the arcuate nucleus and vagal afferents, explaining its comparatively attenuated orexigenic profile.

Following subcutaneous or intramuscular administration, GHRP-3 has a very short plasma half-life (~15-20 minutes) due to rapid proteolytic degradation. Despite this, it generates a GH pulse lasting approximately 90-180 minutes. Peak GH concentrations typically occur 15-30 minutes post-injection. Elevated GH stimulates hepatic IGF-1 synthesis over 4-8 hours. Chronic administration (weeks to months) leads to sustained elevation of mean 24-hour GH and IGF-1 levels, driving downstream anabolic, lipolytic, and tissue-repair pathways. Importantly, GHRP-3 preserves the pulsatile physiological pattern of GH secretion rather than producing the supraphysiological continuous elevation seen with exogenous recombinant GH.

Farmacodinamia

GH plasma concentration peaks 15-30 minutes post-injection with an injection-to-peak pharmacokinetic profile consistent across GHRP class compounds. IGF-1 elevation lags by approximately 6-12 hours and requires 1-3 weeks of repeated dosing to show statistically significant mean elevation above baseline in animal models. Cortisol and prolactin co-stimulation peaks concurrently with GH, typically returning to baseline within 60-90 minutes.

Sustained multi-week protocols in preclinical models demonstrate increased lean body mass, reduced adipose tissue (particularly visceral), enhanced collagen synthesis, improved nitrogen retention, accelerated wound healing, and favorable shifts in lipid profiles (reduced LDL, increased HDL). Endogenous IGF-1 elevation mediates most anabolic effects via PI3K/AKT/mTOR signaling in skeletal muscle and PI3K/AKT-mediated anti-apoptotic signaling in multiple tissue types. GH-mediated lipolysis occurs via HSL (hormone-sensitive lipase) activation and adipocyte beta-adrenergic sensitization.

Cronología

Days 1-3: GHS-R1a engagement produces measurable GH pulses within 30 minutes of each injection (confirmed in analogous peptide studies). Acute pharmacodynamic effects include transient hyperglycemia and cortisol elevation. Plasma half-life of ~15-20 minutes; no meaningful accumulation between doses. Users may notice mild injection site reactions and post-injection somnolence from GH pulse.
Weeks 1-2: Cumulative IGF-1 elevation becomes measurable above baseline in sustained dosing protocols. Nitrogen retention improves with positive protein balance in skeletal muscle. Sleep architecture shifts — increased slow-wave (stage 3) sleep correlates with nocturnal GH pulse augmentation. Early improvements in recovery from exercise-induced muscle damage are reported.
Weeks 2-8: Progressive lean body mass accrual alongside measurable reduction in fat mass, particularly visceral adipose tissue. Collagen synthesis upregulation may improve connective tissue quality and joint resilience. IGF-1 levels plateau at a new elevated mean. Lipid panel improvements and enhanced glucose disposal (compensatory to GH insulin resistance) may be evident on bloodwork. Long-term beyond 8-12 weeks carries theoretical risk of receptor desensitization and requires cycling.

Comparaciones

GHRP-3 — efectividad Moderate, seguridad Moderate, costo $$, Medium de usar
GHRP-2 — efectividad High, seguridad Moderate, costo $$, Medium de usar
Ipamorelin — efectividad Moderate, seguridad Good, costo $$, Medium de usar
Tesamorelin — efectividad High, seguridad Good, costo $$$$, Medium de usar

Efectos adversos

Comunes:

Transient hypercortisolemia and hyperprolactinemia at doses above 200 mcg — may impair sleep architecture and immune function with chronic elevation
Dose-dependent fluid retention secondary to IGF-1-mediated renal sodium retention — typically resolves within days of dose reduction
Mild post-injection insulin resistance window (30-90 min post-dose) due to GH-mediated counter-regulatory glucose effects — avoid carbohydrate intake around injection time

Raros:

Carpal tunnel syndrome-like symptoms (median nerve compression from fluid retention) — incidence estimated <5% at standard doses in analogous GHRP class compounds
Pituitary desensitization with chronic high-frequency dosing (>3x/day for extended periods) — theoretical based on receptor downregulation data from animal studies

Contraindicaciones y mitigación de riesgos

Contraindicado en:

Patients with IGF-1-sensitive malignancies (breast, prostate, colorectal cancer) — GH/IGF-1 axis upregulation may accelerate tumor proliferation via IGF-1R signaling
Individuals with active acromegaly, pituitary adenomas, or documented pituitary hyperfunction
Type 1 or poorly controlled Type 2 diabetics — GH-mediated insulin resistance may significantly worsen glycemic control
Patients on glucocorticoid therapy — may blunt GH pulse amplitude and confound cortisol monitoring

Monitor IGF-1 levels every 4-6 weeks during a cycle; target IGF-1 within the upper quartile of age-adjusted normal range, not supraphysiological levels
Implement a cyclic dosing protocol (e.g., 5 days on, 2 days off, or 8 weeks on, 4 weeks off) to minimize GHS-R1a desensitization
Administer injections in a fasted state (1.5-2 hours post-meal minimum) to avoid blunting of GH pulse by insulin and somatostatin co-stimulation
Consider pairing with a GHRH analogue (e.g., Mod-GRF 1-29/CJC-1295 no-DAC) to synergistically amplify GH pulse amplitude through complementary receptor pathways

Reference data

Specifications

Molecular formula: C₄₅H₅₅N₉O₆
Molecular weight: ~829.99 g/mol
Half-life: ~15-20 minutes (active pulse duration ~2-3 hours)
Route: Subcutaneous, Intramuscular
Cycle length: 8-12 weeks
Storage: Store lyophilized powder at -20°C for long-term stability (up to 24 months). After reconstitution with bacteriostatic water, refrigerate at 2-8°C and use within 28-30 days. Protect from light and repeated freeze-thaw cycles.
Legal status: Research chemical; not approved by FDA or EMA for human use. Legal to purchase for research purposes in most jurisdictions but prohibited in competitive sport by WADA.

FAQ

Common questions

How does GHRP-3 compare mechanistically to GHRP-2 and GHRP-6?

All three are GHS-R1a agonists, but differ in receptor binding affinity, selectivity, and off-target effects. GHRP-2 has the highest GHS-R1a affinity and produces the largest GH pulses but also the most pronounced cortisol and prolactin co-stimulation. GHRP-6 has significant ghrelin-like appetite-stimulating effects via arcuate nucleus GHS-R1a. GHRP-3's modified structure attempts to reduce orexigenic signaling while maintaining reasonable GH secretagogue potency — though head-to-head human comparison data are absent from peer-reviewed literature.

Does GHRP-3 suppress endogenous GHRH or somatostatin feedback?

GHRP-3 does not suppress endogenous GHRH. Rather, it reduces somatostatin inhibitory tone at the hypothalamic level and amplifies GHRH receptor signaling at the pituitary. This is mechanistically distinct from exogenous GH administration, which suppresses endogenous GH axis via negative feedback. Upon discontinuation of GHRP-3, endogenous pulsatile GH secretion patterns should normalize, though this has not been formally studied for GHRP-3 specifically.

What is the evidence basis for GHRP-3 specifically, versus the GHRP class generally?

GHRP-3 has significantly less published literature than GHRP-2 or GHRP-6. The mechanistic framework is extrapolated from the well-characterized GHRP class pharmacology (multiple peer-reviewed studies, including Bowers et al. seminal work from the 1990s-2000s) and ghrelin receptor biology. Species-specific GH responses, receptor density differences, and metabolic context all limit direct extrapolation from rodent studies to human outcomes. Clinical trials specifically for GHRP-3 are absent from the public literature as of 2024.

What is the evidence level?

This compound is classified as Animal data. Most data comes from preclinical animal studies. Human clinical trial evidence is limited or absent.

Research

Research & sources

Animal data

Current evidence for GHRP-3 is rated as Animal data. Research is based primarily on animal models.

1. Growth hormone-releasing peptides and their analogs (1998) — Frontiers in Neuroendocrinology, 19(1):47-72 — Bowers CY
2. Ghrelin: much more than a hunger hormone (2012) — Current Opinion in Clinical Nutrition & Metabolic Care, 15(5):428-434
3. The GH secretagogue receptor: its intracellular signaling and regulation (2007) — Trends in Endocrinology and Metabolism, 18(4):128-135
4. Growth hormone secretagogues: mechanism of action and use in cardiac cachexia (2003) — Endocrine, 22(1):65-70

Explore

Often discussed alongside

CJC-1295 · growth Ipamorelin · growth BPC-157 · healing TB-500 · healing IGF-1 LR3 · growth