Mechanism

How it works

Hexarelin binds to the growth hormone secretagogue receptor 1a (GHS-R1a) in the pituitary and hypothalamus, stimulating a robust release of endogenous growth hormone via activation of Gq/11 protein-coupled signaling and subsequent phospholipase C activation, leading to IP3-mediated calcium mobilization. It also activates CD36 scavenger receptors in cardiac tissue, producing GH-independent cardioprotective effects including reduced cardiomyocyte apoptosis and improved ventricular function. Additionally, hexarelin modulates cortistatin and somatostatin pathways to amplify net GH pulse amplitude.

Reported in research

Benefits

Potent stimulation of endogenous growth hormone release, among the strongest of any GH secretagogue peptide
Direct cardioprotective effects including improved cardiac output and reduced ischemia-reperfusion injury via CD36 receptor activation
Promotion of lean muscle mass accrual and reduction in adipose tissue through downstream IGF-1 elevation
Potential improvements in bone mineral density and connective tissue repair through GH/IGF-1 axis activation

Context, not a prescription

Dosing

Typical range: 100–200 mcg per injection, 1–2x daily (Subcutaneous, Intramuscular)
Cycle length: 4–8 weeks with a break equal to cycle length recommended to prevent desensitization
Half-life: ~30–60 minutes (active; peak GH response within ~20–30 minutes)

Safety

Side effects & contraindications

Possible side effects

Increased cortisol and prolactin levels with regular dosing
Elevated appetite and water retention due to GH and ghrelin-mimetic activity
Facial flushing and tingling sensations, particularly at higher doses
Transient fatigue or lethargy following injection
Pituitary desensitization with prolonged continuous use, reducing GH response over time
Possible numbness or tingling in extremities (carpal tunnel-like symptoms at high dose)

Contraindications

Active malignancy or cancer history — GH elevation may promote tumor growth
Acromegaly or known GH excess conditions
Pregnancy or breastfeeding
Diabetes mellitus or significant insulin resistance — IGF-1 elevation may worsen glycemic control
History of pituitary tumors or adenomas

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

In depth

Full profile

What it does

You may notice improved sleep quality in the first week, followed by gradual improvements in muscle fullness, strength, and reduced body fat over weeks 2–8. Some users also report better joint comfort and faster recovery from exercise.

How it works

Think of your pituitary gland as a gas station pump and growth hormone as the fuel. Hexarelin is like pressing the pump handle — it makes the station release a big burst of fuel into your body's engine on demand.

After injection, Hexarelin travels through your bloodstream to the pituitary gland and hypothalamus, where it triggers a powerful pulse of growth hormone. That GH then travels to the liver and muscles, promoting tissue repair, fat burning, and muscle building. Separately, it also acts on heart cells to help protect them from damage.

What to expect

Most users report a noticeable warm flush or tingling within 15–30 minutes of injection, which corresponds to the GH pulse. Noticeable body composition changes typically begin within 2–4 weeks of consistent use.

Week 1: Immediate GH pulses occur with each injection. You may notice improved sleep depth, mild water retention, and increased appetite. Some users feel a warm flush shortly after injecting.
Weeks 2–4: IGF-1 levels begin rising, supporting muscle protein synthesis and fat metabolism. Noticeable improvements in recovery time after workouts, and early signs of improved muscle fullness.
Weeks 4–8: More significant body composition changes become apparent — lean mass increases and body fat begins to decrease. Strength and exercise performance often improve. Pituitary desensitization may start to blunt GH response if dosing daily without breaks.

Good to know

Start at the lower end of the dose range (100 mcg) to assess your personal response before increasing
Cycle on and off (e.g., 6 weeks on, 6 weeks off) to prevent receptor desensitization and cortisol accumulation
Monitor fasting blood glucose periodically if you have any metabolic concerns
Inject on an empty stomach or at bedtime to maximize GH pulse magnitude

Staying safe

Increased hunger, especially soon after injection
Mild facial flushing or warm tingling sensation
Slight water retention, especially in the first few weeks
Mild tiredness after injection

Avoid if you have:

Anyone with a history of cancer or currently undergoing cancer treatment
People with type 2 diabetes or poorly controlled blood sugar
Pregnant or breastfeeding women
Anyone with known pituitary conditions

Overview

Documented physiological changes with regular administration include: elevated serum IGF-1 (typically 20–40% above baseline in clinical studies), increased lean body mass via positive nitrogen balance and enhanced protein synthesis through mTOR/S6K1 pathway activation, lipolytic activity in adipose tissue through GH-mediated HSL upregulation, improved slow-wave sleep architecture through GH's role in delta-wave sleep regulation, and measurable improvements in cardiac ejection fraction in animal cardiomyopathy models.

How it works

GHS-R1a functions as a master ignition switch for somatotroph firing. Hexarelin is a high-affinity key that turns the switch more forcefully than endogenous ghrelin, while simultaneously jamming the brake pedal (somatostatin suppression) to maximize net GH output — analogous to flooring the accelerator while disabling the governor on an engine.

Following subcutaneous administration, hexarelin is rapidly absorbed with a Tmax of approximately 15–30 minutes. It binds GHS-R1a with greater affinity than GHRP-6 but with somewhat lower selectivity, resulting in concurrent elevation of GH, cortisol, and prolactin. Peak serum GH typically reaches 40–80 ng/mL in healthy adults (dose-dependent), compared to 15–30 ng/mL for GHRP-6 and 5–15 ng/mL for ipamorelin at equivalent doses. The downstream IGF-1 rise is measurable within 24–72 hours of repeated dosing. At the cardiac level, hexarelin has demonstrated efficacy in rodent models of dilated cardiomyopathy and ischemia-reperfusion injury by attenuating mitochondrial cytochrome c release and reducing caspase-3 activation.

Onset & timeline

Pharmacokinetic studies demonstrate peak plasma hexarelin concentrations within 15 minutes post-injection with a half-life of approximately 30–60 minutes. Peak serum GH response occurs at 15–30 minutes post-dose. IGF-1 elevation, reflecting hepatic GH signaling, becomes statistically significant after 5–7 days of twice-daily dosing. Pituitary desensitization via GHS-R1a downregulation is detectable with continuous daily administration beyond 4 weeks, manifesting as a progressive reduction in peak GH response (up to 50% blunting reported in some studies).

Days 1–3: Immediate pharmacodynamic response: each injection produces a measurable GH pulse (peak at ~20 min, return to baseline by ~90 min). Cortisol and prolactin transiently elevated. Users may notice mild fluid retention and increased appetite via ghrelin-mimetic orexigenic activity. GHS-R1a occupancy and internalization begins with each dosing event.
Weeks 1–2: IGF-1 begins to rise measurably, reflecting cumulative hepatic GH signaling. Increased nitrogen retention supports enhanced muscle protein synthesis. Sleep quality improvements often emerge due to GH's role in slow-wave (stage 3) sleep enhancement. Early signs of lipolysis in visceral and subcutaneous adipose may be detected biochemically (elevated free fatty acids post-dose).
Weeks 2–8: Body composition changes become clinically apparent: lean mass accrual and measurable reduction in fat mass (particularly visceral). Strength and recovery metrics improve. Pituitary desensitization begins to manifest beyond week 4 with continuous daily use, evidenced by declining peak GH response. Cardiac-protective effects (if applicable) are primarily supported by animal data and require longer-duration dosing to assess in humans. Cortisol and prolactin elevation should be monitored to manage adverse hormonal effects.

Getting the most from it

Administer in a pulsatile pattern (1–2x daily) rather than continuous infusion to mimic physiological GH secretion and minimize receptor desensitization
Implement 5-days-on/2-days-off or 4-weeks-on/4-weeks-off cycling protocols based on evidence of GHS-R1a downregulation kinetics
Consider stacking with CJC-1295 or Mod GRF(1-29) rather than increasing hexarelin dose — GHRH/GHRP synergy produces supraadditive GH release at lower individual doses, reducing cortisol/prolactin burden
Monitor fasting insulin, glucose, and HbA1c quarterly; monitor IGF-1 to avoid supraphysiological elevation (target: upper quartile of age-adjusted normal range)
Administer injections at bedtime in a fasted state (minimum 2 hours post-meal) to capitalize on endogenous GH pulse timing and minimize insulin-mediated blunting

Common side effects

Hypercortisolemia: Cortisol elevation of 50–200% above baseline is documented in human trials, potentially increasing risk of insulin resistance, mood disturbance, and immune suppression with prolonged use
Hyperprolactinemia: Prolactin elevation (typically 20–50% above baseline) may cause mild gynecomastia or decreased libido in sensitive individuals
GH-mediated fluid retention due to renal tubular sodium reabsorption; typically transient and dose-dependent
Elevated fasting blood glucose via GH-induced insulin resistance; clinically significant at higher doses

Mechanism of action

Hexarelin (His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH₂) is a synthetic hexapeptide GHRP that acts as a full agonist at the GHS-R1a (ghrelin receptor), a Gq/11 protein-coupled receptor expressed in the arcuate nucleus, pituitary somatotrophs, and cardiac tissue. GHS-R1a activation triggers phospholipase C-β, generating IP3 and DAG, which mobilize intracellular calcium and activate PKC, leading to depolarization of somatotrophs and a sharp GH secretory burst. Hexarelin also suppresses hypothalamic somatostatin tone indirectly, amplifying GH pulse amplitude synergistically when combined with GHRH analogs. At the cardiac level, hexarelin activates the CD36 scavenger receptor — a non-GHS-R1a pathway — in cardiomyocytes, triggering ERK1/2 and PI3K/Akt survival signaling, reducing apoptosis, and improving calcium handling. This cardiac effect is observed even in GH-deficient animal models, confirming GH-independence.

Following subcutaneous administration, hexarelin is rapidly absorbed with a Tmax of approximately 15–30 minutes. It binds GHS-R1a with greater affinity than GHRP-6 but with somewhat lower selectivity, resulting in concurrent elevation of GH, cortisol, and prolactin. Peak serum GH typically reaches 40–80 ng/mL in healthy adults (dose-dependent), compared to 15–30 ng/mL for GHRP-6 and 5–15 ng/mL for ipamorelin at equivalent doses. The downstream IGF-1 rise is measurable within 24–72 hours of repeated dosing. At the cardiac level, hexarelin has demonstrated efficacy in rodent models of dilated cardiomyopathy and ischemia-reperfusion injury by attenuating mitochondrial cytochrome c release and reducing caspase-3 activation.

Pharmacodynamics

Pharmacokinetic studies demonstrate peak plasma hexarelin concentrations within 15 minutes post-injection with a half-life of approximately 30–60 minutes. Peak serum GH response occurs at 15–30 minutes post-dose. IGF-1 elevation, reflecting hepatic GH signaling, becomes statistically significant after 5–7 days of twice-daily dosing. Pituitary desensitization via GHS-R1a downregulation is detectable with continuous daily administration beyond 4 weeks, manifesting as a progressive reduction in peak GH response (up to 50% blunting reported in some studies).

Documented physiological changes with regular administration include: elevated serum IGF-1 (typically 20–40% above baseline in clinical studies), increased lean body mass via positive nitrogen balance and enhanced protein synthesis through mTOR/S6K1 pathway activation, lipolytic activity in adipose tissue through GH-mediated HSL upregulation, improved slow-wave sleep architecture through GH's role in delta-wave sleep regulation, and measurable improvements in cardiac ejection fraction in animal cardiomyopathy models.

Timeline

Days 1–3: Immediate pharmacodynamic response: each injection produces a measurable GH pulse (peak at ~20 min, return to baseline by ~90 min). Cortisol and prolactin transiently elevated. Users may notice mild fluid retention and increased appetite via ghrelin-mimetic orexigenic activity. GHS-R1a occupancy and internalization begins with each dosing event.
Weeks 1–2: IGF-1 begins to rise measurably, reflecting cumulative hepatic GH signaling. Increased nitrogen retention supports enhanced muscle protein synthesis. Sleep quality improvements often emerge due to GH's role in slow-wave (stage 3) sleep enhancement. Early signs of lipolysis in visceral and subcutaneous adipose may be detected biochemically (elevated free fatty acids post-dose).
Weeks 2–8: Body composition changes become clinically apparent: lean mass accrual and measurable reduction in fat mass (particularly visceral). Strength and recovery metrics improve. Pituitary desensitization begins to manifest beyond week 4 with continuous daily use, evidenced by declining peak GH response. Cardiac-protective effects (if applicable) are primarily supported by animal data and require longer-duration dosing to assess in humans. Cortisol and prolactin elevation should be monitored to manage adverse hormonal effects.

Comparisons

Hexarelin Acetate — effectiveness Very High, safety Moderate, cost $$, Medium to use
Ipamorelin — effectiveness High, safety Good, cost $$, Medium to use
CJC-1295 + Ipamorelin Blend — effectiveness Very High, safety Good, cost $$$, Low to use
Sermorelin — effectiveness Moderate, safety Good, cost $$, Low to use

Adverse effects

Common:

Hypercortisolemia: Cortisol elevation of 50–200% above baseline is documented in human trials, potentially increasing risk of insulin resistance, mood disturbance, and immune suppression with prolonged use
Hyperprolactinemia: Prolactin elevation (typically 20–50% above baseline) may cause mild gynecomastia or decreased libido in sensitive individuals
GH-mediated fluid retention due to renal tubular sodium reabsorption; typically transient and dose-dependent
Elevated fasting blood glucose via GH-induced insulin resistance; clinically significant at higher doses

Rare:

Carpal tunnel syndrome at doses exceeding 200 mcg/day due to GH-driven fluid accumulation in the carpal tunnel; incidence estimated <5% in clinical range dosing
Transient orthostatic hypotension immediately post-injection reported in isolated cases
Pituitary desensitization syndrome with continuous high-dose use — requires extended washout to restore baseline GHS-R1a sensitivity

Contraindications & risk mitigation

Contraindicated in:

Active neoplasia or personal/family history of hormone-sensitive cancers — IGF-1 elevation can act as a mitogenic signal via IGF-1R/PI3K/mTOR pathways
Patients with HPA axis dysregulation, Cushing's syndrome, or adrenal insufficiency
Type 1 or Type 2 diabetes with suboptimal glycemic control — GH-induced insulin resistance may significantly impair glucose homeostasis
Patients on glucocorticoids or other HPA-active medications — additive cortisol effects
Individuals with acromegaly or known GH hypersecretion disorders

Administer in a pulsatile pattern (1–2x daily) rather than continuous infusion to mimic physiological GH secretion and minimize receptor desensitization
Implement 5-days-on/2-days-off or 4-weeks-on/4-weeks-off cycling protocols based on evidence of GHS-R1a downregulation kinetics
Consider stacking with CJC-1295 or Mod GRF(1-29) rather than increasing hexarelin dose — GHRH/GHRP synergy produces supraadditive GH release at lower individual doses, reducing cortisol/prolactin burden
Monitor fasting insulin, glucose, and HbA1c quarterly; monitor IGF-1 to avoid supraphysiological elevation (target: upper quartile of age-adjusted normal range)
Administer injections at bedtime in a fasted state (minimum 2 hours post-meal) to capitalize on endogenous GH pulse timing and minimize insulin-mediated blunting

Qué hace

You may notice improved sleep quality in the first week, followed by gradual improvements in muscle fullness, strength, and reduced body fat over weeks 2–8. Some users also report better joint comfort and faster recovery from exercise.

Cómo funciona

Think of your pituitary gland as a gas station pump and growth hormone as the fuel. Hexarelin is like pressing the pump handle — it makes the station release a big burst of fuel into your body's engine on demand.

After injection, Hexarelin travels through your bloodstream to the pituitary gland and hypothalamus, where it triggers a powerful pulse of growth hormone. That GH then travels to the liver and muscles, promoting tissue repair, fat burning, and muscle building. Separately, it also acts on heart cells to help protect them from damage.

Qué esperar

Most users report a noticeable warm flush or tingling within 15–30 minutes of injection, which corresponds to the GH pulse. Noticeable body composition changes typically begin within 2–4 weeks of consistent use.

Week 1: Immediate GH pulses occur with each injection. You may notice improved sleep depth, mild water retention, and increased appetite. Some users feel a warm flush shortly after injecting.
Weeks 2–4: IGF-1 levels begin rising, supporting muscle protein synthesis and fat metabolism. Noticeable improvements in recovery time after workouts, and early signs of improved muscle fullness.
Weeks 4–8: More significant body composition changes become apparent — lean mass increases and body fat begins to decrease. Strength and exercise performance often improve. Pituitary desensitization may start to blunt GH response if dosing daily without breaks.

Bueno saber

Start at the lower end of the dose range (100 mcg) to assess your personal response before increasing
Cycle on and off (e.g., 6 weeks on, 6 weeks off) to prevent receptor desensitization and cortisol accumulation
Monitor fasting blood glucose periodically if you have any metabolic concerns
Inject on an empty stomach or at bedtime to maximize GH pulse magnitude

Manteniéndose seguro

Increased hunger, especially soon after injection
Mild facial flushing or warm tingling sensation
Slight water retention, especially in the first few weeks
Mild tiredness after injection

Evitar si tienes:

Anyone with a history of cancer or currently undergoing cancer treatment
People with type 2 diabetes or poorly controlled blood sugar
Pregnant or breastfeeding women
Anyone with known pituitary conditions

Descripción general

Documented physiological changes with regular administration include: elevated serum IGF-1 (typically 20–40% above baseline in clinical studies), increased lean body mass via positive nitrogen balance and enhanced protein synthesis through mTOR/S6K1 pathway activation, lipolytic activity in adipose tissue through GH-mediated HSL upregulation, improved slow-wave sleep architecture through GH's role in delta-wave sleep regulation, and measurable improvements in cardiac ejection fraction in animal cardiomyopathy models.

Cómo funciona

GHS-R1a functions as a master ignition switch for somatotroph firing. Hexarelin is a high-affinity key that turns the switch more forcefully than endogenous ghrelin, while simultaneously jamming the brake pedal (somatostatin suppression) to maximize net GH output — analogous to flooring the accelerator while disabling the governor on an engine.

Following subcutaneous administration, hexarelin is rapidly absorbed with a Tmax of approximately 15–30 minutes. It binds GHS-R1a with greater affinity than GHRP-6 but with somewhat lower selectivity, resulting in concurrent elevation of GH, cortisol, and prolactin. Peak serum GH typically reaches 40–80 ng/mL in healthy adults (dose-dependent), compared to 15–30 ng/mL for GHRP-6 and 5–15 ng/mL for ipamorelin at equivalent doses. The downstream IGF-1 rise is measurable within 24–72 hours of repeated dosing. At the cardiac level, hexarelin has demonstrated efficacy in rodent models of dilated cardiomyopathy and ischemia-reperfusion injury by attenuating mitochondrial cytochrome c release and reducing caspase-3 activation.

Inicio y cronología

Pharmacokinetic studies demonstrate peak plasma hexarelin concentrations within 15 minutes post-injection with a half-life of approximately 30–60 minutes. Peak serum GH response occurs at 15–30 minutes post-dose. IGF-1 elevation, reflecting hepatic GH signaling, becomes statistically significant after 5–7 days of twice-daily dosing. Pituitary desensitization via GHS-R1a downregulation is detectable with continuous daily administration beyond 4 weeks, manifesting as a progressive reduction in peak GH response (up to 50% blunting reported in some studies).

Days 1–3: Immediate pharmacodynamic response: each injection produces a measurable GH pulse (peak at ~20 min, return to baseline by ~90 min). Cortisol and prolactin transiently elevated. Users may notice mild fluid retention and increased appetite via ghrelin-mimetic orexigenic activity. GHS-R1a occupancy and internalization begins with each dosing event.
Weeks 1–2: IGF-1 begins to rise measurably, reflecting cumulative hepatic GH signaling. Increased nitrogen retention supports enhanced muscle protein synthesis. Sleep quality improvements often emerge due to GH's role in slow-wave (stage 3) sleep enhancement. Early signs of lipolysis in visceral and subcutaneous adipose may be detected biochemically (elevated free fatty acids post-dose).
Weeks 2–8: Body composition changes become clinically apparent: lean mass accrual and measurable reduction in fat mass (particularly visceral). Strength and recovery metrics improve. Pituitary desensitization begins to manifest beyond week 4 with continuous daily use, evidenced by declining peak GH response. Cardiac-protective effects (if applicable) are primarily supported by animal data and require longer-duration dosing to assess in humans. Cortisol and prolactin elevation should be monitored to manage adverse hormonal effects.

Cómo aprovecharlo al máximo

Administer in a pulsatile pattern (1–2x daily) rather than continuous infusion to mimic physiological GH secretion and minimize receptor desensitization
Implement 5-days-on/2-days-off or 4-weeks-on/4-weeks-off cycling protocols based on evidence of GHS-R1a downregulation kinetics
Consider stacking with CJC-1295 or Mod GRF(1-29) rather than increasing hexarelin dose — GHRH/GHRP synergy produces supraadditive GH release at lower individual doses, reducing cortisol/prolactin burden
Monitor fasting insulin, glucose, and HbA1c quarterly; monitor IGF-1 to avoid supraphysiological elevation (target: upper quartile of age-adjusted normal range)
Administer injections at bedtime in a fasted state (minimum 2 hours post-meal) to capitalize on endogenous GH pulse timing and minimize insulin-mediated blunting

Efectos secundarios comunes

Hypercortisolemia: Cortisol elevation of 50–200% above baseline is documented in human trials, potentially increasing risk of insulin resistance, mood disturbance, and immune suppression with prolonged use
Hyperprolactinemia: Prolactin elevation (typically 20–50% above baseline) may cause mild gynecomastia or decreased libido in sensitive individuals
GH-mediated fluid retention due to renal tubular sodium reabsorption; typically transient and dose-dependent
Elevated fasting blood glucose via GH-induced insulin resistance; clinically significant at higher doses

Mecanismo de acción

Hexarelin (His-D-2-Me-Trp-Ala-Trp-D-Phe-Lys-NH₂) is a synthetic hexapeptide GHRP that acts as a full agonist at the GHS-R1a (ghrelin receptor), a Gq/11 protein-coupled receptor expressed in the arcuate nucleus, pituitary somatotrophs, and cardiac tissue. GHS-R1a activation triggers phospholipase C-β, generating IP3 and DAG, which mobilize intracellular calcium and activate PKC, leading to depolarization of somatotrophs and a sharp GH secretory burst. Hexarelin also suppresses hypothalamic somatostatin tone indirectly, amplifying GH pulse amplitude synergistically when combined with GHRH analogs. At the cardiac level, hexarelin activates the CD36 scavenger receptor — a non-GHS-R1a pathway — in cardiomyocytes, triggering ERK1/2 and PI3K/Akt survival signaling, reducing apoptosis, and improving calcium handling. This cardiac effect is observed even in GH-deficient animal models, confirming GH-independence.

Following subcutaneous administration, hexarelin is rapidly absorbed with a Tmax of approximately 15–30 minutes. It binds GHS-R1a with greater affinity than GHRP-6 but with somewhat lower selectivity, resulting in concurrent elevation of GH, cortisol, and prolactin. Peak serum GH typically reaches 40–80 ng/mL in healthy adults (dose-dependent), compared to 15–30 ng/mL for GHRP-6 and 5–15 ng/mL for ipamorelin at equivalent doses. The downstream IGF-1 rise is measurable within 24–72 hours of repeated dosing. At the cardiac level, hexarelin has demonstrated efficacy in rodent models of dilated cardiomyopathy and ischemia-reperfusion injury by attenuating mitochondrial cytochrome c release and reducing caspase-3 activation.

Farmacodinamia

Pharmacokinetic studies demonstrate peak plasma hexarelin concentrations within 15 minutes post-injection with a half-life of approximately 30–60 minutes. Peak serum GH response occurs at 15–30 minutes post-dose. IGF-1 elevation, reflecting hepatic GH signaling, becomes statistically significant after 5–7 days of twice-daily dosing. Pituitary desensitization via GHS-R1a downregulation is detectable with continuous daily administration beyond 4 weeks, manifesting as a progressive reduction in peak GH response (up to 50% blunting reported in some studies).

Documented physiological changes with regular administration include: elevated serum IGF-1 (typically 20–40% above baseline in clinical studies), increased lean body mass via positive nitrogen balance and enhanced protein synthesis through mTOR/S6K1 pathway activation, lipolytic activity in adipose tissue through GH-mediated HSL upregulation, improved slow-wave sleep architecture through GH's role in delta-wave sleep regulation, and measurable improvements in cardiac ejection fraction in animal cardiomyopathy models.

Cronología

Days 1–3: Immediate pharmacodynamic response: each injection produces a measurable GH pulse (peak at ~20 min, return to baseline by ~90 min). Cortisol and prolactin transiently elevated. Users may notice mild fluid retention and increased appetite via ghrelin-mimetic orexigenic activity. GHS-R1a occupancy and internalization begins with each dosing event.
Weeks 1–2: IGF-1 begins to rise measurably, reflecting cumulative hepatic GH signaling. Increased nitrogen retention supports enhanced muscle protein synthesis. Sleep quality improvements often emerge due to GH's role in slow-wave (stage 3) sleep enhancement. Early signs of lipolysis in visceral and subcutaneous adipose may be detected biochemically (elevated free fatty acids post-dose).
Weeks 2–8: Body composition changes become clinically apparent: lean mass accrual and measurable reduction in fat mass (particularly visceral). Strength and recovery metrics improve. Pituitary desensitization begins to manifest beyond week 4 with continuous daily use, evidenced by declining peak GH response. Cardiac-protective effects (if applicable) are primarily supported by animal data and require longer-duration dosing to assess in humans. Cortisol and prolactin elevation should be monitored to manage adverse hormonal effects.

Comparaciones

Hexarelin Acetate — efectividad Very High, seguridad Moderate, costo $$, Medium de usar
Ipamorelin — efectividad High, seguridad Good, costo $$, Medium de usar
CJC-1295 + Ipamorelin Blend — efectividad Very High, seguridad Good, costo $$$, Low de usar
Sermorelin — efectividad Moderate, seguridad Good, costo $$, Low de usar

Efectos adversos

Comunes:

Hypercortisolemia: Cortisol elevation of 50–200% above baseline is documented in human trials, potentially increasing risk of insulin resistance, mood disturbance, and immune suppression with prolonged use
Hyperprolactinemia: Prolactin elevation (typically 20–50% above baseline) may cause mild gynecomastia or decreased libido in sensitive individuals
GH-mediated fluid retention due to renal tubular sodium reabsorption; typically transient and dose-dependent
Elevated fasting blood glucose via GH-induced insulin resistance; clinically significant at higher doses

Raros:

Carpal tunnel syndrome at doses exceeding 200 mcg/day due to GH-driven fluid accumulation in the carpal tunnel; incidence estimated <5% in clinical range dosing
Transient orthostatic hypotension immediately post-injection reported in isolated cases
Pituitary desensitization syndrome with continuous high-dose use — requires extended washout to restore baseline GHS-R1a sensitivity

Contraindicaciones y mitigación de riesgos

Contraindicado en:

Active neoplasia or personal/family history of hormone-sensitive cancers — IGF-1 elevation can act as a mitogenic signal via IGF-1R/PI3K/mTOR pathways
Patients with HPA axis dysregulation, Cushing's syndrome, or adrenal insufficiency
Type 1 or Type 2 diabetes with suboptimal glycemic control — GH-induced insulin resistance may significantly impair glucose homeostasis
Patients on glucocorticoids or other HPA-active medications — additive cortisol effects
Individuals with acromegaly or known GH hypersecretion disorders

Administer in a pulsatile pattern (1–2x daily) rather than continuous infusion to mimic physiological GH secretion and minimize receptor desensitization
Implement 5-days-on/2-days-off or 4-weeks-on/4-weeks-off cycling protocols based on evidence of GHS-R1a downregulation kinetics
Consider stacking with CJC-1295 or Mod GRF(1-29) rather than increasing hexarelin dose — GHRH/GHRP synergy produces supraadditive GH release at lower individual doses, reducing cortisol/prolactin burden
Monitor fasting insulin, glucose, and HbA1c quarterly; monitor IGF-1 to avoid supraphysiological elevation (target: upper quartile of age-adjusted normal range)
Administer injections at bedtime in a fasted state (minimum 2 hours post-meal) to capitalize on endogenous GH pulse timing and minimize insulin-mediated blunting

Reference data

Specifications

Molecular formula: C₄₇H₅₈N₁₂O₆
Molecular weight: 887.05 g/mol (free base); ~959.1 g/mol as acetate salt
Half-life: ~30–60 minutes (active; peak GH response within ~20–30 minutes)
Route: Subcutaneous, Intramuscular
Cycle length: 4–8 weeks with a break equal to cycle length recommended to prevent desensitization
Storage: Store lyophilized powder at 2–8°C (refrigerated) or -20°C for long-term storage. After reconstitution with bacteriostatic water, store at 2–8°C and use within 28 days. Protect from light and repeated freeze-thaw cycles.
Legal status: Research chemical; not approved by FDA or EMA for human therapeutic use. Banned by WADA in competitive sports. Legal to purchase for research purposes in most jurisdictions; status varies by country.

FAQ

Common questions

What is the pharmacological basis for hexarelin's cardiac effects independent of GH?

Hexarelin activates the CD36 (fatty acid translocase) scavenger receptor in cardiomyocytes through a GHS-R1a-independent mechanism. This activates downstream PI3K/Akt and ERK1/2 survival pathways, reduces cytochrome c release from mitochondria, and suppresses caspase-3 activation — collectively reducing apoptosis following ischemic insult. This was demonstrated in hypophysectomized rat models where hexarelin improved ventricular function despite absent pituitary-derived GH (Torsello et al., Endocrine 2001; Broglio et al., JCEM 1999).

How does hexarelin compare to GHRP-6 and ipamorelin at the receptor level?

All three are GHS-R1a agonists. Hexarelin demonstrates the highest GHS-R1a binding affinity of the three, producing the largest GH pulses but also the greatest off-target cortisol and prolactin elevation due to less receptor subtype selectivity. GHRP-6 has intermediate potency with significant appetite stimulation via hypothalamic neuropeptide Y. Ipamorelin is the most selective GHS-R1a agonist with minimal cortisol and prolactin elevation, making it preferable for long-term use despite a smaller GH pulse. Hexarelin is uniquely the only GHRP with documented CD36-mediated cardiac activity.

Does hexarelin suppress endogenous GHRH or somatostatin feedback?

Hexarelin primarily acts at the pituitary somatotroph level as a direct secretagogue and also suppresses hypothalamic somatostatin tone, which amplifies net GH output. It does not suppress endogenous GHRH secretion from the arcuate nucleus. In fact, hexarelin and GHRH analogs act synergistically — their co-administration produces GH responses exceeding the arithmetic sum of each alone, a phenomenon well-documented in clinical dose-response studies (Ghigo et al., JCEM 1994).

What is the evidence level?

This compound is classified as Limited human data. Some human data exists but trials are small, short-term, or not yet replicated.

Research

Research & sources

Limited human

Current evidence for Hexarelin Acetate is rated as Limited human data. Limited human data is available.

1. Growth hormone-releasing activity of hexarelin, a new synthetic hexapeptide, after intravenous, subcutaneous, intranasal, and oral administration in man (1994) — Journal of Clinical Endocrinology & Metabolism, Ghigo E, et al. 79(3):666-669
2. Hexarelin, a synthetic growth hormone-releasing peptide, acts on the hypothalamus as well as the pituitary in normal subjects (1996) — Journal of Clinical Endocrinology & Metabolism, Arvat E, et al.
3. Cardiovascular actions of growth hormone secretagogues (1999) — Journal of Clinical Endocrinology & Metabolism, Broglio F, et al.
4. Hexarelin, a growth hormone-releasing peptide, protects cardiomyocytes from apoptosis (2001) — Endocrine, Torsello A, et al.
5. The GH secretagogue hexarelin stimulates the hypothalamo-pituitary-adrenal axis via arginine vasopressin (1998) — Endocrinology, Maccario M, et al.

Explore

Often discussed alongside

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