Growth Hormone Peptides: CJC-1295, Ipamorelin, Sermorelin, Tesamorelin, MK-677, GHRP-2, GHRP-6

Overview

Growth hormone (GH) secretagogues are a class of compounds that stimulate the pituitary gland to release more of the body's own growth hormone. Unlike exogenous GH (recombinant human growth hormone, or rhGH), which directly replaces GH, secretagogues work by amplifying the body's natural GH production and release cycles. This distinction is important because it means GH secretagogues generally produce more physiological GH pulsing patterns rather than the supraphysiological levels seen with rhGH injection.

These compounds fall into three main categories based on their mechanism of action:

• GHRH analogs (CJC-1295, Sermorelin, Tesamorelin) — synthetic versions of growth hormone-releasing hormone, the hypothalamic signal that tells the pituitary to release GH
• Ghrelin mimetics / GHRPs (GHRP-2, GHRP-6, Ipamorelin) — compounds that mimic ghrelin, the "hunger hormone" that also stimulates GH release through the GHS-R1a receptor
• Non-peptide GH secretagogues (MK-677/Ibutamoren) — orally active small molecules that act on the ghrelin receptor but are not peptides

Of all the peptides discussed on this page, only Tesamorelin (brand name Egrifta) is currently FDA-approved, and only for a single indication: reduction of excess abdominal fat in HIV-infected patients with lipodystrophy (Dhillon, 2011). Sermorelin (brand name Geref) was previously FDA-approved for diagnostic use and GH-deficiency treatment in children but was voluntarily discontinued by its manufacturer for commercial reasons — not safety concerns (Frohman & Jansson, 1986). All other peptides on this page are used off-label, through compounding pharmacies, or as research chemicals.

The primary effects sought from GH secretagogues include increased lean muscle mass, reduced body fat, improved recovery from exercise and injury, better sleep quality, and anti-aging effects on skin and connective tissue. These effects are mediated through increased GH and subsequently increased insulin-like growth factor 1 (IGF-1), which is produced by the liver in response to GH stimulation.

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

At a Glance

A quick-reference overview of peptides in this category — key facts, evidence level, and estimated cost.

Head-to-Head Comparison

Sources: Teichman et al. (2006) — CJC-1295; Raun et al. (1998) — Ipamorelin; Dhillon (2011) — Tesamorelin; Murphy et al. (1998) — MK-677; Bowers (1998) — GHRPs.

Mechanism Classes Explained

IGF-1 Effects Comparison

All GH secretagogues increase IGF-1 levels as a downstream effect of increased GH release. The magnitude and duration of IGF-1 elevation varies:

• CJC-1295 with DAC: Sustained IGF-1 elevation (60–100% increase over baseline sustained for days). In clinical studies, a single dose elevated IGF-1 for 9–11 days (Teichman et al., 2006)
• CJC-1295 (no DAC) + Ipamorelin: Pulsatile IGF-1 elevation; moderate sustained increase with regular dosing
• Sermorelin: Modest IGF-1 increase; more physiological pulsing pattern
• Tesamorelin: Clinically significant IGF-1 increase (documented in FDA trials for lipodystrophy) (Dhillon, 2011)
• MK-677: Sustained IGF-1 elevation (~40–60% increase) with daily oral dosing maintained over months (Murphy et al., 1998)
• GHRP-2/GHRP-6: Acute GH/IGF-1 spikes with each injection; less sustained than CJC-1295 with DAC

This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider.

GHRH Analogs: CJC-1295 and Sermorelin

CJC-1295

What It Is

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH) consisting of 29 amino acids (the bioactive fragment of the 44-amino-acid native GHRH) with modifications to extend its half-life. It exists in two forms:

• CJC-1295 with DAC (Drug Affinity Complex): Includes a maleimidopropionic acid moiety that binds covalently to serum albumin after injection, extending the half-life to approximately 8 days. This produces sustained GH elevation rather than pulsatile release (Teichman et al., 2006)
• CJC-1295 without DAC (also called Modified GRF 1-29 or Mod GRF): Shorter half-life (~30 minutes). Produces more physiological GH pulsing. Often combined with a GHRP (typically Ipamorelin) for synergistic effect

Evidence

In a clinical study of healthy adults aged 21–61, a single subcutaneous dose of CJC-1295 with DAC produced dose-dependent increases in GH (2–10 fold) and IGF-1 (1.5–3 fold), sustained for 6–8 days after injection. Mean IGF-1 levels remained elevated for up to 28 days after multiple doses (Teichman et al., 2006).

No large-scale Phase 3 clinical trials have been completed. The evidence base consists of Phase 1/2 pharmacokinetic and pharmacodynamic studies, plus extensive off-label clinical use documented in the anti-aging and sports medicine literature.

Side Effects

• Flushing and warmth at injection
• Headache
• Dizziness
• Injection site reactions (redness, swelling)
• Water retention
• With DAC: potential for sustained non-physiological GH elevation, which may increase insulin resistance over time

Dosing

Dosing should be determined by a qualified healthcare provider. CJC-1295 is not FDA-approved, and there is no standardized dosing protocol established through the regulatory approval process.

Legal Status & Cost

• FDA: Not approved. Available through compounding pharmacies.
• WADA: Prohibited (S2 category).
• Cost: Approximately $100–300/month through compounding pharmacies.

Sermorelin

What It Is

Sermorelin acetate is a synthetic peptide consisting of the first 29 amino acids of the 44-amino-acid human GHRH. It is the shortest fragment of GHRH that retains full biological activity at the GHRH receptor. Sermorelin was FDA-approved in 1997 under the brand name Geref Diagnostic for evaluating pituitary GH secretion capacity, and was also used for treatment of GH deficiency in children. The manufacturer (EMD Serono) voluntarily discontinued it in 2008 for commercial reasons, not safety concerns (Frohman & Jansson, 1986).

Evidence

• GH deficiency in children: Demonstrated efficacy in stimulating linear growth in GH-deficient children, leading to FDA approval (Frohman & Jansson, 1986)
• Adult GH stimulation: Extensive clinical data demonstrating reliable GH release in adults when administered subcutaneously (Walker, 2006)
• Anti-aging use: Used off-label for age-related GH decline. Several small clinical studies have documented improvements in body composition, sleep quality, and skin elasticity, but no large Phase 3 trials specifically for anti-aging indications

Side Effects

• Injection site reactions (pain, redness, swelling) — most common
• Facial flushing
• Headache
• Dizziness
• Transient tightness in chest (rare)
• Generally considered to have a favorable safety profile based on its period of FDA-approved use

Dosing

Dosing should be determined by a qualified healthcare provider. While sermorelin had established dosing when FDA-approved, its current use is off-label through compounding pharmacies.

Legal Status & Cost

• FDA: Previously approved (Geref); voluntarily discontinued. Still legally compounded by 503A/503B pharmacies.
• WADA: Prohibited (S2 category).
• Cost: Approximately $150–400/month through compounding pharmacies.

Ghrelin Mimetics: Ipamorelin, GHRP-2, and GHRP-6

Ipamorelin

What It Is

Ipamorelin is a synthetic pentapeptide and the first GH secretagogue described as "selective" — meaning it stimulates GH release with minimal effect on cortisol, prolactin, and other hormones. This selectivity distinguishes it from earlier GHRPs (GHRP-2, GHRP-6, hexarelin) that stimulate GH but also significantly raise cortisol and prolactin (Raun et al., 1998).

Evidence

• Selectivity: The landmark 1998 study by Raun et al. demonstrated that Ipamorelin releases GH with a potency comparable to GHRP-6 but without the dose-dependent increase in cortisol and prolactin seen with other GHRPs. Even at doses up to 200-fold above the ED50, it did not significantly release ACTH, cortisol, prolactin, or aldosterone (Raun et al., 1998)
• Clinical studies: Limited Phase 1/2 data in humans. Most clinical use is off-label through anti-aging and sports medicine clinics
• Combination therapy: Frequently combined with CJC-1295 (without DAC) to leverage the synergistic effect of simultaneous GHRH receptor and GHS receptor activation

Side Effects

• Headache
• Transient hunger immediately after injection
• Injection site reactions
• Water retention (mild)
• Generally considered to have the mildest side effect profile among GHRPs due to its selectivity

Dosing

Dosing should be determined by a qualified healthcare provider. Ipamorelin is not FDA-approved, and standardized human dosing has not been established through the regulatory process.

Legal Status & Cost

• FDA: Not approved. Available through compounding pharmacies.
• WADA: Prohibited (S2 category).
• Cost: Approximately $100–250/month through compounding pharmacies.

GHRP-2 (Growth Hormone Releasing Peptide-2)

What It Is

GHRP-2 (pralmorelin) is a synthetic hexapeptide that acts as a potent GH secretagogue through the GHS-R1a receptor. It is one of the most studied GHRPs and is used clinically in some countries (notably Japan, where it is approved as a diagnostic agent for GH deficiency under the name GHRP Kaken) (Bowers, 1998).

Evidence

• GH release: GHRP-2 produces robust GH release, typically greater than GHRP-6 on a per-dose basis. Extensively studied as a diagnostic tool for GH deficiency (Aimaretti et al., 1998)
• Hormonal effects: Unlike Ipamorelin, GHRP-2 stimulates modest increases in ACTH, cortisol, and prolactin in addition to GH (Bowers, 1998)
• Appetite: Increases appetite, though less intensely than GHRP-6

Side Effects

• Increased appetite
• Cortisol elevation (modest, dose-dependent)
• Prolactin elevation (modest)
• Water retention
• Injection site reactions
• Tingling/numbness (paresthesia)

Dosing

Dosing should be determined by a qualified healthcare provider.

Legal Status & Cost

• FDA: Not approved in the US. Approved as a diagnostic in Japan.
• WADA: Prohibited.
• Cost: Approximately $80–200/month through compounding pharmacies or research suppliers.

GHRP-6 (Growth Hormone Releasing Peptide-6)

What It Is

GHRP-6 is one of the earliest synthetic GH secretagogues, a hexapeptide that produces potent GH release through the GHS-R1a receptor. It was instrumental in the discovery and characterization of the ghrelin receptor. GHRP-6 is notable for producing the strongest appetite stimulation among the GHRPs, making it useful in clinical contexts where appetite enhancement is desired but problematic when appetite increase is unwanted (Bowers, 1998).

Evidence

• GH release: Potent and reliable GH release. Extensively used in research to characterize the GH secretagogue pathway (Bowers, 1998)
• Appetite stimulation: Produces intense, acute hunger — mediated through the same ghrelin receptor pathway that controls appetite signaling
• Hormonal effects: Raises cortisol, prolactin, and ACTH more significantly than Ipamorelin or GHRP-2 (Bowers, 1998)
• Cardioprotective effects: Some preclinical evidence suggests GHRP-6 may have cardioprotective properties independent of GH release

Side Effects

• Intense appetite increase (most pronounced of all GHRPs)
• Cortisol elevation
• Prolactin elevation
• Water retention / bloating
• Injection site reactions
• Dizziness

Dosing

Dosing should be determined by a qualified healthcare provider.

Legal Status & Cost

• FDA: Not approved.
• WADA: Prohibited.
• Cost: Approximately $60–150/month — generally the least expensive GHRP option.

MK-677 (Ibutamoren)

What It Is

MK-677, also known as Ibutamoren or Ibutamoren mesylate, is an orally active, non-peptide growth hormone secretagogue that mimics the action of ghrelin at the GHS-R1a receptor. Unlike the injectable GHRPs, MK-677 is a small molecule that can be taken as a capsule or tablet. It was developed by Merck and has been studied in clinical trials for growth hormone deficiency, muscle wasting, osteoporosis, and age-related frailty, but has never received FDA approval (Murphy et al., 1998).

Mechanism of Action

MK-677 binds to GHS-R1a receptors in the pituitary and hypothalamus, mimicking ghrelin's effect to stimulate GH release. Key pharmacological features:

• Oral bioavailability: Can be taken by mouth, unlike injectable GHRPs
• Long half-life: Approximately 24 hours, allowing once-daily dosing
• Sustained IGF-1 elevation: Daily administration produces persistent IGF-1 increases of approximately 40–60% above baseline (Murphy et al., 1998)
• Does not suppress natural GH: Unlike exogenous GH, MK-677 does not suppress the hypothalamic-pituitary GH axis

Evidence

• Diet-induced catabolism: In healthy volunteers on caloric restriction, MK-677 (25 mg/day) reversed diet-induced nitrogen loss and increased GH and IGF-1 levels, suggesting it could counteract muscle wasting during caloric deficit (Murphy et al., 1998)
• GH-deficient children: Oral ibutamoren increased GH and IGF-1 levels in GH-deficient children in a dose-dependent manner (Codner et al., 2001)
• Elderly subjects: A 2-year study in healthy elderly adults showed sustained IGF-1 elevation but did not demonstrate significant improvements in functional endpoints (Nass et al., 2008)
• Sleep quality: Clinical data suggests MK-677 increases REM sleep duration and sleep quality (Copinschi et al., 1997)
• Bone mineral density: Some evidence of improved bone mineral density markers in elderly populations, but no fracture endpoint data

Side Effects

MK-677 has a well-documented side effect profile from clinical trials:

• Increased appetite: Consistent and significant; related to ghrelin receptor activation
• Water retention / edema: Common, particularly in the first weeks of use. Can cause peripheral edema and joint stiffness
• Blood glucose elevation: MK-677 can increase fasting blood glucose and decrease insulin sensitivity. This is clinically significant — the 2-year elderly study noted increased fasting glucose and HbA1c levels (Nass et al., 2008)
• Fatigue and lethargy: Particularly when taken in the morning; many users take it at bedtime
• Joint pain / muscle pain: Related to GH-mediated water retention and tissue effects
• Numbness/tingling (paresthesia): Occasional

Dosing

Dosing should be determined by a qualified healthcare provider. MK-677 is not FDA-approved, and there is no standardized clinical dosing protocol. Clinical trials have used various doses, and the appropriate dose for any individual depends on clinical context.

Legal Status

• United States: Not FDA-approved. Classified as an investigational drug. Available through research chemical suppliers and some compounding pharmacies. Not a controlled substance.
• International: Legal status varies. Sold as a "research chemical" in many countries.
• Sports: Prohibited by WADA (S2 category — Growth Hormone Secretagogues).
• SARMs classification: MK-677 is frequently marketed alongside SARMs (Selective Androgen Receptor Modulators) but is not itself a SARM. It has no androgenic activity.

Cost

MK-677 is generally the least expensive GH secretagogue option at approximately $50–150/month from research chemical suppliers. Compounding pharmacy prices are higher. Quality and purity vary significantly between sources, as the product is not regulated.

Tesamorelin (Egrifta)

What It Is

Tesamorelin is a synthetic analog of human GHRH, consisting of the full 44-amino-acid GHRH sequence with a trans-3-hexenoic acid modification at the N-terminus that improves stability and bioavailability. Unlike Sermorelin (which uses the 1-29 fragment), Tesamorelin uses the complete GHRH sequence (Spooner & Olin, 2019).

Mechanism of Action

Tesamorelin binds to GHRH receptors on pituitary somatotrophs and stimulates the synthesis and pulsatile release of endogenous GH. This increases circulating GH and IGF-1 levels. The resulting GH elevation promotes lipolysis (fat breakdown), particularly in visceral adipose tissue, which is the pathological fat depot in HIV-associated lipodystrophy (Dhillon, 2011).

Evidence

Tesamorelin has the strongest evidence base of any GH secretagogue peptide, with completed Phase 3 randomized controlled trials:

• Phase 3 trials (HIV lipodystrophy): Two pivotal Phase 3 trials demonstrated that tesamorelin (2 mg daily SC injection) reduced visceral adipose tissue (VAT) by approximately 15–18% after 26 weeks, compared to a ~5% increase in the placebo group. Trunk fat and waist circumference also decreased significantly (Falutz et al., 2007)
• Lipid profile improvements: Reductions in triglycerides and total cholesterol-to-HDL ratio were observed in treatment groups
• NAFLD/NASH (HIV patients): Tesamorelin has been studied for its effects on liver fat in HIV patients with NAFLD, showing significant reductions in hepatic fat fraction (Spooner & Olin, 2019)
• Cognitive effects: Preliminary data suggests tesamorelin may have beneficial effects on cognitive function in HIV patients, possibly through IGF-1-mediated neuroprotective effects

Side Effects (from FDA labeling)

• Injection site reactions: Most common adverse effect (erythema, pruritus, pain, irritation) — reported in up to 25% of patients
• Arthralgia (joint pain): Reported in ~13% of patients
• Peripheral edema (swelling): ~6% of patients
• Myalgia (muscle pain): ~6% of patients
• Blood glucose elevation: Tesamorelin can increase fasting glucose. Diabetic patients require monitoring
• Hypersensitivity reactions: Including rash, urticaria, and rarely anaphylaxis
• Carpal tunnel syndrome: Rare, related to GH effects on fluid retention

Dosing

Dosing should be determined by a qualified healthcare provider based on the FDA-approved prescribing information. Tesamorelin is a prescription medication with established dosing for its approved indication. For complete prescribing information, see the FDA label for Egrifta SV.

Legal Status

• United States: FDA-approved (Egrifta/Egrifta SV) for HIV-associated lipodystrophy. Prescription required. Off-label use for other indications (anti-aging, body composition) is at prescriber discretion.
• International: Approved in some countries; availability varies.
• Sports: Prohibited by WADA (S2 category).

Cost

Egrifta SV is a specialty medication with a high cost: approximately $800–1,500+ per month at retail. Insurance coverage for the approved HIV lipodystrophy indication is generally available through specialty pharmacy benefit managers, often with significant copays. Coverage for off-label use (anti-aging, body composition in non-HIV patients) is typically not covered by insurance. Compounded tesamorelin from specialty pharmacies may be available at lower cost but is not the FDA-approved formulation.

Sources

CJC-1295

Ipamorelin

Sermorelin

Tesamorelin

MK-677 (Ibutamoren)

GHRP-2 and GHRP-6

Regulatory