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Growth Hormone Peptides: The Complete GH Secretagogue Guide

Ipamorelin, CJC-1295, Tesamorelin, MK-677, and Sermorelin: how they work, how to dose them, when to take them, and how they compare to each other and to exogenous GH.

18 min readUpdated March 15, 2026

Medical Disclaimer

This content is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting any hormone therapy or peptide protocol. Never self-prescribe or adjust dosages without professional guidance.

Growth hormone (GH) is one of the most important hormones for body composition, recovery, sleep quality, tissue repair, and aging. After age 20, GH output declines approximately 14% per decade. By 40, most men are producing a fraction of the GH they had in their twenties. Growth hormone peptides, or GH secretagogues, are compounds that stimulate your pituitary gland to produce more of its own GH, restoring some of that lost output without directly injecting exogenous growth hormone.

The key advantage of secretagogues over exogenous GH (Genotropin, Omnitrope, etc.) is that they work throughyour body's natural feedback system. Your pituitary still regulates the release, meaning the GH comes in physiological pulses rather than a constant flat elevation. This is generally considered healthier, more sustainable, and less likely to cause the side effects associated with supraphysiological exogenous GH (carpal tunnel, insulin resistance, organ growth).

Two Categories of GH Secretagogues

GH secretagogues fall into two categories: GHRH analogs (Growth Hormone Releasing Hormone analogs) like CJC-1295 and Sermorelin, which amplify the GH pulse when your pituitary is “ready” to release GH. And GHRPs (Growth Hormone Releasing Peptides) like Ipamorelin, which initiate a GH pulse by stimulating the ghrelin receptor. Using one from each category together (e.g., Ipamorelin + CJC-1295) produces a significantly larger and more sustained GH pulse than either alone. This is why they are almost always combined.

Ipamorelin

Ipamorelin is widely considered the cleanest GH secretagogue available. It is a pentapeptide (five amino acids) that acts as a selective growth hormone releasing peptide (GHRP) by binding to the ghrelin receptor (GHS-R1a) on the pituitary.

  • Mechanism: Selective ghrelin receptor agonist that stimulates GH release without significantly increasing cortisol, prolactin, or ACTH (unlike older GHRPs like GHRP-6 and GHRP-2)
  • Dose: 200-300mcg per injection via subcutaneous injection
  • Frequency: 1-3 times daily. Bedtime dose is most important; optional morning dose
  • Timing: Fasting state, at least 2 hours after eating, 30 minutes before sleep
  • Side effects: Mild transient head rush at injection, mild hunger in some users (less than GHRP-6), water retention (usually transient)
  • Why it's preferred: Selective GH release without cortisol or prolactin elevation makes it the safest and most sustainable GHRP for long-term use

CJC-1295 (Without DAC) / Modified GRF 1-29

CJC-1295 without DAC (also called Modified GRF 1-29 or Mod-GRF) is a synthetic analog of GHRH (growth hormone releasing hormone). It amplifies and extends the GH pulse that Ipamorelin initiates.

  • Mechanism: GHRH analog that stimulates GH release through the GHRH receptor on the pituitary. Works synergistically with GHRPs (Ipamorelin) to produce a larger, more sustained GH pulse
  • Dose: 100-200mcg per injection, typically combined with Ipamorelin in the same syringe
  • Half-life: Approximately 30 minutes (short, which preserves pulsatile release)
  • Side effects: Minimal when used at standard doses. Flushing, head rush, or mild nausea reported occasionally

Pro Tip

Many compounding pharmacies sell Ipamorelin and CJC-1295 (no DAC) pre-mixed in the same vial for convenience. This is the most practical option for most men because the two compounds are almost always used together at the same time. A typical pre-mixed vial contains 3mg Ipamorelin / 3mg CJC-1295, reconstituted with 6mL BAC water to create a simple dose of 0.3mL per injection (providing approximately 150mcg of each peptide per dose).

CJC-1295 with DAC

The DAC (Drug Affinity Complex) version of CJC-1295 is chemically modified to bind to albumin in the blood, dramatically extending its half-life to approximately 6-8 days. This creates sustained, continuous GH elevation rather than the pulsatile release seen with the non-DAC version.

  • Dose: 1-2mg per injection via subcutaneous injection
  • Frequency: Once weekly (due to the long half-life)
  • Advantages: Very convenient (once-weekly dosing), strong sustained GH elevation
  • Disadvantages: Non-pulsatile GH release is considered less physiological. May increase insulin resistance more than pulsatile options. Greater risk of GH-related side effects due to continuous elevation. Less commonly recommended by optimization practitioners

Tesamorelin

Tesamorelin is the only GH secretagogue with FDA approval. It is a synthetic GHRH analog consisting of 44 amino acids, approved for the reduction of excess abdominal fat in HIV-infected adults with lipodystrophy. We cover Tesamorelin extensively in our Physique and Metabolic Stack guide.

  • Mechanism: GHRH analog that stimulates pituitary GH release. Particularly effective at mobilizing visceral fat
  • Dose: 2mg daily via subcutaneous injection (FDA-approved dose)
  • Key evidence: Phase III trials showed 15-18% reduction in visceral fat over 26 weeks. FDA-approved with robust safety and efficacy data
  • Side effects: Injection site reactions, joint pain, peripheral edema, potential glucose metabolism effects
  • Cost: Significantly more expensive than Ipamorelin/CJC-1295 combinations
  • Best for: Targeted visceral fat reduction. Body composition optimization. Men who want the highest level of evidence behind their protocol

MK-677 (Ibutamoren)

MK-677 is unique among GH secretagogues because it is not a peptide. It is a non-peptide, orally active ghrelin receptor agonist, meaning it can be taken as a capsule or liquid rather than injected. This makes it the most convenient option but also the one with the broadest side effect profile.

  • Mechanism: Non-peptide ghrelin mimetic that stimulates GH release through the GHS-R1a receptor. Also directly stimulates appetite through ghrelin pathways
  • Dose: 10-25mg orally, once daily (typically at bedtime)
  • Half-life: Approximately 24 hours (taken once daily)
  • Advantages: Oral administration (no injections), convenient once-daily dosing, sustained GH and IGF-1 elevation
  • Disadvantages: Significant appetite increase (can be counterproductive for fat loss), water retention and bloating more pronounced than injectable secretagogues, potential insulin resistance with long-term use, lethargy and increased sleepiness

MK-677 and Insulin Sensitivity

Long-term studies of MK-677 have shown deterioration in insulin sensitivity and fasting glucose levels. If you use MK-677, monitor fasting glucose and HbA1c regularly. Men with prediabetes, metabolic syndrome, or a family history of diabetes should be particularly cautious with MK-677 and may be better served by injectable secretagogues (Ipamorelin/CJC-1295) that produce pulsatile GH release with less metabolic impact.

Sermorelin

Sermorelin is a synthetic version of the first 29 amino acids of GHRH (the natural 44-amino-acid hormone). It was one of the first GH secretagogues used clinically and was previously FDA-approved for pediatric GH deficiency testing (though this approval has been withdrawn). It remains available through compounding pharmacies.

  • Mechanism: GHRH analog similar in function to CJC-1295 (no DAC) but with a shorter half-life (approximately 10-20 minutes)
  • Dose: 200-500mcg per injection, subcutaneous, typically at bedtime
  • Advantages: Long track record of clinical use, very clean side effect profile, preserves pulsatile GH release
  • Disadvantages: Shorter half-life means a shorter and potentially smaller GH pulse compared to CJC-1295. Generally considered less potent than CJC-1295 for GH elevation. Being largely replaced by CJC-1295 (no DAC) in clinical practice

Head-to-Head Comparison

  • Best overall for optimization: Ipamorelin + CJC-1295 (no DAC). The gold standard combination with the best balance of efficacy, safety, and pulsatile physiology
  • Best for visceral fat reduction: Tesamorelin (FDA-approved, strongest evidence)
  • Most convenient (no injections): MK-677 (oral, but more side effects)
  • Cleanest side effect profile: Ipamorelin (selective GH release without cortisol/prolactin elevation)
  • Best for sleep: Any bedtime-dosed secretagogue, but Ipamorelin/CJC-1295 at bedtime consistently produces the most dramatic sleep quality improvements
  • Budget option: MK-677 (cheapest per dose, no injection supplies needed) or Sermorelin (widely available through compounding pharmacies)

Timing Is Everything

Regardless of which GH secretagogue you choose, the single most important variable for efficacy is timing. Inject on an empty stomach (at least 2 hours after eating) and do not eat for at least 30 minutes after injection. Insulin is the primary antagonist of GH release: if insulin is elevated from a recent meal, the peptide's ability to stimulate GH release is dramatically reduced. The bedtime dose is the most important because it amplifies the natural nocturnal GH pulse during deep sleep, which is when most tissue repair occurs.

The Bottom Line

GH secretagogues are among the most popular peptides in the optimization space because they address multiple goals simultaneously: improved body composition, faster recovery, better sleep, enhanced skin quality, and support for healing and repair. For most men, the Ipamorelin + CJC-1295 (no DAC) combination is the recommended starting point due to its favorable safety profile, pulsatile physiology, and well-established efficacy. Tesamorelin is the premium option for targeted visceral fat reduction with the strongest evidence base. MK-677 offers oral convenience at the cost of more side effects. And Sermorelin is a solid, safe option that is being gradually replaced by the newer alternatives.

Related Reading

Peptides Explained

The foundational guide to understanding peptides.

Longevity Stack

How GH peptides fit into a longevity protocol.

Reconstitution Guide

How to prepare GH peptides for injection.

Medical Disclaimer

This content is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting any hormone therapy or peptide protocol. Never self-prescribe or adjust dosages without professional guidance.