Growth hormone (GH) is one of the most important anabolic hormones in the human body, governing muscle growth, fat metabolism, tissue repair, sleep quality, and longevity-related cellular functions. After age 30, GH secretion declines at approximately 14 percent per decade, contributing to the progressive changes in body composition, recovery capacity, and energy that most people attribute simply to "getting older."
Growth hormone peptides - or GH secretagogues - stimulate your own pituitary gland to produce and release more GH in a physiological, pulsatile pattern. They are fundamentally different from injecting exogenous HGH, and for most patients represent the safer, more accessible, and more clinically appropriate approach to GH optimisation.
The GH Peptide Landscape
Sermorelin
Sermorelin is a synthetic analogue of the first 29 amino acids of GHRH (growth hormone-releasing hormone). It acts directly on pituitary GHRH receptors to stimulate GH release.
Key characteristics:
- Produces physiological, pulsatile GH release
- Short half-life (requires daily injection for consistent effect)
- Well-established safety profile with the most clinical history
- Natural feedback mechanisms remain intact
Sermorelin is the foundational GH peptide and was the first to see widespread clinical use.
Ipamorelin
Ipamorelin acts on ghrelin receptors (GHSR) in the pituitary and hypothalamus. It is highly selective for GH secretion without significantly affecting cortisol, prolactin, or other hormones.
Key characteristics:
- Produces clean, selective GH pulses
- Minimal effects on cortisol or prolactin (unlike earlier GHRPs)
- Short half-life, typically injected before sleep for optimal GH pulsatility
- Excellent tolerability profile
CJC-1295
CJC-1295 is a modified GHRH analogue. The DAC (drug affinity complex) version has an extended half-life of 6 to 8 days, providing sustained tonic GH stimulation rather than a single pulse.
Key characteristics:
- Extended half-life allows less frequent injection (weekly or twice weekly)
- Raises basal GH secretion over time
- Works synergistically with ipamorelin (different receptor, complementary mechanism)
- IGF-1 elevations are more sustained than shorter-acting peptides
GHRP-6 and GHRP-2
The original ghrelin receptor agonists (see separate article for full details). Effective GH stimulators but with notable side effects: significant cortisol and prolactin elevation, and strong ghrelin-mediated appetite stimulation. Less preferred than ipamorelin for most clinical purposes due to these off-target effects.
Hexarelin
One of the most potent GHRP family peptides, producing the strongest GH pulse per dose. Higher cortisol elevation than ipamorelin; rapid tachyphylaxis (loss of response) with continuous use limits long-term use. Better suited to short cycles.
MK-677 (Ibutamoren)
An oral ghrelin receptor agonist that produces sustained GH and IGF-1 elevation with oral administration once daily. Significant appetite stimulation and water retention are notable effects. Not a peptide (small molecule), but functionally a GH secretagogue.
How GH Peptides Work vs Direct HGH
| Factor | GH Peptides | Direct HGH Injection | |---|---|---| | Mechanism | Stimulate pituitary's own production | Exogenous replacement | | Pulsatility | Maintained | Non-physiological | | Feedback regulation | Preserved | Bypassed | | Cost | Accessible | Very expensive | | Side effect profile | Mild, transient | Higher at equivalent GH levels | | Pituitary atrophy risk | None | Possible with prolonged use |
For the vast majority of patients who are not confirmed GH-deficient by formal provocative testing, GH secretagogue peptides are the appropriate clinical approach.
Choosing the Right Protocol
The right GH peptide depends on your primary goals:
- Body recomposition + testosterone support: CJC-1295 + Ipamorelin stack (Longegra signature)
- Recovery and injury healing: BPC-157 + ipamorelin/CJC-1295
- Anti-aging + longevity: Sermorelin or CJC-1295 + ipamorelin long-term protocol
- Sleep quality improvement: Ipamorelin (night dosing) as the primary intervention
- Maximum short-term GH elevation: Hexarelin (short cycles only, physician-supervised)
Frequently Asked Questions (FAQs)
IGF-1 is the primary blood marker of GH status. An IGF-1 below the age-appropriate normal range suggests GH deficiency. Longegra tests IGF-1 as part of our intake panel.
