Growth Hormone Peptides: Complete Guide to GH Secr…

Growth hormone secretagogues are peptides that stimulate the pituitary gland to produce and release more growth hormone. Unlike injectable HGH, they work through the body's own feedback systems, producing pulses of GH that more closely resemble natural physiology. This guide covers every major GH peptide, how they differ, and how to apply them.

The Two Axes of GH Stimulation

GH secretagogues work through two distinct receptor pathways that are complementary rather than redundant. Understanding this is fundamental to building effective protocols.

GHRH analogs (CJC-1295, Sermorelin, Tesamorelin) act on the GHRH receptor in the anterior pituitary, which amplifies the amplitude of GH pulses—making each pulse larger without increasing pulse frequency. They work best when combined with a ghrelin-axis peptide.

Ghrelin mimetics / GHRPs (Ipamorelin, GHRP-2, GHRP-6, Hexarelin) act on the ghrelin receptor (GHSR-1a), increasing both GH pulse amplitude and stimulating an additional pulse. They also reduce somatostatin, the hormone that inhibits GH release, effectively opening the window wider for GH secretion.

Combining one from each class produces 2-3x the GH output of either alone—this is the biological basis for the CJC-1295 + Ipamorelin stack.

CJC-1295: The Gold Standard GHRH Analog

CJC-1295 exists in two forms with very different pharmacokinetics. CJC-1295 without DAC (Modified GRF 1-29) has a half-life of 15-30 minutes, producing a single defined GH pulse when injected—ideal for mimicking natural pulsatile GH release. CJC-1295 with DAC incorporates a drug affinity complex that binds to albumin, extending the half-life to 6-8 days and producing sustained GH elevation.

Without DAC: 100-300 mcg per injection, 2-3x daily (pre-workout and bedtime are common) or once at bedtime. With DAC: 1-2 mg subcutaneously once or twice per week.

Ipamorelin: The Cleanest GHRP

Ipamorelin is a selective ghrelin mimetic with a significant advantage over older GHRPs: it does not elevate cortisol, prolactin, or ACTH at standard doses. This makes it the preferred GHRP for long-term use in health-focused protocols. It produces strong GH pulses at 100-300 mcg per injection and has minimal desensitization with appropriate cycling.

GHRP-2 and GHRP-6: More Power, More Side Effects

GHRP-2 and GHRP-6 are older hexapeptide GHRPs with stronger GH output than Ipamorelin but with significant differences. GHRP-6 causes pronounced appetite stimulation—it is often used intentionally during bulk phases for this reason. Both elevate cortisol and prolactin, which limits their use in prolonged protocols. GHRP-2 is cleaner than GHRP-6 on appetite but still raises cortisol. Dose: 100-200 mcg per injection.

Sermorelin: The Conservative Starting Point

Sermorelin is a 29-amino-acid GHRH fragment and the first GH secretagogue approved for clinical use (in children with GH deficiency). It has the most favorable safety profile of any GH peptide and is widely prescribed by anti-aging clinics for adults with age-related GH decline. Its relatively short half-life means effects are mild but reliable. Dose: 200-500 mcg at bedtime subcutaneously.

Tesamorelin: FDA-Approved for Fat Reduction

Tesamorelin is an FDA-approved GHRH analog (brand name Egrifta) indicated for visceral fat reduction in HIV-associated lipodystrophy. In broader anti-aging and body composition use, it produces significant reductions in visceral adipose tissue at 1-2 mg/day. It also improves cognitive function in trials of older adults—GH has direct effects on hippocampal neurogenesis.

Hexarelin: Potency with Cardiac Benefits

Hexarelin is the most potent GHRP available, producing the largest GH spikes of any peptide in this class. It also has direct cardiac receptor activity independent of its GH effects, making it uniquely interesting for cardiac aging research. Its potency also means faster receptor desensitization—protocols should cycle 4-6 weeks on, 2-3 weeks off.

Optimal Timing and Administration

GH secretagogues are best taken on an empty stomach—glucose and fatty acids blunt GH release. The two optimal windows are: (1) pre-sleep, when GH naturally peaks, allowing peptides to amplify the natural pulse; and (2) immediately post-workout, when GH is already elevated and peptides can further extend the anabolic window.

Subcutaneous injection into abdominal fat delivers consistent absorption. Rotate injection sites to prevent lipohypertrophy.

FAQ

Do GH secretagogues suppress natural GH production? Unlike exogenous HGH, secretagogues work through the body's own feedback axis. When stopped, pituitary GH production returns to baseline quickly—typically within days. There is no evidence of lasting suppression with responsible cycling.

What IGF-1 level should I target when using GH peptides? Most anti-aging physicians aim to optimize IGF-1 to the upper quartile of the age-matched reference range—typically 200-350 ng/mL for men aged 35-55. Supraphysiological IGF-1 above 400 ng/mL chronically raises theoretical cancer risk and is generally avoided.

Can GH peptides be used with TRT? Yes. Testosterone and GH operate through complementary anabolic axes. Many men on TRT add GH secretagogues to address body composition and recovery aspects that testosterone does not fully normalize.

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Growth Hormone Peptides: Complete Guide to GH Secretagogues