GHRP-2

GHRP-2 (growth hormone-releasing peptide-2), also called pralmorelin or KP-102, is a synthetic hexapeptide that binds the ghrelin receptor (GHS-R1a) on pituitary somatotrophs and hypothalamic neurons to stimulate release of endogenous growth hormone. It was among the first GHRPs developed, originating from the foundational research of Cyril Bowers at Tulane in the late 1980s. GHRP-2 is approved in Japan as a diagnostic agent (pralmorelin) for pediatric growth hormone deficiency testing, but is not FDA-approved in the US. Research-grade use for performance and body composition is off-label. It synergizes strongly with GHRH analogs (sermorelin, CJC-1295) to produce 3-5x amplified GH pulses vs either alone.

Both are GHS-R1a agonists, but they differ in selectivity. GHRP-2 produces a larger absolute GH pulse amplitude but has meaningful cross-reactivity with prolactin and cortisol pathways, elevating both modestly (cortisol +15-25% above baseline). Ipamorelin is more selective for the GH axis and produces minimal prolactin or cortisol changes. GHRP-2 also has stronger appetite-stimulating effects. The tradeoff: GHRP-2 for maximum GH pulse in short-duration aggressive phases; ipamorelin for clean long-term daily use. Users with baseline anxiety, HPA axis concerns, or prolactin issues generally do better on ipamorelin. Users who want appetite stimulation during a bulking phase may prefer GHRP-2.

Standard subcutaneous protocol is 100-200 mcg per injection, 2-3 times daily. Beginners start at 100 mcg twice daily (pre-breakfast and pre-bed) and titrate up. Intermediate users typically dose 150-200 mcg three times daily (pre-breakfast, pre-training, pre-bed). The single-injection ceiling is around 300 mcg — above that, GHS-R1a receptor saturation prevents additional GH release. Always dose in a fasted state (2-3 hours after last meal), as elevated blood glucose and insulin blunt GH release through increased somatostatin tone. Consistency of timing matters — the GH axis entrains to regular schedules.

GHRP-2 can cause modest weight gain through two mechanisms. First, the ghrelin-receptor agonism directly increases appetite — users typically notice measurable hunger within 30-60 minutes of injection. If this increased appetite is met with caloric surplus, weight gain follows. Second, GH-axis stimulation mildly promotes fluid retention, especially in the first 2-3 weeks of daily use. In users on a deficit or maintenance intake, body composition typically shifts toward slightly more lean mass and slightly less fat, with modest or no scale weight change. For users trying to lose weight, ipamorelin is usually a better choice because of its less pronounced appetite effect.

Yes — this is the classical and most pharmacologically significant stack in the GH-secretagogue space. GHRP-2 activates the ghrelin/GHS-R1a pathway; CJC-1295 (either no-DAC or DAC variant) activates the GHRH/GHRHR pathway. The two mechanisms converge intracellularly through complementary G-protein signaling, amplifying GH pulse amplitude 3-5x above either compound alone (Bowers 1991). Standard stack: GHRP-2 100-200 mcg + CJC-1295 no-DAC 100-200 mcg, drawn into the same insulin syringe, injected simultaneously SC 2-3 times daily fasted. With CJC-1295 DAC, the GHRP-2 becomes 'pulse-on-top-of-continuous-tonic' GHRH — less clean pharmacologically but more convenient (once or twice weekly CJC-DAC vs. daily sermorelin/no-DAC).

The most common effects are increased appetite (from ghrelin-receptor agonism), mild transient cortisol elevation (+15-25% above baseline for 60-90 minutes), modest prolactin elevation (usually trivial), flushing immediately post-injection, and injection site reactions. Less common effects include mild fluid retention in the first weeks, vivid dreams with bedtime dosing, transient insulin sensitivity reduction with chronic use, headache, and occasional nausea. Rare effects include hypotension (mainly with IV administration), hypersensitivity, and paresthesia. Long-term concerns include modest insulin resistance and GHS-R1a receptor desensitization with chronic daily dosing — cycling protocols help prevent both. Theoretical cancer concern from sustained IGF-1 elevation applies to all GH-axis interventions.

GHRP-2 (pralmorelin) is approved in Japan as a diagnostic agent for pediatric growth hormone deficiency testing. It is not FDA-approved in the United States for any indication. In the US research-peptide market, GHRP-2 is sold under research-only classification through peptide suppliers. Users should understand this legal context, source from vendors with third-party purity testing, and ideally work with a medical practitioner familiar with off-label peptide use. Some 503B compounding pharmacies include GHRP-2 in their peptide offerings for physician-supervised off-label use. See our best vendors guide for 2026 for reliable sources and peptide-friendly clinical practices.

A single GHRP-2 injection produces measurable GH elevation within minutes, with peak serum GH at roughly 15-30 minutes post-injection and return to baseline by 90-120 minutes. However, the clinically meaningful body composition and performance effects take 8-16 weeks of consistent dosing to manifest. IGF-1 stabilizes at its new elevated setpoint around weeks 4-6. Sleep quality improvements (vivid dreams, enhanced slow-wave sleep) often appear within the first 2 weeks. Lean body mass changes become detectable at weeks 8-12. Recovery and training-tolerance improvements are often noticed subjectively within 2-3 weeks but are harder to measure objectively.

Cycling is recommended for long-term use because chronic GHS-R1a receptor stimulation can produce modest tachyphylaxis (receptor desensitization) over months. Common cycling approaches: (1) 5 days on / 2 days off weekly — weekend pauses maintain responsiveness; (2) 8 weeks on / 2 weeks off — macro-cycle for full GHS-R1a reset; (3) Continuous daily with quarterly IGF-1 monitoring and dose adjustment if plateau detected. Unlike anabolic steroid cycling, peptide cycling is not primarily about protecting endogenous hormone production — the GH pituitary reserve recovers quickly — but about maintaining receptor sensitivity. Users who stack with CJC-1295 DAC (8-day half-life) will naturally have continuous GHRH exposure and benefit more from periodic GHS-R1a cycling.

They target the same receptor (GHS-R1a) but have fundamentally different pharmacology. GHRP-2 produces short pulses (15-30 min half-life) multiple times daily via SC injection; MK-677 produces 24-hour continuous receptor occupancy via once-daily oral dosing. GHRP-2 is cheaper per-dose, has cleaner pulsatile pharmacology that more closely mimics natural GH release patterns, and can be titrated precisely. MK-677 is dramatically more convenient (oral, once daily, no needles) but produces more significant fluid retention, more pronounced appetite stimulation, and more measurable insulin resistance over time. Users prioritizing convenience pick MK-677; users prioritizing clean pulsatile pharmacology and minimum long-term metabolic disruption pick GHRP-2 (or ipamorelin for even cleaner profile). See MK-677 for full comparison.