The cleanest growth hormone secretagogue — selective GH release without cortisol or prolactin spikes.
Ipamorelin is a pentapeptide growth hormone secretagogue — specifically, a ghrelin receptor agonist (GHS-R1a agonist). It stimulates GH release from the pituitary gland in a manner similar to ghrelin, the 'hunger hormone,' but with much greater selectivity. The key distinction: ipamorelin releases GH without significantly raising cortisol, ACTH, or prolactin levels.
This selectivity makes ipamorelin particularly attractive clinically. Older GHRPs (like GHRP-2 and GHRP-6) can meaningfully increase cortisol and prolactin — stress-related and potentially problematic hormones. Ipamorelin's clean profile allows GH stimulation without these side effects, making it the preferred GHRP for most clinical protocols.
Ipamorelin is almost universally combined with a GHRH analog (CJC-1295 or sermorelin) in clinical practice. The combination takes advantage of complementary mechanisms: GHRH increases the number of GH-secreting cells (somatotrophs) and the amount of GH they secrete, while ipamorelin directly triggers GH release. The result is synergistic, pulsatile GH stimulation that closely mimics natural physiology.
Ipamorelin was originally developed by Novo Nordisk and studied in clinical trials. Research demonstrated dose-dependent GH release with minimal effects on other pituitary hormones. GH pulses produced were more physiological (shorter duration) than those from GHRH analogs alone, reducing risk of desensitization.
Animal studies show bone density benefits, lean mass increases, and improved GI motility. Human data comes largely from clinical observations rather than large trials, but extensive safe use has been documented in compounding medicine contexts.
📚 Key Reference: PMID: 9849822 (Ipamorelin selectivity study)
Very well-tolerated. Most common side effects: injection site reactions, mild headache, and transient facial flushing. No significant cortisol or prolactin elevation distinguishes it from older GHRPs. As with all GH secretagogues, excessive use can cause GH-related side effects (joint pain, water retention, glucose effects). Monitor IGF-1. Contraindicated with active malignancy. Consult your provider.
Not FDA-approved. Available through compounding pharmacies. Research-grade classification. WADA prohibited. Legal for prescription compounding under medical supervision in the US.