Ipamorelin is the most selective growth hormone secretagogue (GHS) available, a synthetic pentapeptide (MW ~711.86 g/mol, formula C38H49N9O5) that stimulates pulsatile GH release from the pituitary gland without significantly affecting cortisol, prolactin, or appetite. It is widely regarded as the mildest GHS, making it popular in anti-aging, body composition, and recovery contexts. However, research on ipamorelin is limited, and it is not FDA-approved for any indication.
Category: Growth Hormone Secretagogue. Evidence rating: D (animal/preclinical only).
Clinical status: Research-only / Not approved for human use
Ipamorelin (sequence: Aib-His-D-2Nal-D-Phe-Lys-NH2) selectively binds to the Growth Hormone Secretagogue Receptor (GHS-R1a) on anterior pituitary somatotroph cells, increasing cAMP and activating protein kinase A to promote pulsatile GH secretion. Its structural specificity means it fits only the…
Research base: 1 registered clinical trial and 6 indexed publications reference Ipamorelin.
Safety considerations: Widely regarded as the mildest GHS available; minimal side effects in published animal and human studies; Common: injection site reactions (redness, swelling, bruising) in 15-30% of users, resolving within 24-48 hours; Common: mild temporary "head rush" or flushing immediately after injection due to sudden vasodilation.
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-08-12.
Related peptides: CJC-1295, Sermorelin, Tesamorelin.
Compare: Ipamorelin vs CJC-1295, Ipamorelin vs Sermorelin, Ipamorelin vs Tesamorelin.
Ipamorelin is the most selective GHS available. Its pentapeptide structure fits only the GH-releasing pocket of the ghrelin receptor, stimulating GH release without significantly increasing cortisol, prolactin, or appetite. GHRP-6 and GHRP-2 hit the receptor more broadly, causing hunger, cortisol spikes, and prolactin elevation.
Ipamorelin is available as a research chemical but is not FDA-approved for human consumption. It is banned by WADA as an S2 growth factor, prohibited at all times in competitive sports.
The ghrelin receptor has different binding pockets. Ipamorelin fits only the GH-releasing pocket due to its precise molecular shape, not the appetite or ACTH/cortisol pockets. However, as a ghrelin mimetic, some users may experience mild appetite increase, which can be managed by adjusting dosing protocols.
Research subjects commonly receive 200-300 mcg per day (split into 2-3 SC doses) for 8-12 weeks, followed by a 4-week washout. Injections must be on an empty stomach (1.5+ hours after eating) to avoid blunting GH release. Common three-dose protocol: morning (fasted), post-workout, and 2 hours before bedtime.
Stacking ipamorelin with CJC-1295 No DAC is commonly discussed as they target complementary mechanisms (GHRH + GHS pathways), creating amplified GH pulses. This has not been studied in controlled human trials.