Ipamorelin Guide
The Most Selective GHRP: Science, Protocol & the CJC-1295 Stack
Ipamorelin is a pentapeptide GHSR-1a agonist and the most selective growth hormone releasing peptide ever developed. Unlike every other GHRP, it triggers a clean GH pulse with zero elevation of cortisol, prolactin, or ACTH — making it the foundation of most modern peptide GH protocols.
What Is Ipamorelin?
Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH2) is a synthetic pentapeptide — five amino acids — engineered to be a highly selective agonist of the growth hormone secretagogue receptor 1a (GHSR-1a), the same receptor targeted by ghrelin. It was originally developed by Novo Nordisk in the 1990s and remains the reference compound for GHRP selectivity research.
The critical distinction that sets ipamorelin apart from all other GHRPs is its extraordinary receptor selectivity. While GHRP-6 and GHRP-2 also activate GHSR-1a, they also bind adjacent receptors that drive cortisol and prolactin release, and trigger significant ghrelin-like appetite stimulation. Ipamorelin does none of this at standard doses — it releases GH and essentially nothing else. This is not a marketing claim but a verified pharmacological property established in multiple studies.
Mechanistically, ipamorelin acts as a GHSR-1a agonist and synergizes with endogenous GHRH (Growth Hormone Releasing Hormone) produced by the hypothalamus. When administered alongside a GHRH analogue such as CJC-1295, the two mechanisms combine to produce a supraphysiologic but still pulsatile GH response — 3 to 4 times the GH release of either compound used alone.
Pentapeptide structure engineered for maximum GHSR-1a selectivity with minimal off-target receptor binding.
Short injection-based half-life produces a physiologic pulsatile GH burst rather than a sustained flat elevation.
No elevation of cortisol, prolactin, or ACTH at standard doses — the defining pharmacological property of ipamorelin.
How Ipamorelin Works
GHSR-1a Agonism
Ipamorelin binds the growth hormone secretagogue receptor 1a on pituitary somatotrophs — the same receptor that ghrelin activates. This binding triggers a calcium-dependent signaling cascade that stimulates GH synthesis and pulsatile release from the pituitary gland. The key difference from ghrelin is that ipamorelin does not activate the parallel receptor pathways that drive hunger, cortisol, and prolactin release.
Synergy with Endogenous GHRH
Ipamorelin's GH release is dramatically amplified when endogenous GHRH signaling is present or when an exogenous GHRH analogue (like CJC-1295) is co-administered. The GHSR-1a and GHRH receptor pathways are genuinely synergistic at the pituitary — both are needed simultaneously to produce a maximal GH pulse. This is the mechanistic basis for the CJC-1295 + ipamorelin stack being so much more effective than either alone.
IGF-1 Downstream Response
Elevated GH from repeated ipamorelin pulses signals the liver to produce Insulin-like Growth Factor 1 (IGF-1), which mediates most of GH's anabolic and body composition effects. Regular ipamorelin use (2–3x daily) raises IGF-1 approximately 15–30% from baseline. When stacked with CJC-1295 DAC, the IGF-1 rise can exceed 50% — important context for monitoring and staying within physiologic reference ranges.
No Desensitization
Unlike some peptides and GH secretagogues, ipamorelin shows no evidence of receptor desensitization at standard doses with ongoing use. This is mechanistically explained by its pulsatile delivery pattern — the receptor is not chronically occupied. Continuous GHSR-1a stimulation (as with some small molecule secretagogues) produces tachyphylaxis; pulsatile agonism as produced by ipamorelin injections does not.
Dosage & Protocol
Ipamorelin is administered subcutaneously (SQ) — typically abdomen, thigh, or love handles — using an insulin syringe. Timing relative to meals and sleep matters significantly because GH release is blunted in the presence of elevated blood sugar (insulin suppresses GHRH). Injections should be taken on an empty stomach or at least 90 minutes after a meal.
Pre-Sleep Protocol (Most Common)
Leverages the body's largest natural GH pulse that occurs in early deep sleep. Injected 30–60 min before bed, ipamorelin amplifies this pulse dramatically. This single pre-sleep dose is the most efficient injection for GH and sleep quality benefits.
- • Dose: 300mcg SQ
- • Timing: 30–60 min before sleep
- • Fast 90 min before injection
- • 1x/day minimum effective protocol
2x Daily Protocol
The most popular protocol for body composition and anti-aging — balances IGF-1 elevation with manageable injection burden. Morning injection is taken fasted; pre-sleep injection remains essential. Roughly doubles the cumulative GH exposure vs 1x/day.
- • Morning: 300mcg SQ fasted
- • Pre-sleep: 300mcg SQ
- • Wait 60 min after morning injection before eating
- • Cycle: 12–16 weeks on, 4 weeks off
3x Daily Protocol (Advanced)
Adds a pre-workout or mid-afternoon injection for maximum GH pulsatility throughout the day. Used by advanced users targeting significant body recomposition. Higher daily dose means more frequent IGF-1 monitoring is warranted.
- • Dose: 200–300mcg per injection
- • Morning, pre-workout, pre-sleep
- • Monitor IGF-1 at 8 and 16 weeks
- • Consider IGF-1 reference range cap
The Gold-Standard Stack: CJC-1295 + Ipamorelin
The combination of CJC-1295 (No DAC) + ipamorelin is widely regarded as the gold-standard peptide GH stack, and the mechanistic rationale is clear. CJC-1295 is a GHRH analogue — it activates the GHRH receptor on pituitary somatotrophs and primes the gland to respond. Ipamorelin then activates the GHSR-1a receptor simultaneously. Because these two receptors activate complementary intracellular pathways (cAMP via GHRH-R, and calcium via GHSR-1a), their co-stimulation produces 3–4x the GH pulse of either alone.
Critically, this synergistic GH pulse remains pulsatile — it is not a continuous flat elevation. The pituitary releases a burst of GH that clears within 1–3 hours, mimicking (but amplifying) the natural physiologic GH pulsatility that the body relies on for anabolic signaling, fat metabolism, and sleep architecture. This is a meaningful advantage over continuous GH administration or long-acting secretagogues that flatten GH into a tonic elevation.
Standard Stack Protocol
- CJC-1295 No DAC: 100–200mcg per injection
- Ipamorelin: 200–300mcg per injection
- Timing: Mix in same syringe or inject back-to-back
- When: Pre-sleep (mandatory) + morning fasted (optional)
- Cycle: 12–16 weeks; monitor IGF-1 at 12 weeks
Expected Benefits of the Stack
- IGF-1 rise: 30–50% from baseline (vs 15–30% with ipamorelin alone)
- Body composition: Accelerated fat loss, lean mass preservation or gain
- Sleep quality: Deeper slow-wave sleep, improved recovery within 2–4 weeks
- Recovery: Faster repair from training; some users report joint and tendon improvements
- Skin/hair: Reported improvements in skin texture and hair quality with longer cycles
Frequently Asked Questions
What makes ipamorelin the most selective GHRP?
Ipamorelin (Aib-His-D-2-Nal-D-Phe-Lys-NH2) is a pentapeptide GHSR-1a agonist that selectively stimulates GH release without elevating cortisol, prolactin, ACTH, or causing ghrelin-mediated hunger. This selectivity is its defining property — every other GHRP in common use produces at least some off-target hormonal elevation at standard doses. The unique amino acid composition, particularly the D-2-Nal and Aib modifications, determines this receptor selectivity profile.
What is the best ipamorelin dosage and timing protocol?
The most widely used protocol is 200–300mcg subcutaneously injected 30–60 minutes before sleep, which leverages and amplifies the body's largest natural GH pulse. A second morning injection of 200–300mcg is common in 2x/day protocols. When stacked with CJC-1295 No DAC (100–200mcg), inject both simultaneously at each dose window. All injections should be taken with blood sugar stable — at least 90 minutes after a meal.
How much does ipamorelin raise IGF-1?
Used alone with regular 2–3x daily dosing, ipamorelin typically raises IGF-1 15–30% from baseline over 8–12 weeks. When stacked with CJC-1295 DAC (which maintains a continuous GHRH signal), IGF-1 elevation can exceed 50% from baseline. Monitoring IGF-1 at baseline and at 12 weeks is strongly recommended to ensure levels remain within the upper physiologic reference range rather than crossing into supraphysiologic territory.
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