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Ipamorelin

low risk

Also: NNC 26-0161 · Ipamorelin acetate

Moderate Evidence Restricted

Ipamorelin is a selective GH secretagogue notable for minimal cortisol/prolactin elevation — making it the 'cleanest' GHRP. Human pharmacokinetic data exists. Most commonly combined with CJC-1295 for synergistic GH release.

Molecular Weight
711.9 Da
Formula
C38H49N9O5
Common Dosing
100–300 mcg per dose, 2–3x daily SC
Category
therapeutic
Last Reviewed
2025-01-15

Reported Benefits

Selective GH stimulation

Moderate Evidence 14 studies

Dose-dependent GH release without significant cortisol/prolactin spikes — confirmed in human and animal studies.

Body composition

Preliminary 5 studies

GH-mediated effects expected; limited direct human body composition data.

Mechanism of Action

Selective GHS-R1a agonist. Stimulates GH release with high selectivity — minimal ACTH, cortisol, or prolactin effects compared to other GHRPs.

Key Clinical Studies

Raun et al. (1998)

Controlled · Animal (dog/rat)

PubMed →

Selective GH release without cortisol/prolactin elevation

Frequently Asked Questions

Why is ipamorelin considered the 'cleanest' GHRP? ▾
Ipamorelin has high selectivity for GHS-R1a with minimal off-target receptor activation. Unlike GHRP-2 and GHRP-6, it produces negligible increases in cortisol, prolactin, and ACTH at standard doses. This makes it the preferred GH secretagogue when avoiding adrenal axis stimulation is a priority.
What is the best time to take ipamorelin? ▾
Ipamorelin is most commonly administered before bed (to coincide with natural GH pulsatility during sleep) and upon waking on an empty stomach. GH release is blunted by elevated insulin, so dosing at least 2 hours after meals is standard. Fasted injections produce the most pronounced GH pulse.
How long does ipamorelin take to work? ▾
GH pulse is detectable within 15–30 minutes of injection. IGF-1 elevation from consistent use is measurable within 2–4 weeks. Subjective benefits — improved sleep quality, recovery, body composition — are typically reported after 6–12 weeks of consistent twice-daily dosing.
Can ipamorelin cause water retention? ▾
Water retention is a potential side effect at higher doses, primarily because elevated GH increases renal sodium and water retention. At standard research doses (100–300 mcg), this effect is mild and often not noticed. It is more pronounced with CJC-1295 with DAC due to the continuous GH elevation vs. pulsatile release.
Is ipamorelin better than sermorelin? ▾
They work differently. Sermorelin is a GHRH analog (stimulates GH via the GHRH receptor). Ipamorelin is a ghrelin mimetic (stimulates GH via GHS-R1a). Neither is strictly 'better' — they can be stacked together for amplified effect. Ipamorelin has cleaner selectivity; sermorelin has longer clinical history and more published human data.

The Selectivity Advantage

Ipamorelin’s defining characteristic is selectivity. Unlike GHRP-2 and GHRP-6, it does not meaningfully elevate cortisol or prolactin. This makes it the preferred first-line secretagogue in GH optimization protocols.

Standard Stack

Ipamorelin + CJC-1295 (no DAC): different receptors (ghrelin vs. GHRH), synergistic effect, pulsatile pattern mimicking natural GH secretion.

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Regulatory Status

Restricted

Safety Profile

Side Effects

  • •Mild flushing
  • •Headache
  • •Lightheadedness
  • •Water retention (high doses)

Contraindications

  • •Active malignancy
  • •Pregnancy

Drug Interactions

  • •Somatostatin analogs
  • •Glucocorticoids

Primary Uses

GH stimulationFat lossLean muscleRecovery

Related Peptides

CJC-1295GHRP-2GHRP-6HexarelinMK-677 (Ibutamoren)

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Disclaimer: This information is for educational and research purposes only. Not medical advice. Consult a qualified healthcare provider before using any compound.