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Ipamorelin: Complete Guide

Ipamorelin is a selective growth hormone secretagogue that stimulates GH release by activating ghrelin receptors (GHSR-1a) in the pituitary gland. What distinguishes ipamorelin from other GH secretagogues (like GHRP-6 or GHRP-2) is its high selectivity — it stimulates GH release with minimal effects on cortisol, prolactin, and appetite. This clean side effect profile has made it one of the most popular peptides in GH optimization research.

Last updated: 2026-01-28

Quick Facts

Category
therapeutic
Also Known As
Ipamorelin
Related Goals
muscle growth, anti aging

Who Researches Ipamorelin?

Ipamorelin is researched by people who want to boost growth hormone for muscle growth, fat loss, better sleep, and anti-aging — but with the cleanest possible side effect profile. It's the most selective GH secretagogue available, meaning it doesn't spike cortisol, prolactin, or appetite the way older GHRPs do. If you're new to GH peptides, ipamorelin (usually combined with CJC-1295) is the most commonly recommended starting point. It's popular with adults over 30 noticing declining recovery, body composition changes, or sleep quality issues related to age-related GH decline.

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What Is Ipamorelin?

Ipamorelin is a pentapeptide (five amino acids: Aib-His-D-2Nal-D-Phe-Lys-NH2) that acts as a growth hormone secretagogue by binding to ghrelin receptors on pituitary somatotroph cells. It was developed by Novo Nordisk in the 1990s and progressed through Phase 2 clinical trials for post-operative ileus (gut motility after surgery) before development was discontinued for business reasons.

Ipamorelin's selectivity is its defining characteristic. Unlike GHRP-6 (which stimulates intense hunger and raises cortisol) or GHRP-2 (which also increases prolactin), ipamorelin produces a clean GH pulse with minimal off-target hormonal effects. This selectivity comes from its specific receptor binding profile — it activates GHSR-1a efficiently without strong activation of the pathways responsible for cortisol release and appetite stimulation.

Mechanism of Action

Ipamorelin works via a different pathway than GHRH analogs like sermorelin or CJC-1295:

  • GHRH analogs (sermorelin, CJC-1295): Bind GHRH receptors → stimulate GH synthesis and release
  • Ipamorelin: Binds ghrelin receptors (GHSR-1a) → amplifies GH release pulses

These two pathways are complementary, which is why ipamorelin is frequently combined with CJC-1295 or sermorelin — the GHRH analog initiates the GH pulse while ipamorelin amplifies it, producing greater total GH release than either alone.

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Dosage Overview

ProtocolDoseFrequencyTiming
Standalone200–300 mcg2–3× dailyMorning, post-workout, bedtime
With CJC-1295 (no DAC)200 mcg each2–3× dailySame injection
With sermorelin200 mcg ipamorelin + 200 mcg sermorelinBefore bedtimeFasted

Fasted administration is important — food intake (especially carbohydrates) blunts GH release. Use the peptide calculator for reconstitution.

Side Effects & Safety

  • Injection site reactions: Mild redness — most common
  • Head rush/flushing: Transient, particularly with initial doses
  • No significant cortisol increase — unlike GHRP-6 and GHRP-2
  • No significant appetite stimulation — unlike GHRP-6
  • No significant prolactin increase — unlike GHRP-2
  • Mild water retention: Related to GH elevation, less pronounced than with exogenous GH

Frequently Asked Questions

References

  1. Raun K, et al.. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 1998.
  2. Johansen PB, et al.. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Hormone & IGF Research, 1999.

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Peptides Insider Editorial Team

Our content is reviewed for accuracy and grounded in peer-reviewed research where available. We do not provide medical advice. Always consult a qualified healthcare professional.