The Three Most Popular GHRPs
Growth Hormone Releasing Peptides (GHRPs) stimulate GH release by mimicking ghrelin at the GHSR-1a receptor. Ipamorelin, GHRP-2, and GHRP-6 are the three most studied — each with a distinct balance of potency vs side effects.
For the most potent GHRP of all, see our Hexarelin deep dive.
How GHRPs Work
All three bind the GHSR-1a receptor (ghrelin receptor) in the pituitary gland, triggering a GH pulse. The key differences are in selectivity — how much they activate other pathways beyond GH release.
More selective = fewer side effects (hunger, cortisol, prolactin) Less selective = stronger GH pulse but more off-target effects
Quick Comparison Table
Feature Ipamorelin GHRP-2 GHRP-6 GH release potency Moderate High Moderate-High Selectivity Highest Moderate Lowest Hunger stimulation Minimal Moderate Strong Cortisol increase None Mild Moderate Prolactin increase None Mild Mild-Moderate Typical dose 200–300 mcg 150–300 mcg 100–300 mcg Best for Clean GH pulse, beginners Maximum GH output Appetite stimulation + GH Side effect profile Mildest Moderate Most side effects
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Detailed Mechanism Comparison
Ipamorelin — The Selective Option
Ipamorelin is the most selective GHRP available. It triggers a clean GH pulse without significantly raising cortisol, prolactin, or appetite.
Key properties:
Does not increase cortisol — important for avoiding stress hormone elevation Does not increase prolactin — no hormonal disruption Minimal ghrelin-like hunger — suitable when appetite stimulation is unwanted Dose-dependent GH release — predictable, linear response
This selectivity makes Ipamorelin the go-to choice when a clean GH pulse is the primary goal without metabolic side effects.
GHRP-2 — The Potency Pick
GHRP-2 produces the strongest GH release among commonly used GHRPs (excluding Hexarelin, which is even more potent but desensitizes).
Key properties:
Highest sustained GH output — greater peak amplitude than Ipamorelin Mild cortisol elevation — generally considered clinically insignificant at standard doses Moderate appetite increase — noticeable but manageable No desensitization — unlike Hexarelin, GHRP-2 maintains efficacy with continued use
GHRP-2 is the choice when maximizing GH release is the priority and mild side effects are acceptable. See the full GHRP-2 Benefits Guide for a deeper look at its research-backed effects.
GHRP-6 — The Appetite Stimulator
GHRP-6 is the original GHRP and the least selective. Its strong ghrelin mimicry produces significant hunger alongside GH release.
Key properties:
Strong appetite stimulation — the most pronounced of any GHRP (can be a benefit or drawback) Moderate cortisol increase — higher than GHRP-2 Good GH release — effective but not as potent per mcg as GHRP-2 Strongest ghrelin mimicry — most activation of non-GH ghrelin pathways
GHRP-6 is studied when appetite stimulation is a desired effect (e.g., recovery from illness, muscle gain phases) alongside GH release. See the full GHRP-6 Benefits Guide for its cytoprotective and appetite-related research.
GH Release Comparison
Approximate GH pulse amplitude at standard doses (from published research):
Peptide Dose GH Peak (approximate) Ipamorelin 200 mcg 20–35 ng/mL GHRP-2 200 mcg 35–60 ng/mL GHRP-6 200 mcg 25–45 ng/mL Hexarelin 200 mcg 50–80+ ng/mL
Note: Individual response varies significantly. These are approximate ranges from research literature.
Stacking with GHRH
All GHRPs work synergistically with GHRH analogs. Combining a GHRP with a GHRH produces a much larger GH pulse than either alone:
CJC-1295 + Ipamorelin — the most popular combination, clean and predictable CJC-1295 DAC + GHRP-2 — sustained baseline elevation + strong pulses Sermorelin + Ipamorelin — natural GHRH analog + selective GHRP
For a detailed breakdown of GHRH vs GHRP mechanics, see our GHRH vs GHRP guide.
Dosing Comparison
For research and educational discussion only.
Peptide Standard Dose Frequency Timing Ipamorelin 200–300 mcg 2–3x daily Pre-bed, morning, post-workout GHRP-2 150–300 mcg 2–3x daily Same timing GHRP-6 100–300 mcg 2–3x daily 30 min before meals (hunger effect)
Timing Notes
GH release is blunted by elevated blood sugar — administer on an empty stomach or 2+ hours after eating Pre-bed dosing takes advantage of natural nocturnal GH pulse Wait 15–30 minutes after injection before eating
Side Effects Comparison
Side Effect Ipamorelin GHRP-2 GHRP-6 Hunger Rare Moderate Strong (30–60 min) Water retention Minimal Mild Mild Cortisol No increase Small increase Moderate increase Prolactin No increase Small increase Moderate increase Numbness/tingling Rare Occasional Occasional Desensitization No No No
The Bottom Line
If your research goal is... Best choice Clean GH pulse, minimal sides Ipamorelin Maximum GH release GHRP-2 (or Hexarelin short-term) Appetite stimulation + GH GHRP-6 Beginner-friendly Ipamorelin Stacking with CJC-1295 Ipamorelin (most popular combo) Long-term use Ipamorelin or GHRP-2 (no desensitization) Budget-conscious Check live pricing above
For most research contexts, Ipamorelin is the safest starting point due to its selectivity. GHRP-2 is the step up when more GH output is needed. GHRP-6 is best when appetite stimulation is a desired effect.
Hexarelin: The Strongest GHRP — Deep dive into the most potent GHRP, including desensitization and cardiac effects CJC-1295 — The GHRH analog most commonly stacked with Ipamorelin CJC-1295 DAC — Extended half-life version for sustained GH elevation Sermorelin — Natural GHRH analog, another popular GHRH stacking option Tesamorelin — FDA-approved GHRH analog for visceral fat reduction Semaglutide vs Tirzepatide — If weight management is also a research goal BPC-157 vs TB-500 — The top healing peptides, often explored alongside GH protocols
This article is for educational and research purposes only. It is not medical advice.