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).
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.
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):
Ipamorelin
200 mcg
20–35 ng/mL
GHRP-2
35–60 ng/mL
GHRP-6
25–45 ng/mL
Hexarelin
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.
200–300 mcg
2–3x daily
Pre-bed, morning, post-workout
150–300 mcg
Same timing
100–300 mcg
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
Hunger
Rare
Moderate
Strong (30–60 min)
Water retention
Minimal
Mild
Cortisol
No increase
Small increase
Moderate increase
Prolactin
Numbness/tingling
Occasional
Desensitization
No
The Bottom Line
Clean GH pulse, minimal sides
Maximum GH release
GHRP-2 (or Hexarelin short-term)
Appetite stimulation + GH
Beginner-friendly
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.
Related Comparisons & Guides
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.